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Options Discussed In Maintaining Flows For Chum Redds With Below Average Upper Basin Water Supply
Posted on Friday, March 08, 2019 (PST)

With continued low flows and less than average projected water supplies in the upper Columbia River basin, the interagency Technical Management Team this week began serious talks about how much longer minimum flows can be sustained that aid threatened chum salmon redds downstream of Bonneville Dam.


Although the April through July water supply forecast for Lower Granite Dam in the Snake River basin is at 19.563 million acre feet, 99 percent of normal, upper Columbia River water supply is far lower and forecasts are less certain.

 

Grand Coulee water supply, April through August, is 48.998 MAF, just 86 percent of normal; Albeni Falls is 10.354 MAF, 84 percent of normal; and Columbia River flows will get little help from British Columbia where precipitation at Arrow Dam has been at just 58 percent of average, according to information provided by Doug Baus of the U.S. Army Corps of Engineers at this week’s TMT meeting.

 

Overall, the March water supply forecast at The Dalles Dam, which among other things sets flood control elevations at Grand Coulee, is 76.636 MAF, April to August, just 88 percent of normal (http://pweb.crohms.org/tmt/documents/WSF/WSF_WY19_03.pdf).

 

Water from Grand Coulee Dam has been augmenting flows at Bonneville Dam to maintain the tailwater elevation at the lower dam at 11.3 feet to protect incubating chum eggs. The chum are protected, listed as threatened under the federal Endangered Species Act. Also at risk are thousands of fall chinook redds that spawned in the same area (fall chinook are not listed under the ESA).

 

“The challenge is the upper Columbia,” Baus said. Conditions are projected to have below average precipitation and below average temperatures, he added, looking at forecasted weather predictions. “But, we’re not getting enough of it.”

 

However, the reservoir level is projected to be far below the Corps’ upper flood control rule curve (an elevation of somewhere around 1,245 to 1260 feet) by April 10, which could have an impact on the spring flows, and that has the Bureau of Reclamation worried that flow augmentation for future fish flows would be at risk during the summer.

 

“The Bureau of Reclamation's position is that April 10th is a priority as defined in the FCRPS Biological Opinions and the Water Management Plan,” said Joel Fenolio of the BOR. “The last time we abandoned chum was in 2013 and we’re now nine feet lower. We can’t keep kicking the can down the road.”

 

The upper flood control curve is a provision in the Columbia River power system biological opinion. Its objective is to have the federal storage dams be as full as the flood control rule curve allows so that the spring runoff will go to the river instead of filling empty reservoir space.

 

Much of the issue that has fisheries managers at TMT so concerned is that there is a lot of low level snow in the region and it is difficult to know how much that snow will contribute to the water supply or even when that and higher elevation snow would begin to melt.

 

“Low elevation snow is tough to call,” said Charles Morrill of the Washington Department of Fish and Wildlife. “I favor going week to week,” he said of making the decision about changing chum flows.

 

“There is snow on the ground from here to Spokane,” Paul Wagner of NOAA Fisheries said at the March 6 meeting. He added that the weather forecast could change, causing the snow to melt and forcing the BOR to instead draft Coulee. If that happened, “we would already have abandoned chum, but it would have been a bad decision.”

 

The chum arrived early this year and chum operations to protect the fish and their redds (nests) began Nov. 2, about a week earlier than normal. Operations for the chum go on for about five months into April, but generally transitions in late-December from spawning to chum incubation flows.

 

When protecting spawning salmon, chum operations ensure that enough water will flow over chum redds to protect the redds and fertilized eggs until they emerge in spring. Initial spawning operations seek flows high enough to protect chum as they build their redds, but not so high that chum would have been encouraged to spawn in areas that could be dewatered when flows drop.

 

Spawning operations maintain the dam’s tailwater elevation at a minimum 11.3 feet so that the fish can move into spawning areas near Hamilton Creek and Ives Island. However, fluctuations to higher tailwater elevations is limited to 13 feet.

 

For incubation, the tailwater elevation is set simply to keep water over the redds through incubation.

 

Flows at Bonneville are currently at about 173,000 cubic feet per second (March 7) and that is expected to drop to about 133 kcfs by March 9 and to about 120 kcfs through mid-month (see NOAA’s River Forecast Center at https://www.nwrfc.noaa.gov/river/station/flowplot/flowplot.cgi?id=BONO3).


TMT will meet Monday, March 11, to debate the future of chum operations at Bonneville.

 

Also see:

 

-- CBB, January 11, 2019, “ESA-Listed Chum Salmon Operations Transition From Spawning Flows To Protecting Egg Incubation,” http://www.cbbulletin.com/441992.aspx

 

--CBB, December 14, 2018, “Flows Managed To Aid ESA-Listed Chum Salmon Continuing To Arrive Below Bonneville Dam,” http://www.cbbulletin.com/441914.aspx

 

-- CBB, November 2, 2018, “ESA-Listed Chum Salmon Arrive Early Below Bonneville Dam; Flow Operations Begin To Protect Spawning,” http://www.cbbulletin.com/441754.aspx

 

--CBB, January 19, 2018, “Agencies Identify Spawning Areas For Chum, Confirm Safe Water Levels Over Redds,” http://www.cbbulletin.com/440103.aspx

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