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Endangered and Threatened Species of the Platte River (2005)

Chapter: 3 Law, Science, and Management Decisions

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Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
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3
LAW, SCIENCE, AND MANAGEMENT DECISIONS

The issues related to threatened and endangered species in the Platte River Basin are products of complicated interactions between legal frameworks and applied science. This chapter reviews the Endangered Species Act (ESA) from a legal and policy perspective, examines the practice and application of science in implementing the ESA, and concludes by placing the Platte River conflict in a broader national context.

The evolution and codification of national wildlife policy in the United States provide the context for the present issues concerning the four threatened or endangered species in the Platte River Basin. Wildlife has played an important role in America’s cultural self-image. North American Indians often have regarded wildlife as sacred, and many tribes were divided into clans named for wildlife species. When European settlers founded the United States, symbols of national vitality began with the bald eagle and continued with bison and other wildlife representing the character of the nation. Fish and wildlife have continued to play important roles as cultural images, ranging from symbols of political jurisdictions, such as tribes and states, to nicknames for schools and sports teams. Thomas Jefferson’s first description of the nation’s physical geography began with a discussion of rivers and fishes (Jefferson 1787), and John James Audubon’s works brought American birdlife to the attention of the world. Concern about the extinction of species during the nineteenth century attracted considerable attention, and at the dawn of the twentieth century Congress adopted the Lacey Act of 1900 as the first national wildlife-protection statute. The sponsor of

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
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the act, John F. Lacey, expressed the issue clearly: “[in] many of the states the native birds have been well-nigh exterminated” (Lacey 1900). In a related development, President Theodore Roosevelt established the nation’s first wildlife refuge in 1903 at Pelican Island, Florida.

During the twentieth century, interest in protecting native wildlife species grew. Determined to avoid the loss of more species, as occurred with the passenger pigeon and the Carolina parakeet, and spurred by drastically declining numbers of popular, visible species—such as the brown pelican, wading birds, and some species of game ducks—state and federal policy-makers established refuges and management programs. Since 1966, efforts at the federal level have included three statutes that provide the basic framework for the nation’s policy regarding endangered wildlife species.

The present federal legislative authority for dealing with endangered species is the product of a progression of three major acts of Congress. The first, the Endangered Species Preservation Act of 1966, was the formal beginning of federal efforts. It was ineffective because of several minor flaws and three major shortcomings: it did not prohibit the taking of endangered species, it did not recognize all types of endangered species, and it did not provide habitat protection (Bean and Rowland 1997). The Endangered Species Conservation Act of 1969 clarified congressional intent in some ways, but it did not rectify many of the problems in the earlier act. President Richard Nixon expressed widely held concerns that existing law “simply does not provide the kind of management tools needed to act early enough to save a vanishing species” (Nixon 1972).

LEGAL AND INSTITUTIONAL BACKGROUND

Endangered Species Act

Management of lands and water in the Platte River Basin is subject to a complex web of local, state, and federal law. The federal ESA, however, is a major regulatory force that limits land and water use in the basin. Federal decisions under the ESA triggered the present committee’s review and have been a primary motivating force behind development of the Platte River Cooperative Agreement.

The Endangered Species Act of 1973 remedied the shortcomings of the earlier legislative attempts, and it is the defining instrument of present policy regarding imperiled wildlife (16 U.S.C.A. § 1531-1544). Congress found that the ESA was necessary to protect the “esthetic, ecological, educational, historical, recreational, and scientific value” provided by fish, wildlife, and plants. The major purposes of the act are to provide for the conservation of endangered species and the ecosystems on which they depend. The act defines conservation as the use of all methods necessary for the recovery of species to

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
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the point where they can be removed from the protected list. Species are protected under the act if they are listed as “endangered” or “threatened.” An endangered species is one that is in danger of extinction throughout all or a substantial part of its range, and a threatened species is one that is likely to become endangered in the foreseeable future.

The ESA is focused on individual listed entities. It therefore does not protect ecosystems themselves, but only to the extent that they are needed by listed species. The ESA may be compatible with, but it does not require, the broader protection of ecosystems or biodiversity.

Designation of Critical Habitat

The focus of this committee’s review is the habitat needs of the Platte River endangered and threatened species. The ESA protects critical habitat, defined as the specific areas that contain physical or biological features essential to the conservation of the species and that may require special management considerations or protection (ESA § 3(5)). This report uses the term only to refer to areas that have been formally designated under the ESA.

The congressional authors of the ESA envisioned that the designation of critical habitat by the U.S. Fish and Wildlife Service (USFWS) would take place at the same time that a species was listed, but this provision of the act has not generally been carried out. USFWS believes that designation of statutory critical habitat provides little additional protection for listed species and instead has relied on other methods—including agreements with federal agencies, states, tribes, and private persons or organizations—to promote conservation of endangered species. The designation of critical habitat has often been accompanied by long legal challenges, so throughout the nation most current critical habitat designations are either by court order or by court-supervised settlements (McCue 2003). The critical habitat provisions of the ESA have long been perplexing and controversial. As enacted (in 1973), the ESA contained a regulatory provision that limited modification of critical habitat by federal actions, but it did not define the term “critical habitat” or provide a process for its designation (Patlis 2001). USFWS and the National Marine Fisheries Service jointly published their initial interpretation of the term critical habitat in 1975 (Fed. Regist. 40:17764 [1975]). Using that interpretation, USFWS issued its first proposed determinations of critical habitat, covering six species, including the whooping crane, later in that year (Fed. Regist. 40:58308 [1975]). In 1978, Congress added a statutory definition of and process for designating critical habitat (Patlis 2001).

Areas outside the present range of a species may be included in critical habitat but only if designation limited to the present range would be

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
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inadequate to ensure its conservation (50 CFR 424.12(e)). Because conservation is defined to mean progress toward recovery and delisting, critical habitat must include sufficient habitat to support a recovered population, which may be larger than the population at the time of listing or larger than a minimal viable population.

In determining critical habitat, USFWS (50 CFR § 424.12(b)) considers the species need for

  • Space for individual and population growth and for normal behavior.

  • Food, water, air, light, minerals, or other nutritional or physiological requirements.

  • Cover or shelter.

  • Sites for breeding, reproduction, and rearing of offspring.

  • Habitats that are protected from disturbance or are representative of the historical geographic and ecological distributions of a species.

In addition, according to its Endangered Species Listing Handbook (USFWS 1994), the agency considers both species and habitat dynamics when determining critical habitat. If the species requires ephemeral habitats, for example, the designation should consider the potential location of future habitats. Unoccupied areas may be included in critical habitat if, for example, they provide landscape connectivity between occupied areas, support pollinators or organisms involved in seed dispersal, or provide areas into which the population might need to expand (Fed. Regist. 68 (151): 46715 [2003]). However, the handbook directs the service not to include areas that are unsuitable for use by the species unless they are essential to conservation of the species (Figure 3-1).

Critical habitat determination may be most difficult where more territory is occupied at the time of designation than is necessary for the survival and recovery of the species. The statute and USFWS regulations and guidance provide little indication of how the agency will identify critical habitat within the occupied range. That identification raises issues of equitable distribution of the economic and other impacts of species protection and scientific issues of what is best for the species. One recent critical habitat determination states that the agency set priorities for designation among areas that were already subject to some protection and areas with minimal habitat fragmentation (Fed. Regist. 68 (151): 46684 [2003]).

The description of critical habitat is supposed to include a list of the physical and biological features essential to the species, which are referred to as primary constituent elements (50 CFR 424.12(b)). Management of critical habitat focuses only on those features (50 CFR 17.94(c)), and critical habitat designation therefore does not limit actions in a designated geographic area that do not affect the primary constituent elements (Fed.

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
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FIGURE 3-1 An example reach of the central Platte River with suitable habitat for whooping crane, piping plover, and least terns. This reach, near Shelton has substantial open areas with long sight lines. Source: Photograph by W.L. Graf, August 2003.

Regist. 68 (151): 46684 [2003]). Primary constituent elements are often only vaguely articulated in the critical habitat rule. A federal district court has held that identifying as primary constituent elements for the Rio Grande silvery minnow only water of “sufficient” quality and quantity did not provide an adequate standard (Middle Rio Grande Conservancy District v. Babbitt, 206 F. Supp. 2d 1156 [D. N.M. 2000]). Another federal district court has rejected a general description that the species requires a “suitable range” of temperatures or habitat patches of “sufficient size” to prevent isolation (Home Builders Association of Northern California v. USFWS, 268 F. Supp. 2d 1197 [E.D. Cal. 2003]).

Like listing decisions, critical habitat determinations must be made “on the basis of the best scientific data available.” A recent General Accounting Office report concluded that critical habitat designations generally do rest on the best available science, but the available data are often narrowly limited (GAO 2003). In contrast with listing decisions, however, critical habitat designation must also take into consideration “the economic impact, and any other relevant impact,” of that designation. Areas may be excluded from critical habitat if the agency concludes that the benefits of exclusion outweigh the benefits of inclusion unless it finds, on the basis of

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
×

the best scientific data available at the time of determination, that exclusion will result in the extinction of the species (ESA § 4(b)(2)).

Until recently, USFWS used a “baseline approach” to economic analysis, considering only the economic impacts imposed specifically by critical habitat designation and excluding the baseline economic impacts resulting from the listing of the species. Because, as explained below, USFWS believes that critical habitat designation has virtually no effect beyond that of listing, this approach greatly simplified the economic analysis of critical habitat designation. In most cases, USFWS found that critical habitat designation would have no economic effects beyond the baseline effects of listing. In 2001, however, a federal appeals court ruled that the baseline approach was unlawful (New Mexico Cattle Growers Association v. U.S. Fish and Wildlife Service, 248 F.3d 1277 [10th Cir. 2001]). Consequently, USFWS now considers all economic impacts, including ones that are coextensive with the impacts of listing, when it designates critical habitat. In its economic analyses, USFWS attempts to forecast all costs of conducting Section 7 consultations (discussed below) with respect to the species and costs of revising or forgoing projects on the basis of the consultations.

USFWS recently began making aggressive use of the authority to exclude areas from critical habitat on the grounds that the benefits of exclusion outweigh the benefits of inclusion. This practice has not yet been tested in litigation. The agency has not articulated a general process for determining when such exclusions are appropriate; instead, it makes exclusions on an ad hoc basis. In one recent decision, it excluded entire counties in California from critical habitat for a number of vernal pool species because it determined that the costs imposed by including habitat in those counties would be disproportionately high compared with costs imposed in other areas and for other species (Fed. Regist. 68 (151): 46745 [2003]).

USFWS also has taken the position that areas can be excluded from critical habitat designation if they do not require special management. It excludes areas from critical habitat as adequately managed if a management plan or agreement that is in effect provides sufficient conservation benefit to the species, it provides adequate assurances that its conservation strategies will be implemented, and it provides sufficient assurances—for example, through monitoring and revision procedures—that the strategies will be effective (Fed. Regist. 66 (22): 8543 [2001]). A federal district court has recently held, however, that the ESA does not permit exclusion from critical habitat on the grounds that adequate management provisions are already in place (Center for Biological Diversity v. Norton, 240 F. Supp. 2d 290 [D. Ariz. 2003]). In recent critical habitat determinations, USFWS has relied on a different basis for excluding managed areas. The statute provides that any area may be excluded from critical habitat if the benefits of exclusion outweigh those of inclusion, provided that exclusion will not

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
×

cause the extinction of the species (ESA § 4(b)(2)). The agency’s current interpretation is that where lands are already managed for conservation of the species, the benefits of critical habitat designation are minimal and therefore easily outweighed by the potential resource costs and delays imposed by the consultation requirement. USFWS treats this basis of exclusion from critical habitat as broader than the “no special management required” criterion, such that it allows exclusion even in the absence of an approved management plan (Fed. Regist. 68 (151): 46751 [2003]).

The ESA requires designation of critical habitat “to the maximum extent prudent and determinable” at the time a species is listed (ESA § 4(a)(3)). According to agency regulations, designation is not prudent if it would increase the threat of deliberate human taking or it “would not be beneficial to the species” (50 C.F.R. 424.12(a)(1)). USFWS once took a very broad view of the “not prudent” exception, frequently declining to designate critical habitat because it would provide little incremental protection beyond that provided by listing alone. Several court rulings, however, have required the agency to make a more specific showing that the benefits of critical habitat designation are outweighed by specific threats to the species, such as the threat of increased collection activity, if it wants to invoke the “not prudent” exception (e.g., Natural Resources Defense Council v. U.S. Dept. of Interior, 113 F.3d 1121 [9th Cir. 1997], Sierra Club v. USFWS, 245 F.3d 434 [5th Cir. 2001]).

Critical habitat is not determinable when the impacts of designation cannot be analyzed or the biological needs of the species are not sufficiently well known to permit identification of an area as critical habitat (50 CFR 424.12(a)(2)). Because so little is known about many dwindling species, identifying critical habitat at the time of listing often poses a serious challenge. For that reason, commentators, including a National Research Council committee, have proposed that short-term “survival habitat” be the focus at the time of listing, leaving the detailed identification of critical habitat and the accompanying economic evaluation for the recovery-planning process (NRC 1995). The statute, however, sharply limits delay while additional information is developed. USFWS can delay designation for only 1 year on the grounds of lack of information (ESA § 4(6)(C)(ii)). At the end of that year, it must designate critical habitat on the basis of the available data.

USFWS has long believed that designation of critical habitat is “an expensive regulatory process that duplicates the protection already provided by the jeopardy standard” (Fed. Regist. 64 (113): 31871 [1999]). In recent years, USFWS has been, in its words, “inundated with citizen lawsuits” based on its failure to designate critical habitat (Fed. Regist. 64 (113): 31872 [1999]). In response to the deluge of critical habitat lawsuits, the U.S. Department of the Interior (DOI) has requested and Congress has

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
×

approved a cap on spending on critical habitat determination to ensure that critical habitat work does not consume the entire ESA listing budget. During the summer of 2003, the assistant secretary of the interior for fish and wildlife and parks testified that the flood of critical habitat litigation was preventing USFWS from adding deserving species to the protected list and was delaying recovery efforts for already-listed species.

Once designated, critical habitat may be revised as new data become available, but there is no specific requirement for periodic revision. The listing agencies are required to review the status of listed species every 5 years to determine whether they should be delisted or their classification should be changed (ESA § 4(c)(2)). If review shows that critical habitat should be revised, USFWS has said that it “will take appropriate action” (Fed. Regist. 45:13010 [1980]). However, USFWS has no funding even for new critical habitat designation. It is highly unlikely that the agency would choose to revise existing critical habitat designations in the current budget climate even if specifically asked to do so. In recent years, when USFWS has found critical habitat designation warranted in response to petitions, it has not proposed revisions. Nonetheless, there may be limits to the discretion that USFWS enjoys to delay revisions of critical habitat. In a case involving the Cape Sable seaside sparrow, a federal court has ruled that USFWS cannot indefinitely delay critical habitat revisions when, in response to a petition, it has acknowledged that revisions are necessary to adequately protect a critically endangered species. The court did not set a timetable for revisions but required USFWS to set and explain a schedule for making them (Biodiversity Legal Foundation v. Norton, 285 F. Supp. 2d 1 [D.D.C. 2003]).

Designation of Critical Habitat for Platte River Species

Several areas in the whooping crane’s migratory pathway, including the main channel of the Platte River, and its immediately associated riparian habitat between junction of U.S. Highway 283 and Interstate 80 near Lexington to the interchange for Shelton and Denman, Nebraska, were designated as critical habitat for the whooping crane in 1978 (Fed. Regist. 43:20938 [1978]) before addition of the statutory definition of critical habitat to the ESA. USFWS later proposed to designate several additional critical habitat units, including a portion of the Niobrara River and several national wildlife refuges in North Dakota and South Dakota (Fed. Regist. 43:36588 [1978]), but that proposal was withdrawn (Fed. Regist. 44:12382 [1979]). At the time of critical habitat designation for the whooping crane, USFWS was applying its regulatory definition, which focused on areas and elements whose loss would appreciably decrease the likelihood of the survival and recovery of the species. With respect to the Platte River unit,

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
×

USFWS noted that this area “forms the most important stopping site on the migration route of the whooping crane” (Fed. Regist. 40:58308 [1975]):

Historical data show that this area, sometimes called the “Big Bend” area of the Platte River, was a focal point through which the whooping cranes passed before spreading out to their wintering grounds to the south and their breeding grounds to the north. There are more old records of the presence of the species here than in any other part of the migration route, and recent confirmed records indicate continued heavy use within the last few years. Available information indicates that the combination of the Platte River channel, and adjacent wet meadows, rainwater basins, and farmlands form a unique association of habitats that is the most valuable part of the entire migration route of the species. Reduction in the quality or size of this habitat association, especially in the water level of the area, could be expected to have an adverse effect on the surviving population of the species.

When the piping plover was listed, USFWS indicated that critical habitat was not determinable. A lawsuit later resulted in a court order that required USFWS to designate critical habitat. In response to that order, USFWS issued a final rule that designated critical habitat for the northern Great Plains population of the piping plover on September 11, 2002 (Fed. Regist. 67 (176): 57638 [2002]) and that stated:

Within the geographic area occupied by the species … we designate only areas currently known to be essential. Essential areas should already have the features and habitat characteristics that are necessary to conserve the species. We will not speculate about what areas might be found to be essential if better information becomes available, or what areas may become essential over time. If the information available at the time of designation does not show that an area provides essential life cycle needs of the species, then the area should not be included in the critical habitat designation.

At the same time, USFWS recognized that habitats and species are both dynamic. It stated that “critical habitat designations made on the basis of the best available information at the time of designation will not control the direction and substance of future recovery plans, habitat conservation plans, or other species conservation planning efforts if new information available to these planning efforts calls for a different outcome.”

The primary constituent element identified for the critical habitat for the piping plover is “the dynamic ecological processes that create and maintain piping plover habitat.” On rivers, the primary physical constituent elements were identified as “sparsely vegetated shoreline beaches, peninsulas, islands composed of sand, gravel, or shale, and their interface with the water bodies.” A total of 19 units were identified as critical habitat for the piping plover, ranging across five states and covering a total of over 180,000

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
×

acres (over 74,000 ha) and 1,200 river miles. In Nebraska, the Platte River was designated as critical habitat for the piping plover from Lexington to the confluence with the Missouri River, a distance of 252 mi. The entire Loup River (68 mi) and the eastern portion of the Niobrara River (120 mi) were also designated. USFWS recognized that some of this area might not be occupied in any given year but stated that “designation is necessary because of the dynamic nature of the river. Sandbar habitats migrate up and down the rivers resulting in shifts in the location of primary constituent elements.” USFWS excluded the shoreline of Lake McConaughy from its critical habitat delineation on the grounds that it was already adequately managed under plans developed by the Central Nebraska Public Power and Irrigation District. It also excluded sand pits on the grounds that they do not meet the physical and biological requirements of critical habitat.

No critical habitat has been designated for the interior least tern or pallid sturgeon. When it listed the interior least tern, USFWS concluded that designation of critical habitat was not prudent, because it would provide no demonstrable overall benefit to the tern (Fed. Regist. 50:21790 [1985]). When it listed the pallid sturgeon, USFWS found that designation of critical habitat was not prudent and that critical habitat was not determinable (Fed. Regist. 68 (151): 46684 [2003]).

Regulatory Provisions of Endangered Species Act and Effect of Critical Habitat

Given current regulatory definitions, the designation of critical habitat has little, if any, direct regulatory impact. Nonetheless, critical habitat has frequently been a flashpoint for controversy. Objections to critical habitat designation seem to rest in part on misunderstanding of its legal significance, but may also have some justification. Apart from its narrow direct impacts, critical habitat designation may have indirect regulatory impacts. In a practical sense, it may affect the attitudes of regulators, federal agencies, and property-owners or resource-users, subtly altering the regulatory landscape. In addition, the current regulatory definitions have been rejected by one federal court and may eventually have to be revised.

Species listed as endangered or threatened under the ESA benefit from the two major regulatory provisions of the act: Section 7 and Section 9. Section 7 requires that federal agencies carry out programs for the conservation of listed species and ensure that the actions they take, fund, or authorize are not likely to jeopardize the continued existence of any listed species or to result in the destruction or adverse modification of designated critical habitat. Section 9, which applies to both federal and nonfederal actors, prohibits the taking of endangered and threatened animal species unless USFWS produces a special rule allowing limited take. Section 10

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
×

allows USFWS to authorize, by permit, acts that would otherwise be prohibited by Section 9 if the applicant submits an acceptable habitat conservation plan (HCP). A permit can be granted if the take is incidental to and not the purpose of the permitted action, the impacts will be minimized and mitigated to the greatest extent practicable, adequate funding to implement the plan is ensured, and the taking will not appreciably reduce the likelihood of survival and recovery of the species in the wild (ESA Section 10(a)(2)(B), 16 USC 1539(a)(2)(B)).

Critical habitat plays a direct role only in the operation of Section 7: federal actions must neither cause jeopardy nor destroy or adversely modify critical habitat. Section 7 is implemented through a process of formal or informal consultation. A federal agency whose actions may adversely affect a listed species must seek formal consultation with USFWS. The action agency prepares a biological assessment, detailing what it believes will be the impacts of its action. USFWS reviews the biological assessment and issues a biological opinion that the action will or will not jeopardize the continued existence of the species or destroy or adversely modify designated critical habitat (50 CFR Part 402). Jeopardy opinions must suggest any reasonable and prudent alternative (RPA) that will serve the purpose of the proposed action without causing jeopardy or adverse modification (ESA Section 7(b), 16 USC 1536(b)). The ultimate decision of whether the proposed action will cause jeopardy or impermissible effects on critical habitat remains with the action agency, which must use the best scientific data available at the time of the decision (ESA Section 7(a)(2), 16 USC 1536(a)(2)). But an agency that rejects the views of USFWS and proceeds with a project acts at its own peril. As the formal view of an agency with recognized expertise, a biological opinion carries considerable weight with a reviewing court.

Consultation can be a time-consuming and expensive process. It would be unusual, however, for critical habitat designation to increase the scope of the consultation requirement. Consultation is required for any action that may adversely affect a listed species. A biological assessment is generally required if a listed species may be present in the action area (50 CFR § 402.12), whether or not the action is within designated critical habitat. If the biological assessment results in the conclusion that the action may adversely affect the listed species or its critical habitat, formal consultation leading to a biological opinion is required (50 CFR § 402.14). Because effects on the species and its critical habitat are closely intertwined, it is hard to imagine a situation in which the critical habitat could be adversely affected without any adverse effect on the species.

Substantively, as a matter of law, the presence or absence of critical habitat currently makes little difference in the outcome of Section 7 consultations. USFWS has by regulation defined the “jeopardy” and “adverse

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
×

modification” prongs of Section 7 so that they are virtually identical. An action is considered to jeopardize the continued existence of a species if it “reasonably would be expected, directly or indirectly, to reduce appreciably the likelihood of both the survival and recovery of a listed species in the wild by reducing the reproduction, numbers, or distribution of that species” (50 CFR § 402.02). An action is considered to destroy or adversely modify critical habitat if it “appreciably diminishes the value of critical habitat for both the survival and recovery of a listed species” (50 CFR § 402.02). A federal appeals court ruled in 2001 that the regulatory definition of destruction or adverse modification of critical habitat is inconsistent with the ESA, and therefore invalid, because Congress must have intended the “adverse modification” prong of Section 7 to provide protection additional to that provided by the “jeopardy” prong (Sierra Club v. USFWS, 245 F.3d 434 [5th Cir. 2001]). That decision is binding on USFWS only within the Fifth Circuit, which includes Louisiana, Mississippi, and Texas. In that circuit, USFWS has not yet formulated an official response to the decision. Outside the Fifth Circuit, USFWS continues to apply the challenged regulation while it is under review (Fed Regist. 68 (151): 46684 [2003]). If USFWS revises its regulations, critical habitat designation could have some additional substantive regulatory consequences.

In addition to its direct regulatory effects, critical habitat designation could conceivably have indirect effects that might account for some of the opposition to designation. The process of designating critical habitat requires a close examination of the ecological needs of the species. It may alert USFWS to the potential for a variety of actions that adversely affect the species and to areas that may be essential or desirable for the recovery of the species. With respect to federal actions, the consultation process should produce much the same kind of information. But those who might be affected by conservation efforts may fear any process that generates information about the conservation needs of a species. They may worry, for example, that federal agencies will choose to implement conservation efforts beyond those required to avoid jeopardy or adverse modification of critical habitat under the authority of ESA Section 7(a)(1), which directs all federal agencies to carry out programs for the conservation of listed species.

Critical habitat designation also could have some ramifications for nonfederal actions. It might make USFWS more sensitive to the possibility that specific actions could violate the take prohibition of Section 9. It could also make enforcement easier. The designation process might generate or unearth evidence or expert opinion that could be used to prove a violation of Section 9, and designation might help to persuade a jury that the area in question truly is essential to the species. Finally, by drawing attention to the importance of land or water for a listed species, critical habitat designation could affect the market price or marketability of land that is designated or

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
×

that depends for irrigation on water required to maintain critical habitat stream flows.

As a practical matter, whatever its legal significance, critical habitat designation might affect how USFWS implements the ESA. Most agency decisions are made in district and field offices by personnel who might not have up-to-date training and expertise in the legal nuances of critical habitat designation or implementation. Agency personnel may believe that they have stronger regulatory grounds for prohibiting activities that could affect the species inside critical habitat than outside it. On the basis of the formal designation of critical habitat, they might also believe that they are obliged to vigorously protect those areas, which have been deemed essential to the species. Field personnel making decisions for other federal agencies and for private entities may react similarly. They might not see litigation as a desirable strategy even if they think that USFWS is overprotective of critical habitat. As a result, critical habitat may carry substantially greater practical power than close analysis of the law would suggest. It might be treated in practice as a well-defined boundary, and activities, such as water diversion or cellular-phone tower construction, might be prohibited inside but permitted outside the boundary even if the potential impacts on the species appear quite similar. That practical effect, however, seems to be substantially weaker with respect to critical habitat related to river flows than with terrestrial habitat. It is practical to draw an effective boundary across terrestrial habitat, but that is much more difficult for rivers. Designation of a single reach of a river as critical habitat can affect management of water projects just as strongly, and in precisely the same ways, as designation of the entire river.

Recovery Planning and Implementation

ESA Section 4 requires USFWS to produce and implement a recovery plan for each listed species unless the agency finds that a plan will not promote the conservation (i.e., the progress toward recovery) of the species (ESA § 4(f)). Recovery plans are frequently prepared by teams of experts drawn from various federal agencies and academe. The plans must include, to the greatest extent practicable, a description of site-specific management actions needed to conserve the species; objective, measurable criteria for species delisting; and estimates of the time and money needed to achieve the plan’s recovery goals (ESA § 4(f)). USFWS tries to minimize the social and economic impacts of implementing recovery plans (Fed. Regist. 59:34272 [1994]). Achievement of recovery goals identified in the plans may be a signal that consideration for delisting is appropriate, but it is neither necessary nor sufficient for delisting to occur. Delisting requires USFWS to determine, based solely on the best available scientific data at the time, that a species no longer meets the statutory definition of endangered or threatened.

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
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Recovery plans have been produced for each of the listed species at issue in this report. The committee has taken the recovery goals in those plans at face value; we have not attempted evaluation of the scientific basis of the goals, which lies beyond our charge. Recovery plans provide a useful roadmap to recovery, at least under the state of knowledge at the time of their preparation. But the existence of a recovery plan does not guarantee recovery or even implementation of the steps outlined in the plan. Federal courts have been unwilling to force unwilling agencies to implement specific steps in recovery plans at specific times. Nonetheless, recovery plans often have substantial value for the species. The plans for the whooping crane and pallid sturgeon, for example, have been the basis of substantial expenditures and management activities on behalf of the species.

Endangered Species Act and Water Development in Platte River Basin

In recent years, a number of sharp conflicts have arisen over the implementation of the ESA in the context of operation of federal water projects. That those projects would be the nexus of such conflicts is not surprising. Freshwater fishes and other riparian species in the West are among the most endangered groups in the nation (e.g., Bogan et al. 1998; Ricciardi and Rasmussen 1999). Not coincidentally, most western rivers are overappropriated, with high demand for diversions from the instream flows that support riparian species. More than half of all species listed under the ESA are affected directly or indirectly by water-management projects (Losos et al. 1995), and a large proportion of water-management projects have a federal nexus. Federal water projects, which dot the arid West, are a frequent target of demands for operational changes to benefit listed species. It is generally easy to connect the projects to changes from historical hydrological patterns, which in turn may be clearly related to species declines. Furthermore, because operation of the projects is a federal action, an operating agency must consult regularly with USFWS under Section 7 (e.g., Rio Grande Silvery Minnow v. Keys, 333 F.3d 1109 [10th Cir. 2003]; Klamath Water Users Protective Association v. Patterson, 204 F.3d 1206 [9th Cir. 1999]) and make any changes necessary to avoid jeopardy. Even if a federal project is not responsible for all threats to the species, as is frequently the case, under Section 7 the operating agency must ensure that the project does not, in combination with those other threats, produce jeopardy or adverse modification of critical habitat (Pacific Coast Federation of Fishermen’s Associations v. U.S. Bureau of Reclamation, No. C 02-2006 SBA [N.D. Cal., July 15, 2003]).

Many new water projects or diversions are also subject to Section 7 consultation because they have a federal nexus even if they are not carried out by a federal agency. Many require a permit from the Army Corps of Engi-

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
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neers under Section 404 of the Clean Water Act or a license from the Federal Energy Regulatory Commission (FERC) under the Federal Power Act. Others are funded by a federal agency or require the use of federal lands.

The Platte River Basin, like many others in the West, has been the site of bitter ESA conflicts. In the Platte Basin, those conflicts began more than 25 years ago, when USFWS issued a jeopardy opinion for the proposed Grayrocks Dam on the Laramie River in Wyoming. Litigation over Grayrocks was settled with an agreement under which Basin Electric Power Cooperative constructed the dam with less storage capacity than originally proposed and funded creation of the Platte River Whooping Crane Critical Habitat Maintenance Trust. Jeopardy opinions were issued in 1983 for the proposed Narrows Project on the North Platte River, in 1994 for diversions on National Forest land in the Front Range, and in 1997 for relicensing of the Kingsley Dam hydroelectric project. Thereafter, between 1998 and 2001, USFWS issued a series of nearly 20 jeopardy opinions for activities that would affect the central Platte (USFWS 2002a). All those jeopardy opinions concluded that proposed depletions to the Platte River would both jeopardize the continued existence of listed species and adversely modify the critical habitat in the central Platte region. Even without the formal designation of critical habitat, therefore, the opinions would have required changes in the proposed activities. In this series of biological opinions, USFWS did not flatly prohibit the proposed diversions; instead, it included RPAs calling for the diverters to contribute money to an account to be used for acquisition and maintenance of habitat along the central Platte.

In a 2002 biological opinion, USFWS announced that it had “adopted a jeopardy standard for all Section 7 consultations on Federal agency actions which result in water depletions to the Platte River” (USFWS 2002a, p. 8). The service noted that over 1,000 projects contemplated in the basin, most involving annual depletions of 25 acre-ft or less, might require Section 7 consultation in the near future. It therefore issued a single biological opinion for all such small diversions, determining that they would not jeopardize the listed species or adversely affect designated critical habitat provided that they were accompanied by conservation actions, including either replacement of the depleted water or payment of a specified amount into a habitat-mitigation fund. In the 2002 biological opinion, USFWS noted that groundwater pumping in the Platte River Basin would further degrade the ecosystem and threaten the survival and recovery of the listed species (USFWS 2002a, p. 57). Without further information, the service felt that it was not possible to predict how much groundwater depletion would occur in the action area. Because groundwater pumping generally does not have a federal nexus, it does not require consultation. However, USFWS must take the effects of groundwater depletion into consideration in Section 7 consultations on federal actions.

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
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Role of Science in Implementing Endangered Species Act

The ESA repeatedly calls for use of the best available scientific information. Listing decisions must be based solely on the best available scientific and commercial information (ESA Section 4(b)(1)(A), 16 USC 1533(b)(1)(A)). The designation of critical habitat must be based on the best scientific data available and consider the economic and other relevant impacts of designation (ESA Section 4(b)(2), 16 USC 1533(b)(2)). Federal agencies must use the best scientific data available in fulfilling their duty to ensure that their actions do not jeopardize endangered species or destroy critical habitat (ESA Section 7(a)(2), 16 USC 1536(a)(2)).

Legislative mandates, such as those in the ESA, requiring an agency to consider the best available scientific data in their decisions have at least two aims. First, they are intended to ensure that, to the extent possible, decisions are objective and unbiased. Second, they recognize that scientific knowledge is not static and require that agencies consult the state of the science at the time of their decisions rather than relying on possibly out-dated understanding. Those mandates do not, however, impose a requirement for some threshold level of certainty before agencies may act. On the contrary, in combination with the limited timeframes allowed for decisions under the ESA, they often require that an agency use its best judgment to choose a path on the basis of extraordinarily sparse information.

It is not clear how much the ESA’s explicit requirement that agencies use the best scientific data adds to the background requirement that agency decisions must not be arbitrary or capricious. Under the ESA, USFWS may not ignore existing data, but its interpretation of the data and its determination of whether some data are scientifically better than others are entitled to substantial deference from the courts. USFWS has a duty to gather existing evidence, but it has no duty to undertake new studies when the existing data are ambiguous or inconclusive. Many ESA decisions, including the determination of critical habitat and the issuance of biological opinions, are subject to fairly short statutory deadlines. To meet those deadlines, USFWS often must make decisions without conclusive evidence and base its decisions on its best interpretation of the evidence available.

To implement the requirement that it consider the best available scientific data, USFWS has issued a policy detailing how it will treat information under the ESA (Fed. Regist. 59:34272 [1994]). The policy requires, among other things, that agency scientists gather and impartially evaluate information, including information that disputes official positions; document their evaluation; and use primary and original sources when possible.

Although it repeatedly requires the use or consideration of the best available scientific data, the ESA does not require that agencies treat the data precisely as research scientists would. In particular, the burden of

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
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proof under the ESA is not necessarily the same as the burden of proof in the scientific community. Research scientists typically apply a stringent standard of proof, requiring 95% certainty before they will accept that a given event causes an observed result. That convention serves scientific purposes, but it is not necessarily appropriate for decisions under the ESA. Indeed, Section 7 of the ESA itself suggests a less stringent standard of proof: federal agencies are directed to “insure” that their activities “are not likely” to cause jeopardy or adverse modification of critical habitat. The Endangered Species Consultation Handbook developed by USFWS requires that the species be given the benefit of the doubt when a biological opinion must be completed in the face of substantial data gaps (USFWS and NMFS 1998). In practice, because the ESA is not highly specific about standards for listing, critical habitat determination, or jeopardy opinions and because courts are strongly inclined to defer to the agency’s technical determinations, USFWS enjoys substantial discretion to determine the acceptable extent of risk and the degree of confidence that the available scientific information must provide.

Water Law in Platte River Basin

In the Platte River Basin, the ESA is implemented against a background of state water law because the suitability of the Platte River as habitat for the listed species is largely a function of operation of federal water projects upstream and the removal of water from the river for irrigation. In general, if there is a conflict between federal or state water law and the ESA, the ESA will prevail. Water law in the basin is important, though, because it has shaped the expectations of water users, and it can determine which of various possible solutions to ESA problems in the basin appear best to the parties involved.

The waters of the Platte River system arise in Colorado and Wyoming, flow into Nebraska in the North and South Platte Rivers, combine to cross most of the state in the Platte, and eventually empty into the Missouri River on Nebraska’s eastern border. All three states, like most western states, use the appropriative system for allocating surface water. The natural flow of the Platte River and its tributaries was fully appropriated before 1900.

The waters of the South Platte were apportioned between Colorado and Nebraska by interstate compact in 1923. The North Platte is not subject to a compact; instead, it has been the subject of prolonged litigation. Its waters were equitably apportioned among Wyoming, Colorado, and Nebraska by the U.S. Supreme Court in 1945 (Nebraska v. Wyoming, 325 U.S. 589 [1945]). The Court left open the possibility of modification in light of changed circumstances. In an action begun in 1986, Nebraska sought modification to require (among other things) that Wyoming and Colorado supply additional

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
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water for habitat protection. The United States, because of U.S. Bureau of Reclamation (USBR) projects in the basin, was also involved in this suit. After many years and two interim Supreme Court opinions, many aspects of the dispute were finally settled in 2001. The settlement capped irrigation withdrawals from the North Platte system in Wyoming, including both surface-water diversion and pumping of hydrologically connected wells; called for Wyoming to transfer its habitat-mitigation lands in the central Platte to USFWS once storage has been increased in Pathfinder Dam; allocated the available waters of the USBR North Platte Project between the states in low-water years; and created an interstate committee to monitor compliance with its terms. The settlement did not resolve the issue of flows for wildlife or habitat, however, because the parties agreed that those issues were better addressed through the cooperative agreement process, discussed below. The Supreme Court approved the settlement and issued a new decree incorporating its terms, again subject to modification if conditions change (Nebraska v. Wyoming, 534 U.S. 40 [2001]).

Nebraska allows appropriation of instream-flow rights (Nebraska Revised Statutes §§ 46-2,107–46-2,119 [1984]) but only to the extent necessary to maintain the instream uses for which appropriation is requested, such as protection of habitat for aquatic species. Because recognition of instream-flow appropriations is a recent phenomenon, instream-flow rights are junior to existing surface-water appropriations.

Nebraska does not require appropriative permits for development of groundwater. As a default matter, landowners have the right to remove groundwater. Whereas the state Department of Natural Resources is responsible for surface-water allocation, local natural-resource districts have the authority to regulate groundwater pumping (Nebraska Revised Statutes 46-656.25). Most natural-resource districts have not implemented any groundwater pumping restrictions. Many observers expect that full implementation of the cooperative agreement will likely lead to regulation of groundwater pumping in Nebraska (Aiken 1999; Sax 2000).

Nebraska has a state statute that protects endangered species: the Nebraska Endangered Species Conservation Act (NESCA), adopted in 1975 and closely patterned after the federal ESA (Aiken 1999). The NESCA provides that federally listed species that occur in Nebraska shall be protected under Nebraska law (Nebraska Revised Statutes 37-806 [1998]). Therefore, all the federally listed species in the Platte River Basin are also protected by state law. The NESCA, however, allows the Nebraska Game and Parks Commission (NGPC) to identify critical habitat independently of any federal designation (Nebraska Revised Statutes 37-807 [1998]).

The NESCA requires the Department of Water Resources to consult with the NGPC before approving applications to appropriate water. Applications must be denied if the department concludes that granting them will

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
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jeopardize the continued existence of a listed species or destroy or modify critical habitat (Nebraska Revised Statutes 37-807 [1998]). In the middle 1990s, the department denied an application by the Central Platte Natural Resources District to construct a diversion dam at Prairie Bend, in part because the area was in the critical habitat designated by USFWS and the department concluded that the dam would alter the habitat in a way that would be detrimental to the whooping crane. The state Supreme Court upheld the determination (Central Platte Natural Resources Dist. v. City of Fremont, 250 Neb. 252 [1996]), and a concurring judge noted that the state act allows the department to “err on the side of caution” (id. at 268-69, White, C.J., concurring). Aiken (1999) details a number of instances in which the state agency has denied applications for diversions from the Platte River on the basis of impacts on endangered species or their habitat.

Platte River Cooperative Agreement

The series of jeopardy opinions on Platte River diversions, in particular the drawn-out relicensing proceedings for Kingsley Dam, drove the basin states and DOI to enter into a cooperative agreement in 1997. The agreement is overseen by a Governance Committee consisting of one representative of each state, two federal representatives (one from USFWS and one from USBR), two representatives of environmental interests, and three representatives of water users (one from the North Platte, one from the South Platte, and one from downstream of Lake McConaughy). The purpose of the agreement is to implement elements of the recovery plans for the central Platte species in a manner that will prevent future jeopardy opinions for existing and new water-development activities.

The parties have committed to increasing flows by 130,000-150,000 acre-ft per year at Grand Island and protecting or restoring 10,000 acres of habitat in the central Platte region by 2010 (Cooperative Agreement, Attachment 3). The agreement commits USFWS to recommend specific RPAs for new activities with a federal nexus that will deplete the Platte River. For depletions of 25 acre-ft or less per year, USFWS will recommend replacement of the water or payment of a mitigation fee determined by a formula that it developed in 1996. For depletions of more than 25 acre-ft, USFWS will recommend replacement within the state of the diversion, outside the irrigation season, at a time of shortage for the species. All consultations for such activities, however, remain subject to reinitiation if a full program is not implemented. The terms of the cooperative agreement have been incorporated in the 1997 biological opinion on renewal of the FERC license for Kingsley Dam and all later biological opinions.

The cooperative agreement initially envisioned that within 3 years the Governance Committee would develop a long-term program and the

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
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program would go through the National Environmental Policy Act review process. It set specific milestones to be accomplished within the 3 years, such as development of a water-accounting system for depletions, including those from new groundwater wells, and identification of the impacts of activities undertaken under the cooperative agreement on the listed species. At the end of the 3 years, the program was far from completion. The parties agreed to extend the cooperative agreement to June 30, 2003. The program is still not complete, and it is unclear to the committee how many of the milestones have been met. The agreement has led to the creation of an Environmental Water Account encompassing 10% of the water stored in Lake McConaughy and to the postponement of a proposed diversion project in Wyoming (Sax 2000).

The intent of the agreement is to develop a long-term program that will provide certainty with respect to future water development and will facilitate recovery of the listed species. The 130,000-150,000 acre-ft annually promised in the initial phases of the agreement are likely to prove far less than what is ultimately needed to recover the species, but the federal agencies viewed implementation of the program as sufficiently valuable to justify limiting demands for additional water during the first increment period (Sax 2000). The full program is supposed to identify and provide for the amount of added flow that will be needed by the species in the long term. If the program never materializes, USFWS will be forced to return to project-by-project Section 7 consultation, and it will probably impose more onerous conditions as RPAs.

SCIENCE AND UNCERTAINTY

This report was solicited in large part in response to controversy attending the use of available information by USFWS in its designation of critical habitat for listed species found in the central Platte River and its recommendations for instream flows. We have been asked to assess the underlying scientific basis of agency decisions that have substantial economic and social implications. At issue is the quality of the data used in decisions and whether those data have been appropriately interpreted and applied. More specifically, we have been tasked to examine the scientific foundations of a number of conclusions that relate the habitat needs of species to river operations. Use of the term science in this regard requires clarification. It is also important to remember that science need not be the decisive factor in environmental-management decisions. Those decisions are sometimes based on costs, values or political preferences, experience, assumptions, or any combination of those. Management of threatened and endangered species in the Platte must rest to some extent on evaluation of scientific data. The federal ESA requires that many decisions—including

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
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listing, designation of critical habitat, and evaluation of jeopardy—take into account the best available scientific evidence. That does not mean, however, that science does or even can prescribe all the management choices for those species.

Data Collection and Evaluation

Science is a process, not an outcome or a product. At its most formal, the process has two major steps: gathering of data designed to differentiate among alternative explanations of phenomena of concern; and communication of the methods used, data gathered, and analysis and interpretation of the data for review by the relevant community of peers. Through an iterative process of data-gathering, communication, and re-evaluation, scientists can generate increasingly robust explanations of how physical, chemical, and biological systems function; how species behave and interact in those systems; and how manipulation of environmental conditions is likely to affect species and ecological communities. By making their results and interpretation public, scientists allow others to verify and build on their work. Because science is a process, scientific knowledge and the solidity of scientific conclusions are expected to advance with time and additional work. Scientific conclusions are always contingent, subject to modification or re-evaluation as more data are gathered and more hypotheses are tested.

Data derived from experimentation in controlled systems, as in laboratories, can provide the strongest evidence in favor of or against a hypothesis because potential confounding factors can be eliminated. But such controlled experimentation is often impractical or impossible in large natural systems. Therefore, scientists necessarily and legitimately rely on other kinds of data to understand such systems. Only very rarely do data derived from controlled experiments clearly resolve issues in species conservation.

Models can be useful tools in conservation planning, especially when data gaps make it difficult or impossible to answer management questions directly. Models are constructs of a system and are developed by application of basic principles to evaluate the effects of change in specified factors on the modeled system. Models may be simple or complex. They should clearly describe the input variables, algorithms, and calibration procedures that they use. Modeling algorithms can use statistical or deterministic approaches or can provide continuous simulations or estimates of steady-state conditions. The critical issues in model evaluation are whether scientific principles are appropriately used in model construction and whether the model is sufficiently transparent for all assumptions and manipulations to be apparent. Where feasible, model outputs should be evaluated through comparison with field measurements.

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
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Models are increasingly used in conservation planning for at-risk species. Population viability analysis (PVA), which has informed listing decisions, recovery plans, and habitat conservation plans under the ESA (Shaffer et al. 2002), uses demographic models to predict the likelihood of population persistence over a specified period under various circumstances, for example, where greater or smaller amounts of habitat are available, when qualities of habitats vary, under different magnitudes of mortality from diverse sources, or with varied reproductive success and offspring survival. PVA typifies both the value and limitations of using models to support policy and management decisions. Although it allows for explicit projections of population fates under real scenarios that imperiled species face, it is greatly constrained by the quality and quantity of available data, difficulties in estimation of parameters, and the usual lack of model validation. The committee references population viability model outputs in its assessments of whooping cranes, piping plovers, and interior least terns in Chapters 5 and 6, acknowledging both the reasonable inferences that can be drawn from the modeling efforts and assumptions that constrain application of the results. The PVA developed by the committee was constrained by the short study period. It did not include systematic sensitivity analyses and did not base stochastic processes and environmental variation on data from the Platte River region. A more thorough representation of environmental variation in the Platte River could be developed from regional records of climate, hydrology, disturbance events, and other stochastic environmental factors. Where records on the Platte River basin itself are not adequate, longer records on adjacent basins could be correlated with records on the Platte to develop a defensible assessment of environmental variation and stochastic processes. In addition, a sensitivity analysis could demonstrate the effects of wide ranges of environmental variation on the outcomes of PVAs.

To support management decisions—such as whether to list a species, where to designate critical habitat, or whether a proposed action will cross the jeopardy threshold—available data must be synthesized and applied. That requires the use of professional judgment. Professional judgment combines available data with professional knowledge of the systems or species in question on the basis of direct experience and knowledge of relevant scientific literature. Ideally, managers using their best professional judgment reject unreliable data, document their interpretations so that others can understand and evaluate the decision process, identify pertinent uncertainties, and clearly articulate the conclusions they draw. That decision-making process is not the classic process of “doing science.” Instead, it is “using science.” But it shares the underlying scientific commitment to comparing assumptions about the natural world with the available empirical

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
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data. Managers often must make their best guesses on the basis of sparse data. Their guesses are limited by the data available; to be consistent with professional practice, their judgments must be consistent with existing data and, at the next decision point, subject to reconsideration in light of any new evidence that becomes available.

Uncertainty and Decision Making

Uncertainty is typically high in the context of ESA decisions because available data are incomplete and environmental systems are inherently variable. Nonetheless, the ESA frequently demands that decisions be made quickly. Decision making in the face of uncertainty is familiar in a variety of other contexts, and some general methods for dealing with uncertainty have been developed.

Uncertainty can, in some cases, be well characterized and taken into account through mathematical formulas. Possible outcomes and their probabilities may be accurately understood. For example, before rolling a fair die, one cannot say for certain what the outcome will be, but the possible outcomes (a 1, 2, and so on) and their probabilities are not in doubt; there is a 1/6 probability of rolling any chosen number. Uncertainty of that type cannot be resolved by collecting additional information; but because the probabilities of the known events are understood, decision making and management are not unduly complicated. Because the behavior of environmental systems is far less regular than the behavior of a die, that type of uncertainty is not typical of environmental systems.

In other situations, the possible outcomes may be understood but their probabilities not precisely predictable. Weather forecasting is an example. Climate records that can be used to understand the variability of weather and the possible weather events may exist, but tomorrow’s weather, or even the probabilities of different outcomes, cannot be objectively determined. To arrive at weather predictions, forecasters might use extensive scientific data. Multiple scientifically valid models may be available to interpret the data. In some cases, results of different models might point in different directions. Forecasters combine the raw data and modeling results with their own professional experience and use their scientific and professional judgment to arrive at weather forecasts. Not surprisingly, different weather forecasters may arrive at different forecasts on the basis of the same information. In circumstances of uncertainty, appropriate use of the best available scientific data will not necessarily produce a single, universally agreed on result. Thus, the existence of disagreement does not establish that the best available data have not been used or that they have not been interpreted according to applicable professional standards.

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
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Adaptive Management

It may be possible to reduce uncertainty about the functioning of natural systems, and thereby to improve management decisions, through adaptive management. The concept of adaptive management encompasses a spectrum of practices designed to maximize learning and the feedback of new information into management decisions (Box 3-1). It can be done passively through the systematic collection and review of information about the effects of management actions or actively by designation of management actions as experiments. Whether and to what extent adaptive management should be used depends on the ability to learn, on the value of information that might be generated, and on whether latitude and resources are sufficient to allow alternative approaches to be implemented. Adaptive management and other forms of learning may reduce uncertainty; but in the context of conservation of endangered or threatened species, it will rarely be possible to eliminate uncertainty.

The committee believes that adaptive management—at least in the sense of careful data collection, evaluation, and periodic reassessment of management choices—could be useful for the management of Platte River species. Specific recommendations for monitoring and data-gathering are provided in Chapter 8. That information-gathering will serve little purpose if what is learned is not put to use in future management decisions.

BOX 3-1
Adaptive Management

Adaptive management for water resources is an approach that operates with a feedback mechanism. First, scientific information and explanations provide recommended behavior patterns for managers who desire to benefit given species in an ecosystem. For the Platte River, the recommendations might be for instream flows and variations in them to cause changes in the river channel to benefit threatened and endangered species. Management actions, such as the release of prescribed flows of water from a reservoir, are undertaken with particular ecosystem goals. In the case of the Platte River, releases might artificially simulate floods that occurred before dams were constructed on the river and might include some high flows to sweep away seedlings on bars and beaches, which would result in open sight lines and stopover locations for whooping cranes. Next, adaptive management requires monitoring of the system to determine whether the desired outcome has been achieved. For the Platte River, observations on the river channel might confirm the expected changes and increases in suitable habitat for whooping cranes, or they might reveal unexpected outcomes. Finally, adaptive management uses the observations from monitoring to fine-tune the original management plans to improve the outcomes. The committee endorses the concept of adaptive management as presented in NRC (2004 a,b).

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
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Scientific Validity

Scientific validity is a contextual determination. It may mean that a reasonable scientist in the field would accept a conclusion as justified in light of the evidence available. In some circumstances, specific conventions have been developed that require a specific level of certainty before a conclusion is accepted (e.g., a 95% confidence level). Those conventions rest on value judgments about the relative costs of false-positive and false-negative errors. The costs may be very different between the management context and the context of abstract scientific research. Moreover, because science is not fixed in time, neither are judgments regarding scientific validity.

The degree of scientific certainty needed to justify a particular management decision is a social decision that requires evaluation of the relative costs of different types of errors. The committee has not attempted to make those decisions, which we regard as outside our charge. Instead, we have tried to evaluate the strength of the scientific evidence supporting current management decisions (Box 3-2).

Data and Uncertainty in Implementation of Endangered Species Act

Scientific research and the knowledge it produces play important roles in the administration of the ESA. Answering the question of whether a species is endangered or threatened requires the use of scientific observation. Ecological analysis leads to an understanding of habitat needs. The development of recovery plans requires an understanding of why populations have declined so much that a species is threatened or endangered. Such research usually requires not only biological approaches to understand the dynamics of the species itself but also approaches that include earth, water, and atmospheric sciences to understand the changing physical basis of its habitat. USFWS and action agencies are required to use the best available scientific information in conducting consultations and in determining jeopardy opinions.

In the context of ESA implementation, available data typically are sparse, and what data do exist are usually derived not from laboratory experiments but from less-structured methods. Listing decisions, critical habitat designations, and biological opinions are usually informed by data from simple species surveys, counts of individuals at circumscribed locations through time, and observations of resource use, behavior, and reproductive success under varying circumstances. In a few cases, more complex and comprehensive studies that provide additional data on species behavior or biology, such as survival of offspring to maturity and long-distance dispersal, are available.

In addition to being sparse, available data often have been collected from diverse sources that can have varying reliability. Sources may range from observations by laypersons through systematic inventories undertaken by trained professionals to systematic development of dynamic process

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
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BOX 3-2
Criteria for Assessing the Degree of Scientific Support for Decisions

The charges to the Committee on Endangered and Threatened Species in the Platte River Basin generally required the committee to assess the degree of scientific support for decisions reached by Department of the Interior agencies regarding species and river processes. In determining whether and to what extent decisions are supported by existing science, the committee considered:

  • The extent of data available.

  • Whether the available data had been generated according to standard scientific methods that included, where feasible, empirical testing.

  • Whether those methods were sufficiently documented to allow others to repeat them and whether and to what extent they had been replicated.

  • Whether either the data or the methods used had been published in documents made freely available to other researchers and the public to facilitate criticism or correction and whether they had been formally peer-reviewed.

  • Whether the data were consistent with accepted understanding of how the systems function and whether they were explained by a coherent theory or model of the system.

  • Whether the decisions were publicly explained with clear reference to supporting data, models, and theories so that the rationale for the decisions was apparent and open to challenge by stakeholders.

No one of the above criteria is decisive, but taken together they provide a good sense of the extent to which any conclusion or decision is supported by science. Because some of the decisions in question were made many years ago, the committee felt that it was important to ask whether they were supported by the existing science at the time they were made. For that purpose, the committee asked, in addition to the questions above, whether the decision makers had access to and made use of state-of-the-art knowledge at the time of the decision.

The committee was also asked to assess the scientific validity of the methods used to develop instream-flow recommendations. The criteria applied in answering that question were similar to those above but focused more directly on methods:

  • Whether the methods used were in wide use or generally accepted in the relevant field.

  • Whether they had a sound theoretical basis or were supported by a generally accepted understanding of the system.

  • Whether they were sufficiently documented to facilitate replication.

  • Whether sources of potential error in the methods have been or can be identified and the extent of potential error estimated.

  • Whether the methods have been formally peer-reviewed or published in documents made freely available to other researchers and the public.

Again, no one criterion is decisive. Considering all those factors, the committee made a judgment as to the validity of the methods that it was asked to evaluate.

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
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studies carried out by scientists. Data-collection efforts typically are not commissioned or handled directly by resource managers; therefore, they often do not directly address key management questions. It can be expensive, time-consuming, difficult, or even impossible to collect directly the key data needed to address management questions.

The most popular method of organizing available data to assess the likelihood of species persistence is the aforementioned PVA, a modeling tool that uses information on genetic, demographic, and environmental sources of variability. The output of PVA is not an explicit prediction of time to population extinction but an estimate of the probability that a population of a given size will persist for some specified period. As in other fields of science, some uncertainty is inherent in PVA.

Scientific uncertainty pervades species-conservation issues, including those related to the central Platte River. Regan et al. (2002) term such uncertainty “epistemic.” Sources of epistemic uncertainty include survey shortcomings, measurement errors, variation and inherent randomness of the natural system and species responses, and the application of subjective judgment in the analysis and interpretation of available information. For the Platte River species, epistemic uncertainty is pervasive. The contribution of Platte River stopover resources to the fitness of individual whooping cranes can only be surmised through indirect data and subjective model assumptions; assessing the likelihood of regional persistence of Platte River piping plovers and interior least terns requires many assumptions about local structure and dispersal and about interactions among birds across larger landscapes; and information on the pallid sturgeon is virtually nonexistent beyond locations of capture, from which only the most basic inferences regarding habitat requirements and use can be made.

An additional challenge for the effective use of science in ESA regulatory decisions is that these decisions typically incorporate value judgments. The judgments have not been made either by Congress or by USFWS at a level specific enough to inform management decisions. Neither the ESA nor USFWS’s implementing regulations, for example, define threatened, endangered, or jeopardize the continued existence of in quantitative terms by identifying acceptable threshold levels of extinction risk. Nor do the statute and regulations specify how the agency should choose among occupied habitats, not all of which may be required to maintain a viable population, identify critical habitat, or determine what magnitudes of economic or other costs may justify exclusion of specific areas from critical habitat.

Those aspects of ESA implementation decisions are not scientific in the sense that they could, even in theory, be decided solely through evaluation of empirical, objectively gathered data. They require social or political value judgments that are inevitably subjective. The committee believes that these judgments should be made transparent; that is, USFWS should clearly

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
×

explain in a decision document both its evaluation of the scientific data and its use of nonscientific factors to reach a final decision.

WATER MANAGEMENT: CONNECTING LAW AND SCIENCE

The Platte River serves a large and growing urban population as a potable-water supply, provides water for irrigation of millions of acres of cropland, and provides habitat for a wide array of species, including some that are threatened or endangered. Competition for use of the Platte River’s waters has fueled serious debate within the basin states of Colorado, Wyoming, and Nebraska and beyond. To understand the details of the conflicts that have emerged in this watershed, it is useful to look at the forces that have created similar conflicts throughout the United States, and they are set forth here. The next section discusses some of the common elements of the conflicts and relates them to the Platte River controversy.

Overappropriation of Water

Many watersheds in the west are “overappropriated”; that is, more water has been legally allocated to users than can be physically provided in all years. There are many reasons for overappropriation, from lack of good technical information on which to base allocations to lack of political willingness to limit allocations (Meyers 1966). Perhaps the most famous example of overappropriation is the Colorado River, whose waters were allocated between upstream and downstream states by using data from one of the wettest periods in the last century. As a result, the Colorado River Compact allocates some 10% more water than is available in a typical water year.

Although the natural flow of the Platte River was fully appropriated before 1900, new uses of groundwater and surface water continue to be allowed. Surface-water and groundwater uses are necessarily connected; use of surface water beyond some point depletes hydrologically connected groundwater, and vice versa.

Changing Values and Public Perceptions

The values that the American public expects water management to serve have evolved over the last 50 years. Expanded focus on protecting endangered species, providing for recreational uses, and providing water supplies for Indian settlements have introduced major new pressures on river systems that were already overappropriated. Protecting these recently recognized values in the context of highly altered hydrological regimes increases possibilities for conflict.

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
×

In addition, public perceptions are often shaped by beliefs about natural systems that may not be based on adequate, defensible, or any empirical data. Entrenched ideological commitments complicate efforts to find compromise solutions or resolve conflicts collaboratively.

Institutional Inflexibility

The ability to solve problems in a changing physical and social context is affected by the ability of water-management institutions to respond to changes. Water-management institutions generally focus on protecting the status quo, including the rights of existing water users, and may not adapt quickly to changing circumstances.

Irreversible Decisions and Unacceptable Consequences

Many decisions in water management are effectively irreversible, and this limits the usefulness of adaptive management. For example, construction of a major dam is, as a practical matter, ecologically irreversible. The dam is unlikely to be removed in the short run; and although it might be removed at some distant time, it is likely to leave enduring effects on the landscape (Figure 3-2).

FIGURE 3-2 Keystone Diversion on the North Platte River, upstream from the central Platte River, represents an example of an effectively irreversible feature of the watershed that has enduring effects on flows. Source: Photograph by W.L. Graf, May 2003.

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
×

The Platte River system is already highly modified by the construction of dams, canals, and diversions that have important economic consequences. A large constituency has come to rely on the continued operation of those artifacts, but their environmental effects have only recently been recognized. It is not surprising that new water-management proposals have generated considerable concern among water and power interests.

Dispersed Costs and Concentrated Benefits

Federal water-planning guidelines typically forbid funding of new projects unless their benefits will exceed their costs. However, the costs of federal projects are spread among taxpayers nationwide, whereas the benefits typically are geographically concentrated. The concentration of benefits makes it possible to bring concerted political pressure to bear; such pressure has led in many cases to the development of water projects whose benefits do not exceed their costs. Historically, conflicts over the allocation of benefits and costs have been exacerbated by funding rules that provided full funding for some purposes (such as flood control) and less than full funding for others (such as municipal water supply).

Lack of symmetry between the costs and benefits of water projects can also contribute to pressures to maximize appropriations and diversions at the expense of environmental values (Farber and Frickey 1987). A nationwide constituency benefits, in a diffuse way, from the protection of endangered or threatened species and the other environmental values of river systems. In contrast, a focused, clearly identified community of water users benefits from diversion. Water users therefore typically find it easier than environmental interests to organize and exert political pressure on decision makers.

Evaluation of Cumulative Environmental Impacts

A difficult challenge encountered by water-resources planners and managers is how to evaluate cumulative environmental impacts (see NRC 1986, 2003). A classic example is the regulation of multiple discharges of waste into a single river. It is possible that none of the individual waste streams will threaten environmental values, but together they may produce unacceptably poor water quality. It can be difficult both to understand what total impact will pass acceptable threshold levels and to divide responsibility for avoiding unacceptable levels equitably. In the Platte, cumulative impacts include those of upstream activities (including withdrawals) in two other states and those of withdrawal of hydrologically connected groundwater.

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
×

Insufficient or Poor Data

As suggested previously, a primary source of conflict in water management can be the lack of information to support informed decisions. Although state and federal agencies historically collected an enormous amount of basic information concerning water resources across the United States, data-gathering efforts have recently been curtailed by funding concerns. Water-quality data are generally less available than water-quantity data. In general, data gaps leave a large number of uncertainties. As a result, decisions must be made under circumstances in which their environmental impacts, both favorable and unfavorable, are inapparent or difficult to predict.

Categories of Water-Resources Conflicts

The numerous water-resources conflicts across the United States can be categorized in a variety of ways, but one convenient approach is to define them in terms of water use. Conflicts frequently occur between upstream and downstream uses, instream and out-of-stream uses, groundwater and surface-water uses, and present and future uses. That categorization can help to create a framework for conflict resolution. The Platte River Basin today is experiencing all four types of conflict.

Perhaps the most common source of water conflicts is associated with upstream vs downstream uses. In many circumstances, water is diverted from a stream and only a portion of it is returned, leaving downstream users with less than the natural flow. Much of water law in the West, in particular the prior-appropriation doctrine, is devoted to providing a framework for resolving such conflicts. They are particularly intractable in larger watersheds, where the upstream and downstream uses may be separated by hundreds of miles and by state or international borders.

As water demands and water uses change, the character of upstream vs downstream water uses may change dramatically, increasing the potential for conflict. Disagreements between upstream and downstream states can be resolved by negotiation of interstate compacts or, if that fails, by litigation. The Platte has been the subject of both. The basin states successfully negotiated a compact for allocation of the waters of the South Platte, but the North Platte has been the subject of protracted litigation and is allocated largely by a court decree.

Conflicts between instream and out-of-stream uses in the West have increased dramatically since the 1970s, as water demands for municipal and agricultural uses have expanded and stresses on aquatic systems have been recognized. In some states, instream-flow rights have been established to protect water flows for biological communities. It is important

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
×

to note that until the 1980s, many states did not specifically recognize the public values of such flows, and maintaining flows for habitat was not guaranteed.

Quantifying ecological instream-flow requirements is often challenging in that anticipating the response of biological communities to a variety of flow regimes is difficult and estimating the effects of cumulative stressors on the biological communities is a young science. Two typical approaches are taken to establishing instream flows in rivers: establishing water rights based on a percentage of the natural flow on a monthly or weekly basis and providing minimal flows on the basis of the biological needs of a specific species. Instream flows have now been established for numerous rivers, often after one or more species have been identified as threatened or endangered or as part of a larger environmental licensing process (such as for hydropower production or municipal water supplies). Other users of water may view the establishment of such instream flows as direct threats to their access, noting that such requirements erode their ability to obtain water for out-of-stream uses. The flows that have been suggested by USFWS in the central Platte are examples of instream flows to protect endangered species, and there has been litigation over attempts by the NGPC to obtain instream-flow rights to support the central Platte’s endangered and threatened species.

Conflicts are increasingly emerging between surface-water and groundwater use. The relationship between surface water and groundwater was often ignored in early allocation of water rights. In some states, including Nebraska, surface water is regulated and groundwater remains largely unregulated. As described in the groundwater section of Chapter 2, the depletion of groundwater and its effects on surface flows have created substantial problems throughout the Southwest and elsewhere. Although the relationship between surface water and groundwater has been qualitatively understood for decades, legal and institutional constraints have impeded conjunctive management of these resources. The complicated hydrological relationship of surface-water and groundwater flows makes their regulation difficult, and often appropriate management can be achieved only after a detailed understanding of their interactions is obtained. The current efforts on the Platte to develop a comprehensive groundwater–surface-water model mark a good first step in developing a strong understanding of the hydrology of the river.

At the center of many water conflicts is the general notion of sustainability, which is related to the balance of present needs with future needs. Although many definitions of sustainability exist, a commonly used one from the Bruntland Report (Bruntland 1987) is “meeting economic, environmental and social needs of the present without compromising the ability of future generations to meet their own needs.” That definition is

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
×

especially appropriate for watershed planning because it goes beyond the simple allocation of today’s water to include the needs of people and the broader biological community for many generations into the future. The concept of sustainability is a broader management goal than resolving the individual categories of conflict mentioned above. However, a sustainable system must have a mechanism to address those conflicts.

Sustainability does not imply managing a watershed in a static fashion, that is, ignoring changes in water demands, water use, water availability, and the economic, environmental, and social systems that rely on water. It is difficult to imagine a sustainable system that is not “adaptive.” Adaptive management of watersheds—alteration of management of a watershed based on the system state and the current inputs and desired outputs of the system—may be required much more in the future as pressure on water supplies continues to increase.

LESSONS FOR THE PLATTE FROM OTHER WATER CONFLICTS

Every water-resources conflict can appear unique to those involved in it. Every watershed does have distinctive characteristics, but many of the causes of water conflicts and approaches to their solution are similar across a large number of basins. The components and categories of water-resources conflicts noted above are found again and again in other water-resources conflicts. Three lessons from water conflicts in the Colorado, Cedar, Klamath, and Snake Rivers are offered for those dealing with science and decision making for the Platte River.

The first general lesson is that uncertainty is always associated with the data available for decision making associated with water resources. Lack of complete data cannot be an excuse for making no decision; complete data will never be available. Adaptive management when incomplete data are available is an important hedge against mistakes derived from uncertainty, because in adaptive management, monitoring and measurement provide a constant stream of new data to evaluate the outcomes of decisions. If resource changes are not as expected, the new data can support revised decisions.

The second general lesson is that the level of uncertainty in the Platte River Basin is at least similar to that in other basins in the western United States. In some cases, the quality of data is better than in other circumstances, so although decisions are required in the face of incomplete data and some uncertainty, our scientific understanding of the Platte River and its resources provides support for decisions to a degree similar to the support for decision makers in other basins.

Finally, conflict resolution in water resources requires a comprehensive view of the entire watershed. The comprehensive view must take into

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
×

account the interests of all the stakeholders and economic sectors even if they are far removed from the site of intensive management. The comprehensive view of the watershed also dictates that downstream restoration and management are inescapably connected to management of the land and water resources in the upper watershed.

SUMMARY AND CONCLUSIONS

The issues faced in the Platte River Basin are similar to water-related conflicts in other parts of the United States. Protection of federal and state listed species in the central Platte River Basin has had, and will continue to have, a profound effect on management of the waters of the Platte River and many other rivers in the country. Critical habitat designation, which was the focus of the call for this study, however, has not been an important driving force in management decisions. Every biological opinion that has identified the need to restrict or modify federal actions in the Platte River Basin has found both that the proposed actions would jeopardize the continued existence of listed species and that they would adversely modify or destroy designated critical habitat. In other words, no biological opinion has said that the effects on critical habitat were unacceptable but there would be no jeopardy, and no biological opinion has ever relied solely on the effects on critical habitat to mandate changes in a project. USFWS’s views on the stream-flow and habitat needs of the protected species have been an important factor in management decisions, but the formal designation of critical habitat has not.

The best available scientific data are often incomplete or inconclusive, particularly in the context of endangered-species management, because information about the biological needs of species is difficult to gather and systematic data-collection efforts often are of recent origin. Management judgments may accord with professional standards and be considered scientifically valid even if they are made in the absence of conclusive data and even if they turn out to be wrong when judged against later-accumulated data. Science is a process of incremental learning, but managers do not have the luxury of waiting until conclusive evidence is accumulated; they are required to act on the basis of their best understanding of the system at any given time.

Many decisions made under the ESA, including decisions on critical habitat designation, cannot be fully determined with scientific data even if the data are complete. Those decisions require judgments about social values, including the relative importance of competing values at stake. Identification of endangered or threatened species requires choices about the level of acceptable risk. Designation of critical habitat requires some balancing of species’ needs against economic impacts—again, a determination of ac-

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
×

ceptable risk. In addition, when a species at the time of listing occupies a broader range than appears to be required to maintain a minimal viable population, critical habitat designation must include decisions about which areas to protect and which to allow to be destroyed. Those choices include scientific considerations, to the extent that some areas appear more important than others to the species, but also require balancing of equities with respect to competing human uses.

The uncertainty facing Platte River managers is high but not unusual for river systems in the United States. Furthermore, uncertainty about the Platte River is an element of all management decisions, not just decisions that restrict diversions. Just as there is uncertainty about stream-flow requirements of the listed species in the central Platte, there is uncertainty about the efficacy of the tradeoffs authorized by USFWS in its recent biological opinions authorizing new diversions in return for habitat-restoration efforts or payment of mitigation fees into a habitat acquisition and restoration fund.

Adaptive management is one approach for identifying and taking steps to close key information gaps. Adaptive management is being implemented, at least in small ways, in some other river systems. Platte River management might benefit from more-systematic efforts to accumulate data about the effects of flow levels on the physical and biological system and to incorporate the data into future management decisions.

Suggested Citation:"3 Law, Science, and Management Decisions." National Research Council. 2005. Endangered and Threatened Species of the Platte River. Washington, DC: The National Academies Press. doi: 10.17226/10978.
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The tension between wildlife protection under the Endangered Species Act and water management in the Platte River Basin has existed for more than 25 years. The Platte River provides important habitat for migratory and breeding birds, including three endangered or threatened species: the whooping crane, the northern Great Plains population of the piping plover, and the interior least tern. The leading factors attributed to the decline of the cranes are historical overhunting and widespread habitat destruction and, for the plovers and terns, human interference during nesting and the loss of riverine nesting sites in open sandy areas that have been replaced with woodlands, sand and gravel mines, housing, and roadways. Extensive damming has disrupted passage of the endangered pallid sturgeon and resulted in less suitable habitat conditions such as cooler stream flows, less turbid waters, and inconsistent flow regimes. Commercial harvesting, now illegal, also contributed to the decline of the sturgeon.

Endangered and Threatened Species of the Platte River addresses the habitat requirements for these federally protected species. The book further examines the scientific aspects of the U.S. Fish and Wildlife Service’s instream-flow recommendations and habitat suitability guidelines and assesses the science concerning the connections among the physical systems of the river as they relate to species’ habitats.

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