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For Fish, River Operators Alter Flood Control Operations by Mike O'Bryant Columbia Basin Bulletin - March 1, 2002

Fisheries managers chose this week to alter April flood control operations in the Columbia River Basin to benefit juvenile salmon migrants. The decision increases river flow in the lower Snake River in April but it removes the same amount of water from flows at Priest Rapids Dam during a time when chinook fry are beginning to emerge throughout Hanford Reach.

At the same time, funding for a complete system flood control study by the U.S. Army Corps of Engineers has been cut from President Bush's proposed federal budget. If funding does comes through, the study would take a formal look at the entire Columbia River Basin flood control plan to determine how the region can increase the amount of water flowing into the lower river during the spring freshet.

Until that study can be completed, the Corps is looking at modifications that can be made mid-season to flood control operations. The Corps' Greg Bauer presented such a plan to the Technical Management Team Wednesday, Feb. 26, as one option that could be used to increase water flow out of Dworshak Dam on the North Fork of the Clearwater River. It involves transferring more of the flood control protection responsibility designed for the lower Columbia River away from Dworshak Dam to Grand Coulee Dam. But, there are tradeoffs with the plan.

"We would be taking roughly (5,000 cubic feet per second) at Priest Rapids (Dam) and moving it to the Snake River," said Scott Bettin of the Bonneville Power Administration. He said that leaves lower water levels at Hanford Reach, which could make it more difficult to avoid stranding of emerging chinook fry. "There are tradeoffs we have to consider."

Normally at this time of year, the Corps and the Bureau of Reclamation draft water from storage reservoirs in anticipation of snow melt and spring runoff. Dworshak Reservoir is drafted to an elevation of 1,488 feet, an operation that provides local flood control protection as well as flood protection for property in the lower reaches of the Columbia River system. The Corps' plan leaves more water in the reservoir by drafting it only to an elevation of 1,512.3 feet by March 31. That would still provide local flood control protection, but it also stores an additional 277,000 acre feet of water that can be used to increase flows into the lower Snake River by 4.5 kcfs.

However, in order to provide the lower Columbia River with the required amount of flood control protection, BOR must draft Grand Coulee Dam by an equal amount of water. That would draft Roosevelt Lake below normal flood control operations of 1,275.5 feet to an elevation of 1,271.7 feet on March 31.

Without the shift in water storage, flows through Lower Granite Dam in April would be about 60 kcfs, but flows increase with the shift to 64.5 kcfs. On the other hand, flows at Priest Rapids will drop about 4.5 kcfs. TMT did not discuss how the lower flow at Priest Rapids Dam through April could affect Grant County Public Utility District's stranding operations, which are expected to begin in March.

The reservoirs return to normal operations by April 30. Although a chunk of water -- 277 kaf -- is transferred from the mid-Columbia River to the lower Snake River, the Corps and BOR are able to bring both reservoirs back to normal flood control levels by that date.

Bauer warned that a dramatically lower March water supply forecast would change the analysis and TMT would have to revisit its decision.

TMT is attempting this year to inform their decisions on issues such as transferring water from one section of the basin to another by using additional tools. One of those tools that the Corps began using last year is Q-Adjust. In the latest analysis, the Corps took the current water supply forecast and analyzed it according to each of the last 59 years of runoff in individual sub-basins. The Corps' Cindy Henriksen said the outcome is 59 different flow shapes, which is information the Corps and now TMT can use to estimate flows and make refill predictions for reservoirs.

For example, given the current known water supply forecast, Q-Adjust found that April through June flow objectives at Priest Rapids Dam of 135 kcfs were met in early April in 10 of those years, with an average flow of 112 kcfs. That rises to 30 years in late April (141 kcfs average flow), 57 years in May (154 kcfs average flow) and 54 years in June (170 kcfs average flow). The analysis also found that Grand Coulee Dam completed refill in 59 of those years by June 30 and Dworshak in 36 of those years. The Corps has done similar analyses for other sub-basins.

Another tool is NMFS' analysis contained in its BiOp of risk and improvement in survival needed to achieve recovery of various fish stocks listed as threatened and endangered under the federal Endangered Species Act. Although it is difficult to quantify the impacts of individual actions, according to Chris Tooele of NMFS, some actions are still consistent with biological principles, "even if we don't know the final effect" of an action, said Paul Wagner, also of NMFS. Generally, those are actions that can be counted on to do some good.

Still, the BiOp does provide a way of identifying the stocks at risk in each subbasin. For example in the case of the change in flood control operations approved by TMT this week, "we're helping spring chinook in the Snake River that are worse off than those in the Columbia River," said Jim Litchfield, representing Montana.

Much of this piecemeal approach to altering flood control operations could change in the future after a Corps study, according to Tim Kuhn, Corps program manager. Kuhn said the Corps completed an initial appraisal of its system flood control study that surveys the background issues relating to basin flood control, but that funding for the next step is not included in the Administration's 2003 budget, even though the Corps asked for the $300,000. That study, known as the reconnaissance level study, would narrow down the options, identify the full scope of the final study and take about one and one half years, he said. That is the second of three studies it will need to comply with a requirement in the National Marine Fisheries Service 2000 Biological Opinion.

"We're stuck in the water as far as doing any work," Kuhn said. He also said that if non-federal interests showed support for the study, it could still make the President's budget. He is also looking for non-federal sponsors, such as states, to cost-share about 50 percent of the $10 million feasibility study, the final of the three studies needed. The BiOp calls for the Corps to complete that study in 2005, but Kuhn said that will not be possible.

"That is not going to happen, even if we start in 2003," Kuhn said. "But, we need to get going."

Related Sites:
Technical Management Team