Managing the Columbia River: Instream Flows, Water Withdrawals, and Salmon Survival (2004)

The Columbia River basin is a vast hydrological system subject to large and often unpredictable physical, biological, and human-induced changes. Despite the construction and operations of the Federal Columbia River Hydropower System, the river’s flows still vary on many different timescales and often in ways that are not fully predictable. In addition, prospective future changes in climate are likely to affect seasonality of flows as well as water temperature. Additional diversions from existing projects and users, as well as additional demands from human population growth (currently increasing and highly likely to continue), are likely to diminish streamflows.

Columbia River salmon populations have been affected by a variety of human activities and have declined over the past century. The declines have been steady but have also exhibited considerable variability, with occasional years of low returns and occasional years of abundant returns, such as those witnessed in the early 2000s. The long-term decline of salmon populations, especially wild fishes, however, is undeniable. Documented increases in Columbia River water temperature are approaching, or have exceeded, thresholds of physiological importance to many salmonid stocks. Migratory behavior and survival rates of salmon are also affected by low river flows. This situation is especially troubling because of prospective future climate warming (which could entail not only higher water temperatures but also further decreases in low flows) and demands for additional diversions of Columbia River water during low-flow periods. Further increases in water temperature and further reductions in low flows would exacerbate risks to salmon survival. As this report has noted, the effects of prospective additional withdrawals in July (234,000 acre-feet) could be substantial. July is a period of high demand for Columbia River water. The upper end of the range of prospective additional withdrawals considered in this

study would increase July withdrawals from their current value of roughly 6.8 percent of mean Columbia River flows to roughly 8.6 percent. Under minimum July flow conditions, the effects would be greater: the upper end of the proposed range of diversions would increase current July withdrawals from roughly 16.6 to 21 percent of Columbia River minimum flows.

The seasonality of Columbia River flows and changing demand patterns for additional water from various users in different parts of the river basin suggest that sound water management decisions require a comprehensive basinwide water management scheme. Ideally, the management framework would have the flexibility to respond to the seasonality of Columbia River flows and have the flexibility to responsibly transfer water from lower-value to higher-value uses. Increased flexibility in managing the Columbia River will require greater emphasis on nontraditional approaches to augmenting water supplies, such as water marketing and water transfers, and greater cooperation of political entities across the basin. These market-based programs may require capital investments in physical infrastructure and human resources investments in experts with skills in fields such as finances, marketing, and public administration. Programs such as water transfers, groundwater banking, and other measures to increase the efficiency of water use hold promise in helping sustain the regional economy in ways that do not require ever-increasing water withdrawals. Although water uses across the basin should not be simply channeled to the highest bidders for water, such measures hold promise for helping support both economic and environmental goals and should be carefully considered.

A key problem in managing the basin’s water is that water permitting decisions are currently made in a piecemeal fashion, with little to no consideration of their effects on other users or their degree of consistency with other decisions across the basin. If water resources and risks to salmon survival are to be better managed, Columbia River water permitting decisions must be made in a more holistic fashion, with consideration of how additional diversions would affect other users and sectors across the entire river basin. A joint forum composed of Columbia River basin entities would allow for more accurate inventorying, monitoring, and enforcement of existing water rights. There is also a need for stronger efforts toward water conservation and market-based management strategies, which could help reduce present

tensions related to competition over water supplies. Many of these types of nontraditional means for augmenting water supplies have been applied to good effect in some water-short areas of the West. Their prospective applications in the Columbia River basin should be carefully explored.

Water withdrawal applications and permitting decisions are highly contentious in both the State of Washington and other parts of the Columbia River basin. Inflexibilities in traditional western U.S. prior appropriation doctrine have contributed to these tensions. A greater degree of flexibility in traditional water permitting and rights processes is paramount to better water management and to decreasing tensions and conflicts in the basin. This report recommends implementation of a joint basinwide water management forum and the pursuit of nontraditional water marketing and conservation strategies. A water permitting and rights process that more explicitly recognizes seasonality of flows should also be devised. Decisions regarding the granting of new water rights are issues of public policy, but additional water withdrawals during the critical high demand and low-flow periods discussed in this report will increase the risks of survival to listed salmon stocks. It will also decrease the flexibility of management institutions to allocate water between different uses in critical low-flow conditions. To increase the flexibility of water management organizations and programs and to better recognize uncertainties regarding future supplies and demands, a permitting process should be created that allows for withdrawals to be discontinued during periods of low flow and periods of comparatively high water temperature.

To reiterate and reinforce this report’s six key findings and recommendations, they are repeated here:

• Within the body of scientific literature reviewed as part of this study, the relative importance of various environmental variables on smolt survival is not clearly established. When river flows become critically low or water temperatures excessively high, however, pronounced changes in salmon migratory behavior and lower survival rates are expected. (Chapter 4).

• The State of Washington and other Columbia River basin entities should continue to explore prospects for water transfers and other market-based programs as alternatives

to additional withdrawals (Chapter 6).

• The conversion of water rights to uninterruptible status will decrease the flexibility of the system during critical periods of low flows and comparatively high water temperatures. Conversions to uninterruptible rights during these critical periods are not recommended (Chapter 7).

• Sound, comprehensive Columbia River salmon management strategies will depend not only on science but also on a willingness by elected and duly appointed leaders and managers to take actions in the face of uncertainties (Chapter 7).

• Decisions regarding the issue of additional water withdrawal permits are matters of public policy, but if additional permits are issued, they should include specific conditions that allow withdrawals to be discontinued during critical periods. Allowing for additional withdrawals during the critical periods of high demand, low flows, and comparatively high water temperatures identified in this report would increase the risks of survivability to listed salmon stocks and would reduce management flexibility during these periods (Chapter 7).

• The State of Washington and other basin jurisdictions should convene a joint forum for documenting and discussing the environmental and other consequences of proposed diversions that exceed a specified threshold (Chapter 7).