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River Managers Mull Operations To Expand Spawning Area For Listed Chum Below Bonneville Dam
Posted on Friday, November 11, 2011 (PST)

Fishery managers are hoping for high chum salmon numbers and high flows (precipitation plus) this late fall and winter to enable Columbia River dam operators to create an expanded spawning area for the threatened species below Bonneville Dam.


NOAA Fisheries’ Paul Wagner on Wednesday presented for consideration a “framework” that would allow, -- “if fish numbers of unspawned adult chum salmon are significant and natural precipitation results in flow levels that require a substantial increase in nighttime flow to maintain the 11.5 foot daytime tailwater” -- an increase of the tailwater elevation to 12.5 feet during the last week in November, and to 13.5 feet in December.


The system operations request was submitted Wednesday to the Technical Management Team, which mulls federal Columbia-Snake river hydro operations that might benefit fish. TMT is made up of federal, state and tribal hydro and fish managers. NOAA Fisheries is charged with protecting fish stocks, such as lower Columbia chum, that are listed under the Endangered Species Act.


Higher tailwaters would inundate additional areas on Ives Island just below the dam that have in the past been known as “very desirable habitat” for chum, Wagner said.


That would help to “reduce the risk” to chum spawning populations, Wagner said. A December shift to the 13.5 elevation should not result in great numbers of fish spawning at the higher elevation, he said. Peak redd density at Ives Island typically occurs around Dec. 1 with a lesser number of spawners arriving after that date.


“Higher tailwater through Bonneville will potentially increase the amount of spawning habitat and change the locations of suitable redds, and may provide additional returns to this area,” according to the SOR, which was signed by NOAA Fisheries, the U.S. Fish and Wildlife Service, the Oregon and Washington departments of fish and wildlife, the Shoshone-Bannock Tribes and the Columbia River Inter-Tribal Fish Commission.


Russ Kiefer, who represents the state of Idaho at TMT, said his state supports the request but chose not to weigh in officially as a signatory because Idaho is not involved in chum management. The Columbia River chum populations are for the most part confined to areas downstream of Bonneville, which is located at river mile 146. Idaho bound salmon and steelhead must swim 400 miles and more up the Columbia and Snake rivers to reach their destination.


Chum seek spawning areas that have upwellings of spring water that are, generally, somewhat warmer that the surface water.


Higher tailwater elevations would then, ideally, be maintained into April when juvenile chum emerge from the gravels. Maintaining higher elevations can, depending on the available water supply, reduce the flexibility of Bonneville and dams upstream to be operated for power production and other fish needs.


The Ives Island area is the target of the only hydro system operational prescription outlined in NOAA Fisheries’ 2008 Federal Columbia River Power System specifically to benefit chum salmon. It calls for the maintenance of a tailwater elevation below Bonneville Dam of approximately 11.5 feet beginning the first week of November (or when chum arrive) and ending by Dec. 31, in the area of the Ives Island complex and/or access to the Hamilton and Hardy creeks, which feed into the Columbia in the Ives-Pierce island area, for the spawning population. The goal in recent years has been to keep the tailwater in the 11.3-11.7-foot range.


Thereafter TMT is charged with guiding operations, when possible, that assure egg-filled chum redds remain underwater. That involves calling on the resources of the system’s two main storage reservoirs, Lake Roosevelt behind Grand Coulee Dam on the mid-Columbia in central Washington and Lake Pend Oreille behind Albeni Falls Dam on the Pend Oreille River in the northern Idaho Panhandle. The Pend Oreille is a tributary to the Columbia.


A primary limiting factor for chum operations is another BiOp goal -- achieving a Lake Roosevelt elevation on April 10 that represents the maximum amount of water storage allowed within flood control constraints. Operators want to assure there is enough space in the reservoir to protect against downstream flooding, while holding as much water as possible for use later in the spring and summer to augment flows for other salmon and steelhead stocks that are migrating toward the ocean.


No decision was made Wednesday regarding the SOR, which offers an off ramp if weekly updates long-range forecasts of water supply take a turn for the worse.


“If these forecasts indicate that the 85 percent probability of reaching the April 10 refill objective [at Grand Coulee] is at significant risk, the tailwater elevation would be lowered to an appropriate level,” the SOR says.


“Some additional risk [to the refill objective] exists by placing redds at the higher elevations, but the numbers of redds expected to be formed at these higher elevations will be low, which will reduce the downside risk to the population if they cannot be maintained through emergence,” the SOR says.


The raising of the tailwater elevation would depend on whether wet weather, and wet forecasts, materialize.


“If not, we would likely abandon the higher elevation redds, should they exist,” Wagner said.


“The recent completion of additional spawning habitat in the Hamilton spring channel site should further reduce the risk to chum salmon spawning in the Ives Island area,” the SOR said restoration work that has taken place over the past year in the nearby Hamilton spring area.”


Another goal of the proposed expansion of accessible habitat is to reduce the incidence of superimposition of spawners, i.e. redds being built on top of redds.


The SOR argues that raising the tailwater elevation to increase the habitat area is worth a try, since Ives Island spawning populations have been in decline since 2002, which was a high-water mark, in terms of estimated spawning populations, at most lower Columbia sites since officials began considering chum for listing. The chum listed in 1999.


The Bureau of Reclamation’s John Roache said his agency would not object to such an operation, as long as it was sure it could still carry out planned operations of Grand Coulee. Likewise it is important to the Bureau that it be able to fill Banks Lake near Lake Roosevelt. Banks is used for irrigation during the summer months. And the agency must have the ability to help satisfy the Vernita Bar agreement, which outlines operations needed to protect fall chinook redds and juveniles in the Columbia’s Hanford Reach.


“We need to look at all of that stuff” before implementing such an operation, Roache said.


Likewise Sherry Sears of the Confederated Tribes of the Colville Reservation said the tribes would not support a Lake Roosevelt drawdown to accomplish the SOR.


“We don’t want to jeopardize our resources to water an additional 100 redds,” she said. The tribes are involved in the management of chinook salmon and other species that call the mid and upper Columbia home.


The Bonneville Power Administration’s Tony Norris was skeptical about stepping up the Bonneville tailwater elevation based on a few early-season rain events and forecasts.


“13.5 feet is a lot of water. I hope we don’t go there. You may only be affecting a very few fish,” Norris said. “It doesn’t add up for us.” BPA markets power generated in the federal Columbia-Snake hydro system.


The overall chum spawning estimate 2002 for areas from Interstate 205 and Portland up to Bonneville was 11,351. But annual estimates have been generally been in decline since then. The 2010 preliminary estimate is for a total spawning population of 3,509, which was actually more than double the 2009 total. But estimates from 2005-2008 were 2,000 or less.


The Ives area spawning population estimated was 4,466 in 2002, according to data provided to TMT by Cindy LeFleur of the Washington Department of Fish and Wildlife. That total dropped to less than 2,000 in 2003, then fell off the table. Estimates from 2004 through 2010 have been less than 400. The preliminary 2010 total was 214.


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