the film forum library tutorial contact

Workshop Looks at New Ways to Handle Flood Control by CBB Staff Columbia Basin Bulletin - February 13, 2004

Columbia Basin federal dam operators could keep as much as 8 million acre feet (maf) more water in reservoirs in the winter to be used to augment flows in the spring and have more than 3 maf more to augment summer flows to aid salmon in low water years if they changed early-year flood control operations, according to calculations by the Columbia River Inter-Tribal Fish Commission.

The idea is to keep more water in upriver storage reservoirs during the winter and early spring in low water years and then to use the water later when salmon need it the most.

Dam operators now draw reservoirs down by April 10 to make space in the reservoirs in anticipation of the spring runoff. That date wouldn't change, according to the CRITFC recommendation, but how far the reservoirs are drawn down would change and so would the date the reservoirs would refill.

The idea was pushed this week at a regional flood control workshop sponsored by CRITFC and attended by dam operators, climatologists and emergency management folks. This is the second flood control workshop hosted by CRITFC. The first was in 2001.

"Our mission is to use the best scientific tools available to move the Columbia River back into a normal peaking hydrograph," said Bob Heinith of CRITFC. "We see flood control as a key way to do that, but without engendering a flood risk in the major population centers."

Heinith hopes the workshop will spur thought in the region about how dam operators could change flood control regimes designed to protect property downstream from flooding while gaining precious water to return the Columbia River system to a more natural flow. CRITFC said that type of flow improves salmon survival by providing increased turbidity and habitat, shorter travel times for juvenile salmon migrants and higher river and estuary productivity.

The workshop's timing was aimed to provide the U.S. Army Corps of Engineers with information and new thinking about a study it has already begun which would consider alternatives to the way it and the Bureau of Reclamation now conduct flood control operations. The study was required in NOAA Fisheries' 2000 Biological Opinion of the Columbia River hydro system and it is now in the reconnaissance stage.

That's the stage when the Corps identifies whether there is a federal interest to do the study, said Lonnie Mettler, from the Corps' Walla Walla District. In this stage, the agency defines the problem, as well as some objectives and alternative measures that it would look at in a feasibility study, but does not yet involve analysis, modeling or new data.

If the Corps decides to proceed to the feasibility study, it would have to get congressional approval and funding, Mettler said. He doesn't expect the final study to be done until 2008.

"This is a challenge because we are looking at the entire Columbia Basin, including Canada and the relationship between the U.S. and Canada," Mettler said. "That is not a quick process."

The Corps must also decide how the multi-million dollar study could be funded.

"At the present time, because it came out of the BiOp, the funding source would be the Columbia River Fish Mitigation program," Mettler said. That's the pot of money that federal agencies use to make fish passage improvements at dams. "It will be expensive and, if it comes from the fish mitigation program, it would impact other fish activities and that may not be the best thing."

An alternative would be to get special funding from Congress or to look for a non-federal sponsor, he added. "But, I don't think there are too many people around here who would be willing to lay down several million dollars to cost share this."

Another difficulty will be getting Canada involved in the new flood control operations.

"Changes to flood control operations in Canada assumes there would be no changes to protection at The Dalles. But this study anticipates changes at The Dalles, so we would have to resolve that through the Columbia River Treaty," Mettler said. "If there is a perceived benefit to Canada, they may want to participate." However, changes to the Treaty are "glacial" and it could be expensive, he added.

Flood control protection beyond what is called for in the Columbia River Treaty is currently available, said Eric Weiss of BC Hydro, which operates three complexes of dams on the Columbia River in British Columbia. Those include Mica, Arrow and Duncan dams. However, the additional protection is prohibitively expensive because it includes the cost of BC Hydro's lost generation revenues and the United States has never asked for that protection, largely due to the cost.

The United States already has received benefits from Canadian flood control operations, Weiss said. It paid Canada $64 million or 50 percent of the estimated present value of the future prevented flood damage when the Treaty dams were completed. But that has already been paid back and more. The damage avoided in just two floods since then -- 1972 and 1974 -- amounted to about $200 million each.

Still, BC Hydro has identified another 0.5 maf of protection it could achieve by shifting storage from Arrow Dam to Mica Dam. While BC Hydro's flood control priorities through the Treaty are to minimize flooding at lower Columbia River population centers, such as Portland, it also must ensure it minimizes local flooding in Canada.

Kyle Martin, senior hydrologist at CRITFC, said that over time as dams were built in the Columbia Basin the hydrograph has changed from one with natural peaks in the spring and early summer to a fairly flat hydrograph, "like a comatose patient and that's not good for fish and wildlife."

Altered flood control could add 7.3 maf to 8 maf of extra flow to the river in late spring, he said. The CRITFC natural river plan would shift higher winter flows resulting from the Corps and Reclamation evacuating projects for flood control into the spring. In addition, it calls for refilling reservoirs by May 31, a month earlier than the current refill target of June 30, and then passing the inflow through June when much of the natural runoff occurs. It does this by reducing the amount of water drafted at these dams in February, March and early April. For example, under low flow conditions, instead of reducing water storage at Grand Coulee in March, the CRITFC plan would keep the reservoir fairly full.

The change in flood control would add more storage to the federal system of reservoirs, including 3.864 maf at Grand Coulee Dam, 1.133 maf at Dworshak Dam, 179 kaf at Brownlee (not a federal dam), 2.612 maf from Mica and Arrow dams in Canada and 250 kaf from Libby Dam. That adds up to about 8 maf extra water that could be used for salmon flows during a low water year and would provide an average June peak flow at The Dalles Dam of 338,000 cubic feet per second, and an average peak flow in a low flow year of 220 kcfs. Spring flows at McNary Dam would increase by 7 percent and by 5 percent during the summer. There is also an additional 3.3 maf of benefits that would be realized during summer months.

Generation would increase in the summer under this plan, but would decrease in the winter, Martin said, calling for the Bonneville Power Administration to tap into more non-hydro resources during the juvenile migration to ensure spill occurs.

However, such a plan would increase the risk of floods downstream from the current 14 percent to 16 percent and the bank full risk rises to 50 percent from the current 42 percent. Still, the 1996-1997 winter flood was higher than flows resulting from implementing the CRITFC proposal, which Martin said could result in additional minor flooding at best.

The Corps already is implementing this year a modified flood control plan called VARQ, which shifts some flood control operations from Libby Dam on the Kootenai River in Montana and Hungry Horse Dam Dworshak Dam on the North Fork of the Clearwater River in Idaho to Grand Coulee Dam on the Columbia River in northeast Washington. More water is left in Libby and Hungry Horse Dworshak dams, while Grand Coulee assumes more of the flood control responsibility and drafts more water.

But the difference isn't a one to one relationship, like some people think, said Pat McGrane of the Bureau of Reclamation, which owns and operates Grand Coulee Dam. In other words, less water has to be evacuated from Grand Coulee than is held back in the other two reservoirs, so there is an additional benefit.

McGrane added that Reclamation by its primary mission of providing water for irrigators, thinks more about making sure its projects are filled than it worries about flood control and, in fact, many of the Reclamation projects don't even have flood control space.

"Power and flood control work together," he said about Corps dams. "Irrigation and flood control work against each other. In dry years, we can't even fill to flood control levels" at some Reclamation projects.

Still, Reclamation's Hungry Horse Dam can also contribute to VARQ when the water supply at the dam is at 2.0 maf or less. Below that level, the dam could provide about 300,000-acre feet, McGrane said.

Carolyn Fitzgerald, from the Northwestern Division of the Corps, said that the shift at Libby Dam in 25 percent of years could potentially free up an additional 600 kaf from Libby that could be used later, but that the full 600 kaf is not beneficial in all of these years. She concluded that if the December final water supply forecast for Libby Dam is predicted to be less than 5,500 kaf, or 88 percent of normal, then relaxing flood control to gain the 600 kaf would be beneficial. However, above 5,900 kaf, or 95 percent of normal, relaxing flood control would not be beneficial. Between those poles, partial flood control is appropriate and the Corps could interpolate to determine how much flood control relaxation would be appropriate.

To be able to confidently change flood control operations without also causing the chance of floods to significantly increase would require better streamflow forecasting, something researchers at the University of Washington are developing. The accuracy is improving because of a better understanding of how global climate -- specifically the Pacific Decadal Oscillation and the El Nino Southern Oscillation -- impacts Northwest weather. This understanding is allowing climatologists to more accurately predict ahead of the winter (as early as August) what may happen. Those early forecasts are then adjusted in late November and December as more and more snow piles up in the mountains, said Alan Hamlet, of the Climate Impacts Group at the U of W.

Andrew Wood, also of the Climate Impacts Group, said the early predictions are still an evolving experiment, but that forecasting winter and spring streamflows as early as August is improving.

Overall, those who attended the workshop agreed that the Corps in its study should push for higher peak flows in low and medium flow years while providing current flood control protections in high flow years.

Related Sites:
CRITFC: www.critfc.org U.S. Army Corps of Engineers, Portland District: www.nwp.usace.army.mil
Bureau of Reclamation, Pacific Northwest Region: www.usbr.gov/pn
U of W Climate Impacts Group: www.hydro.washington.edu/Lettenmaier/Projects/fcst