Breaching the four lower Snake River dams and increasing spill at the four lower Columbia River dams would provide the largest benefits for several ESA-listed salmon, but would also result in unacceptably high adverse impacts to hydropower, navigation, irrigation and existing recreation.
That's one of many conclusions in the Columbia River System Operations Draft Environmental Impact Statement released Feb. 28, marking the start of a 45-day comment period that closes April 13.
The Preferred Alternative option in the draft EIS would keep the four lower Snake River dams in place, and calls for increasing spring spill to a point that would lower hydropower production by 160 aMW in an average water year and by 300 aMW in low water years, while increasing juvenile fish survival through the system.
Developed by the U.S. Army Corps of Engineers, Bureau of Reclamation and BPA, the draft EIS evaluates six alternatives, including a No Action alternative, for operating and maintaining 14 federal hydropower projects on the Columbia and Snake rivers.
"The alternatives explore a range of spill levels to support juvenile fish passage, varying levels of hydropower generation by seasonal changes in flows, and differing actions to support the needs of Endangered Species Act (ESA)-listed anadromous and resident fish," the document's executive summary states.
Five "multiple objective" alternatives seek to address one or more of eight objectives for operating the system. Using analyses from four of the alternatives, the agencies developed a fifth preferred alternative, described as a "suite of operational and structural measures" that would meet the many needs and purposes of the dams.
Objectives of the EIS are to improve juvenile salmon survival, improve adult salmon survival, improve resident fish survival, provide a reliable and economic power supply, minimize greenhouse gas emissions, maximize adaptable water management, provide water supply and improve conditions for lamprey.
The draft EIS was released after more than three years of work, including regional collaboration between the three agencies and more than 30 tribal, state, federal and county agencies.
"We could not have reached this important milestone without the expertise and input of the many cooperating agencies that have participated in this process," BPA Administrator Elliot Mainzer said in a statement. "This was truly a regional effort, and we are especially grateful to our tribal partners for providing their perspectives and expertise on the Columbia River System."
Much attention has been given to one of the alternatives—Multiple Objective 3—that evaluated breaching Lower Granite, Little Goose, Lower Monumental and Ice Harbor dams, and proposes a spring spill that reaches 120 percent total dissolved gas in the tailraces at McNary, John Day, The Dalles and Bonneville dams. The analysis was required by a court order in National Wildlife Federation et al. v. National Marine Fisheries Service et al.
"MO3 would only partially meet the Purpose and Need and some of the objectives for the EIS to various levels," the summary states. "Additionally, breaching the dams would not allow co-lead agencies to operate and maintain the dams for their congressionally authorized purposes of navigation, hydropower, envisioned recreational benefits, and water supply for irrigation purposes. It also has the highest adverse impacts to other resources, especially social and economic effects. However, it predicts the highest benefits for several of the ESA-listed juvenile adult salmon," it says.
Breaching the dams would meet objectives for improved survival for juvenile salmon, adult salmon, resident fish and lamprey, the summary states. It uses both a NOAA Fisheries' Life Cycle Model, which includes COMPASS, and a Fish Passage Center model called Cumulative Survival Study to evaluate the benefits to fish. Both models "showed the highest predicted potential smolt-to-adult returns (SARs) for Snake River salmon and steelhead among the alternatives," and little change compared to no action for fish outside the Snake River, it says. The CSS model predicts SARs to Lower Granite Dam would increase by 170 percent, while the LCM model predicts a 14 percent improvement relative to taking no action.
But the dam breaching alternative would not meet objectives for providing a reliable and economic power supply. "Under MO3, hydropower generation would decrease by 1,100 aMW under average water conditions, and 730 aMW under low water conditions compared to the No Action Alternative," the summary states. This alternative would more than double the region's risk of power shortages—from a 6.6 percent risk of having a year with power shortages under No Action—or roughly one year of power shortages in 15 years—to a 13.9 percent chance of having a power shortage year—or one year of power shortages in seven years, the summary states. It notes that significant quantities of replacement resources would be needed to maintain reliable power, and analyzed two potential replacement portfolios.
Under the least-cost portfolio, new resources would include 1,120 MW of combined-cycle natural gas-fired turbines costing about $200 million a year, which would increase Bonneville's wholesale rate pressure by between 8.2 and 9.6 percent. "If Bonneville had to replace the lower Snake River projects' full capacity with zero-carbon resources, the rate pressure could be up to 50 percent on wholesale power rates," it says.
Breaching the dams would also not meet objectives for minimizing greenhouse gas emissions, and, under the low-cost replacement portfolio, would lead to an additional 3.3 million metric tons of CO2—a 10 percent increase in power-related emissions across the Northwest, the draft EIS says.
The alternative would also result in major adverse impacts to irrigation in the lower Snake River, with a lost social welfare benefit of $458 million. It would also cause major adverse impacts to transportation, with an average increase in transportation costs of 10 to 33 percent, it says.
The document notes that new congressional authority and funding would be required to breach the dams.
Other multiple objective alternatives analyzed include MO1, which prioritizes benefits to lamprey and ESA-listed fish through a block spill design for juvenile fish; MO2, which prioritizes hydropower production and flexibility and reduction of regional GHG emissions, benefiting ESA-listed salmon through structural measures and increased transport for salmon; and MO4, designed to help ESA-listed fish by increasing spill to 125 percent TDG.
The draft EIS also identifies and analyzes a Preferred Alternative that seeks to meet all the EIS objectives and balance the needs of the dams' authorized purposes.
"After evaluating the potential effects of the alternatives on the environmental, social, and economic resources, the ability to meet objectives and fulfill the Purpose and Need Statement, and effects to flood risk management, water supply, hydropower generation, navigation, fish and wildlife conservation, cultural resources, recreation and other purposes, the co-lead agencies developed a Preferred Alternative designed to achieve a reasonable balance of competing river resource needs and co-lead agency mission requirements," the executive summary states.
To create the Preferred Alternative, the agencies modified fish spill operations using the analysis from the range of spill levels evaluated in the other multiple objective alternatives.
"The intent was to create an opportunity for a major potential benefit to salmon and steelhead through increased spill, as indicated by the CSS model, while avoiding many of the adverse effects to power generation and reliability associated with juvenile spill operations analyzed in MO4 [the high-spill alternative]," it says. This alternative acknowledges the range of potential outcomes predicted by the different models, and includes a study to evaluate the potential benefits and unintended consequences of significantly higher spill.
According to the executive summary, the Preferred Alternative meets objectives for improving survival for juvenile salmon, adult salmon, lamprey and resident fish. The CSS model predicts a 35 percent improvement in SARs for Snake River Chinook, and 28 percent improved SARs for Snake River steelhead, it says. The alternative also addresses adult migration delays caused by high spills through testing and evaluation, and includes modifications at John Day Reservoir to disrupt Caspian terns, which eat juvenile salmon and steelhead.
The Preferred Alternative also would meet objectives for providing a reliable and economic power supply, although it would decrease hydropower generation by 160 aMW in an average water year, and by 300 aMW in a low water year, due to the increased spring spill for juvenile passage.
"While overall hydropower generation would decrease under the Preferred Alternative, reliability is comparable to that of the No Action Alternative because other measures increase hydropower generation slightly in the winter, and more substantially in late August, and increase hydropower flexibility in some locations and periods," it says.
The alternative places additional rate pressure of 2.7 percent on Bonneville's wholesale power rates relative to No Action, it says, although additional rate sensitivities could lower the rate pressure to 0.4 percent. The rate pressure is within a range that may be offset by cost reductions, the summary says.
The alternative "marginally meets" the objective for minimizing GHG emissions. "Due to the reduction in hydropower generation, air quality would most likely be degraded slightly and greenhouse gas emissions in the Northwest would likely increase by an estimated 0.26 MMT (or 0.70 percent) compared to the No Action Alternative," it says.
The alternative also meets objectives to maximize adaptable water management and provide water supply.
Agencies expect to issue a Record of Decision with final recommended actions in September.
NW Fishletter will cover regional responses to the draft EIS in next month's issue.