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1 Introduction
Pages 13-58

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From page 13...
... . These pollutants and other chemical and physical alterations have disrupted the ecosystem, causing degraded habitats and harmful algal blooms that impact the survival of fish, shellfish, and other aquatic life.
From page 14...
... 14 NUTRIENT AND SEDIMENT REDUCTION GOALS IN THE CHESAPEAKE BAY FIGURE 1-1 Chesapeake Bay Watershed.
From page 15...
... Water quality is evaluated according to three parameters that are linked to one or more of the Bay's habitats and faunal communities: dissolved oxygen, water clarity, and chlorophyll a. Criteria for these three water quality parameters serve as the basis for the current goals, spurring efforts to reduce nutrient and sediment loads.
From page 16...
... , primarily from other regions in the United States, and atmospheric deposition are important external sources of nitrogen to the Bay watershed. Atmospheric deposition of oxidized reactive nitrogen (NOy; the sum of nitric oxide [NO]
From page 17...
... supplemented by model estimates for ungaged portions of the watershed. The red lines indicate the 10-year average load targets for nitrogen and phosphorus (175 million pounds and 12.8 million pounds, respectively)
From page 18...
... with an eutrophication model (CE-QUAL-ICM) and computes the concentrations of nutrients and suspended sediment that result from the Watershed Model inputs, the quantity of phytoplankton that grow and decay, and the resulting water clarity and dissolved oxygen (DO)
From page 19...
... Loads are input to the Watershed Model to generate mod eled estimates of loads delivered to the Bay (EPA, 2010a)
From page 20...
... Steady state First coupling 4-month General goal of 40% Contained 5 land of watershed, summer of controllable loads uses, 64 segments hydrodynamic, simulation (CBP, 1987) and water quality only of 3 years models (1965, 1984, and 1985)
From page 21...
... .2 For the Bay itself, the primary internal source is biological nitrogen fixation. Nitrogen that originates from sources internal and external to the watershed is delivered to the Bay waters by atmospheric deposition, direct discharges from wastewater treatment plants and stormwater systems, and groundwater and riverine inputs.
From page 22...
... . Overall, how much denitrification occurs in the Bay watershed remains the largest uncertainty of the nitrogen cycle.
From page 23...
... NOTES: Based on model simulations using the Watershed Model Phase 4.3 and the Airshed Model, considering land use and pollution control measures in place as of 2007. The data reflects the average output when simulated over 14 years of hydrologic record and does not include loads from the ocean or tidal shoreline erosion.
From page 24...
... . Thus, the potential response times between land-based BMP imple mentation and significant resulting decreases in nutrient discharge from larger watersheds can vary widely based on watershed size, depth of water flowpaths, and relative contribution of groundwater to stream flow, which vary with physiographic provinces of the Bay Watershed.
From page 25...
... , after which legacy sediment nitrogen will not have a significant impact (Figure 1-6 Years Years FIGURE 1-6 Modeled response of Bay water quality to an abrupt 50 Figure 1-5.eps percent reduction in all loadings to the Bay for Zone 2 (200-250 km from the mouth of the bay) , Zone vector x-axis and Zone 6 (0-50km)
From page 26...
... . Other 4 For comparison, the CBP Watershed Model Phase 5.3 calculates that an average of 246 million pounds of nitrogen per year was delivered to the Bay based on 2009 land use scenarios when simulated over 21 years of hydrologic record (S.
From page 27...
... Deposition to the Chesapeake Bay Watershed and to the Chesapeake Bay by Source/Sector Percent of Atm. Deposition to Percent of Atm.
From page 28...
... Phosphorus Phosphorus occurs naturally in the soils and sediments of the Chesapeake Bay and its watershed, released slowly from mineral weathering and from decomposition of vegetation, with limited injection from the atmosphere. However, with growth in the human population and per-capita resource use, phosphorus has been introduced into the Bay watershed through the import of phosphorus fertilizer and of phosphorus-containing commodities, especially food and feed.
From page 29...
... . Based on a 2007 source-loading scenario simulated over 14 years of hydrologic record using Watershed Model Version 4.3, an average of 18.2 million pounds per year (8.3 million kg/year)
From page 30...
... . Effects of Excess Nutrient and Sediment Loads to Coastal Waters As with many estuaries throughout the world, one of the primary water quality challenges facing the Chesapeake Bay is cultural eutrophication -- a 5 For comparison, the CBP Watershed Model Phase 5.3 calculates that an average of 16.5 million pounds per year (7.5 million kg/yr)
From page 31...
... They reduce water clarity and block sunlight, reducing the size, quality, and viability of underwater grasses (also known as submerged aquatic vegetation [SAV]
From page 32...
... Similar to the effects of excess planktonic algae, clay and silt particles suspended in the water column block sunlight from reaching underwater grasses , resulting in reduced extent of these productive aquatic meadows. Reduced extent or elimination of underwater grasses can affect juvenile fish, blue crabs, and other aquatic life needing the vegetation for shelter to survive.
From page 33...
... . In 2003, the CBP established nitrogen and phosphorus cap loads for each major river basin and jurisdiction based on CBP model projections of attainment of dissolved oxygen water quality criteria.
From page 34...
... tributaries to meet applicable met standards for dissolved oxygen in Generally, higher levels of oxygen standards for dissolved oxygen 2007-2009 are needed in shallow waters during the spring, when aquatic animals spawn. Water clarity Adequate light to support 100% of the Bay to meet guidelines 26% of the Bay's tidal waters met or underwater grasses during the for water clarity exceeded guidelines in 2009 growing season.
From page 35...
... health to be at least 3 phytoplankton goal in 2009 to 5 (high) Oysters Oyster biomass Achieve at least a 10-fold increase 10% of goal achieved in 2008 in native oysters in the Bay by 2010, based on 1994 levels, which would equal 31.6 billion grams of oyster biomass Blue crab Number of blue crabs in the bay 200 million blue crabs that are 112% of goal achieved in 2009 at least 1 year old in the Bay Striped bass Female spawning stock biomass Spawning stock biomass equal to 148% of goal achieved in 2008 the averages from 1960-1971, which is 82.7 million pounds (37.5 million kg)
From page 36...
... . In 1987, the Executive Council signed a follow-up agreement to "reduce and control point and nonpoint sources of pollution to attain the water quality conditions necessary to support the living resources of the bay" and "plan for and manage the adverse environmental effects of human population growth and land development in the Chesapeake Bay watershed." In this agreement, the Executive Council set a specific goal of reducing the amount of nitrogen and phosphorus entering the Bay's main stem by at least 40 percent by the year 2000.
From page 37...
... The 2000 Chesapeake Bay Agreement provided an alternative to development of a TMDL, consistent with EPA regulations that allowed under TMDL priority "Category 4b" that a TMDL is not needed if other pollution control requirements are expected to result in the attainment of an applicable water quality standard in a reasonable period of time. The 2000 Agreement, signed again by the CBP partners, not yet including New York, West Virginia, or Delaware, acknowledged the difficulty of the management tasks facing them, including the management of nutrients.
From page 38...
... Progress made in each of these categories is detailed below. Activities to Preserve and Restore Natural Lands Because of growing population and land development within the Bay watershed, the CBP focused on land preservation and protection in the thousands of small watersheds within the Bay region.
From page 39...
... in the Bay watershed totaled approximately $327 million (J. Winters, EPA, personal communication, 2010)
From page 40...
... WWTP upgrades have accounted for a large portion of the estimated nutrient reductions in the watershed. As of 2009, 78 percent of the CBP's wastewater nitrogen reduction goals and 99 percent of its wastewater phosphorus reduction goals have been met (CBP, 2010a)
From page 41...
... As with agricultural practices, limited information exists to reliably document the performance and long-term cost-effectiveness of urban BMPs, particularly at a watershed scale. Activities to Control Atmospheric Pollution The atmosphere is a significant source of nitrogen to the Bay and its watershed because of the deposition of oxidized reactive nitrogen (NOy)
From page 42...
... . water quality and living resources and annually reports them in the Bay Barometer (CBP, 2009a, 2010a)
From page 43...
... 43 INTRODUCTION FIGURE 1-10 Nitrate ion wet Figure 1-10.eps 2009. deposition, 1994 and SOURCE: National Atmospheric Deposition Program/National Trend Network.
From page 44...
... 44 NUTRIENT AND SEDIMENT REDUCTION GOALS IN THE CHESAPEAKE BAY FIGURE 1-11 Ammonium ion wet deposition, 1994 and 2009. SOURCE: National Atmospheric Deposition Program/National Trend Network.
From page 45...
... suggest that much of the increase in nitrogen results from increasing nitrate and nitrite in groundwater. Average nutrient and sediment loads to the Chesapeake Bay from the Phase 5.3 Watershed Model (Figure 1-13a,b,c; Appendix A)
From page 46...
... b) Estimated concentration of dissolved nitrate plus nitrite on April 1 of each year in the Choptank River near Greensboro, Maryland, evaluated for discharge values of 53 cfs (1.5 m3/sec; solid line)
From page 47...
... An estimated 26 percent of tidal waters met or exceeded guidelines for water clarity, a 12 percentage point increase from 2008. Finally, underwater grasses covered 9,000 more acres (3,600 ha)
From page 48...
... Strategy TMDL E3 12000 NTWDep Forest 10000 Total Sediment (M lbs/year) Septic Point Source Urban runoff 8000 Agriculture 6000 4000 2000 0 1985 2009 Trib.
From page 49...
... The scenarios include 1985 baseline conditions, 2009 progress, the tributary strategy (TS) goals based on the cap loads set in 2003, total maximum daily load (TMDL)
From page 50...
... The overall TMDL nutrient and sediment reduction goals reflect relatively small modifications to the cap load goals set in 2003 (EPA, 2003)
From page 51...
... , the Caloosahatchee Estuary in Florida (23 percent reduction in total nitrogen loading; Bailey et al., 2009) and Newport Bay in California (50 percent reduction from current nutrient and sediment loadings; EPA, 2002)
From page 52...
... . If all proposed actions are implemented, the first milestone actions are anticipated to ultimately provide about 21 percent of the nitrogen load reduction and 22 percent of the phosphorus load reduction needed to meet the Tributary Strategy cap loads (Table 1-5)
From page 53...
... Milestone Nitrogen 258.5 183.1 75.4 15.8 21.0 Phosphorus 17.8 12.8 5.0 1.1 22.1 Sediment 9,500 8,293 1,207 NA NA NOTES: All load estimates, including the Tributary Strategy cap loads, were developed based on Phase 4.3 of the Chesapeake Bay Watershed Model.
From page 54...
... necessary to meet water quality criteria. The ultimate goal is to meet the ecological endpoints associated with a fully restored Bay (extent of underwater grasses, fisheries abundance, and diver
From page 55...
... . STATEMENT OF COMMITTEE TASK AND REPORT OVERVIEW In 2009, the NRC's Committee on the Evaluation of Chesapeake Bay Program Implementation for Nutrient Reduction to Improve Water Quality was formed to undertake an evaluation of the CBP's nutrient reduction program and to respond to the GAO (2005)
From page 56...
... . Figure 1-14.eps bitmap Restoration of underwater grasses, fisheries, benthic communities, and Ecological faunal diversity Endpoints Meet Bay water quality criteria for dissolved oxygen, clarity, and chlorophyll-a concentrations; 60 percent of Bay segments attaining Water standards by 2025.
From page 57...
... Evaluation Theme II: Milestones 4. Is the two-year milestone strategy, and its level of implementation, likely to result in achieving the CBP nutrient and sediment reduction goals for this milestone period?
From page 58...
... , and identifies the challenges to and opportunities for using adaptive management to meet nutrient and sediment reduction goals. • In Chapter 5, the committee describes overarching issues affecting achievement of the nutrient reduction goals (Task 6)


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