Managing the Columbia River Instream Flows, Water Withdrawals, and Salmon Survival (2004) / Chapter Skim
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3 Hydrology and Water Management
3 Hydrology and Water Management
Pages 42-70
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From page 42... ...
A vast number of jurisdictions and individuals use Columbia River water, including seven U.S. states, the Canadian province of British Columbia, and several Indian reservations (Figure 3-1)
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From page 43... ...
These structures and uses have affected stream flows, water quality, and water temperature. This chapter exam ines twentieth-century changes in Columbia basin hydrology and the annual hydrograph, the current and prospective future picture of water withdrawals (this study's primary focus)
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From page 44... ...
44 Managing the Columbia River FIGURE 3-1 Columbia River basin and federal and non-federal dams.
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From page 46... ...
. Support for federal dams on the mid-Columbia faded during the 1950s, but licenses were issued to county public utility districts to construct Priest Rapids Dam, Rocky Reach Dam, Wanapum Dam, and Wells Dam, all of which today are operated by public utility districts.
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From page 47... ...
In addition to the smoothing of the annual Columbia River hydrograph, construction and operations of the dam and reservoir system have had two other major physi cal impacts: water velocities have decreased (which has signifi cantly increased the amount of time required for juvenile salmon to travel downstream and into the sea) , and the size and orienta tion of the Columbia River plume (a zone of fresh water extend FIGURE 3-2 Distribution of monthly flows at The Dalles by 10-year blocks.
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From page 48... ...
are moving downstream. These changes, how ever, have not eliminated all variability of Columbia River flows.
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From page 49... ...
"Flow targets" were devel oped by federal and state resources agencies in efforts to ensure adequate instream flows. Key flow targets involving fishery re sources include consideration of smolt migration, spawning flows for chum salmon below Bonneville Dam, spawning and incubation flows at Vernita Bar (see Box 3-1)
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From page 50... ...
. Grant County Public Utility District is to operate the Priest Rapids Project to the extent feasible to yield river flows during daylight equal to 68 percent of daily mean inflow to Wanapum pool.
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From page 51... ...
As this report went to press, an expanded Vernita Bar Agreement was being drafted. The new agreement, tentatively called the "Hanford Reach Fall Chinook Protection Program," is to be submitted to the Federal Energy Regulatory Commission for consideration in the relicensing process.
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From page 52... ...
The total maximum withdrawal volume of these permits is 4,240,000 acre-feet per year. Withdrawal permits held by the Columbia Basin Project total 3,160,000 acre-feet per year, which represents 74 percent (by volume)
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From page 53... ...
Columns 5-7 -- Withdrawals as percentages of monthly Columbia River discharge values at John Day Dam. SOURCE: USGS, 1996; Washington Department of Ecology, 2003.
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From page 54... ...
Consumptive use at the Columbia Basin Project is about 70 percent of the volume of surface water withdrawals (Montgom ery Water Group, 1997; see also Appendix C)
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From page 55... ...
. Irrigation return flows from the Columbia Basin Project are discharged into the Columbia River through wasteways, creeks, and groundwater seepage.
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From page 56... ...
. Expansion of irrigated agriculture on Columbia Basin Project lands would increase withdrawals toward this permitted maximum, which would reduce downstream flows (although roughly 30 percent of the additional withdrawals would return to the Columbia River, a figure that could decrease over time with more efficient irrigation systems)
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From page 57... ...
. As mentioned, the Columbia Basin Project cur rently accounts for roughly 74 percent of total water withdrawals from the middle reach of the Columbia River in the State of Washington.
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From page 58... ...
border to Bonneville Dam would constitute roughly a 28 percent increase in the volume of water permits that have been issued by the State of Washington for surface water with drawals from the Columbia River and groundwater withdrawals from within 1 mile of the river (current permitted total maximum volume is 4,240,000 acre-feet per year)
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From page 59... ...
. Under minimum July flow conditions, the upper end of the proposed range of diversions would increase July withdrawals from roughly 16.6 percent of Columbia River minimum flows to roughly 21 percent of Co lumbia River flows at John Day Dam.
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From page 60... ...
RETURN FLOWS AND WATER QUALITY In addition to water withdrawals, return flows from irrigation projects like the Columbia Basin Project add to river flows and have implications for Columbia River system water quality and quantity as well as for salmon survival. Complete accounting of surface and subsurface discharges of irrigation return flows from the Columbia Basin Project is not possible because they are not measured.
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From page 61... ...
Numerous water quality parameters can FIGURE 3-7 Water temperatures (bold) in Crab Creek (which conveys return flows from the Columbia Basin Project)
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From page 62... ...
In the Columbia Basin Project, however, the conversion of surface furrow irrigation to pressurized irrigation (center pivot and sprinkler) since the 1970s (Montgomery Water Group, 1997)
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From page 63... ...
. Figure 3-8 shows maximum and average Co lumbia River August water temperatures at Bonneville Dam.
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From page 64... ...
. More importantly, it means that Columbia River water temperatures are approaching the up per limits of thermal tolerance for cold water fishes (~20° to 24°C; Mohseni et al., 2003)
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From page 65... ...
Climate variability and changes also have important implications for Columbia River water temperatures (as shown in Figure 3-8)
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From page 66... ...
Not all scientists agree that recent warming across the basin necessarily portends a warmer future, however, as some climate scientists argue that broad trends in temperature and snow accumulation across the basin are due to natural mul tidecadal oscillations in climate patters. Many atmospheric scientists are concerned that twentieth century climate warming in the Columbia River basin was a re sult of global increases in "greenhouse gases" such as carbon di oxide, and there are some concerns that warming will continue
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From page 67... ...
For example, future Pacific Northwest climate change scenarios from the Intergovernmental Panel on Climate Change and other groups and scientists (Table 3-3) suggest that air temperatures across the region are likely to increase, with less agreement on possible changes in precipitation.
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From page 68... ...
Such long-term temperature increases would represent an increased risk to the survival of Columbia River salmonids, as increasing temperature would represent a threat in terms of further increases in Columbia River water tem peratures (which also increased during the latter twentieth cen tury) and reduced flows during low-flow periods.
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From page 69... ...
. By far the largest irrigator is the fed eral Columbia Basin Project, which diverts an impressive 74 percent of total irrigation water withdrawals from the Columbia River in Washington.
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From page 70... ...
A key issue in considering the implications of prospective additional water diversions clearly is the seasonality of those di versions. Other important changes to the river include deteriorating water quality, which has implications for Columbia River salmon, and increasing water temperatures.
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