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Commentaries and editorials

Idaho Water Users Stress New Paper
on Flow Augmentation

by Bill Crampton
Columbia Basin Bulletin - December 12, 2003

The Idaho Water Users Association this week forwarded to NOAA Fisheries and the Bureau of Reclamation a new scientific paper contending that flow augmentation from Idaho reservoirs provides little benefit for salmon and steelhead, and that the effects of water withdrawals on fish travel time are "small to insignificant."

The paper -- "Toward a Resolution of the Flow/Survival Debate and the Impacts of Flow Augmentation and Water Withdrawal in the Columbia/Snake River System" -- by Dr. James Anderson of the University of Washington, "provides useful and timely information relevant to the upcoming consultation between NOAA Fisheries and the Bureau on the effect of the Upper Snake River projects on listed salmon and steelhead," says Norm Semanko, executive director of the IWUA, in his Dec. 8 letter to the regional administers for NOAA and the Bureau.

"Please include this information in the record as part of the preparation for any Biological Assessments or Biological Opinions on those projects," requests Semanko.

Semanko adds that the "data and analysis …is also relevant to the prospective litigation regarding the use of storage water from the Upper Snake River projects as mitigation for the Federal Columbia River Power System. We request that this paper be included as part of the record on the remand of the 2000 Biological Opinion on the FCRPS."

Anderson, an associate professor at University of Washington, directs the UW's Columbia Basin Research (CBR) project in the School of Aquatic and Fishery Science.

The paper, dated Dec. 4, is the newest set of results arising from the CBR's ongoing analyses of flow and survival, Anderson said. He said much of the paper is a synthesis of recent efforts, with most of the research supported by the Bonneville Power Administration, NOAA Fisheries and the Army Corps of Engineers.

Anderson said the IWUA did not provide funding for the report.

The paper takes a look at flow/survival analyses by the CBR, the Columbia Basin Fish and Wildlife Authority, and NOAA Fisheries, and considers reviews of such work by the Northwest Power and Conservation Council, Independent Science Advisory Board and National Research Council.

"This paper discusses these analyses," writes Anderson in the introduction, "and demonstrates that the information now exists to resolve the issue of the impacts of flow augmentation and water withdrawals on smolt survival."

The 2000 Biological Opinion for the Columbia River hydropower system calls for flow targets at Columbia and Snake River dams to be met by flow augmentation from reservoirs, and fewer water withdrawals. The intent is to decrease travel time for juvenile salmon and, therefore, increase survival through the hydro system.

Anderson, in analyzing the data and others' research, concludes that "travel time contributed generally less than 5 percent to the reservoir survival through the hydrosystem. Neither fish travel time nor travel velocity, both of which correlated with flow, were important factors in determining the change in survival within years or between years."

Anderson also looks at the impact of flow augmentation and water withdrawals on survival of fish in the estuary and ocean and 'delayed mortality."

The paper considers how "flow actions incrementally affect fish travel time and water temperature, two factors that may relate to delayed mortality."

Fish travel time, says the paper, "while not affecting survival in the hydrosystem, does affect the estuary arrival time and the total duration of exposure of the migrating fish to the river environment. Increased water temperature, besides affecting migration survival directly, can also increase the fishes' metabolic demand during migration. Together these factors could decrease the condition of the fish entering the ocean and so increase their mortality rate."

Anderson says that his smolt passage model (CRiSP) calibrated with 15 years of PIT-tag data predicts that "each change in flow by 1,000 cfs measured at Lower Granite Dam changes the spring chinook travel between the Salmon River and Bonneville Dam by 2 hours.

"Therefore, water withdrawals that decrease flow by 1,000 cfs would increase a 26-day travel time to 26 days and two hours. A one million acre feet flow augmentation from Dworshak Reservoir over a 40-day period would decrease the travel time from 26 to 25 days.

"Thus, water withdrawals should have unmeasurable and insignificant impacts on fish travel time and major flow augmentations should decrease travel time by less than 5 percent. Therefore, the effect of these actions on delayed mortality through a change in migration time is small to insignificant."

Regarding temperature, the paper says flow augmentation may "increase or decrease the water temperature."

Anderson notes that flow augmentation from Dworshak Reservoir decreases river temperature through the upper dams on the Lower Snake River.

"However, because river temperatures closely follow air temperatures, the temperature impact decreases with distance from the source of augmentation as the water equilibrates with the air temperature. The impact is greatest for fish traveling between Dworshak and Lower Granite Dam, but the effect of Dworshak water downstream is greatly reduced, and the impact on fish survival through the hydrosystem is very small."

The paper says flow augmentation from the Brownlee Reservoir on the Upper Snake can increase downstream river temperature, and have a "small negative impact" on smolt survival.

"Thus, over a two-week migration period, the total degree days of exposure of fish with flow augmentation in the Snake River is essentially the same as the exposure without augmentation," writes Anderson.

Impact of water withdrawals on river temperature, says the paper, may also be positive or negative, depending on whether the return flow is a higher (surface runoff, municipal waste) or lower (subsurface) temperature.

"The magnitude of change in river temperature is proportional to the amount of water withdrawn relative to the river flow," writes Anderson. "A 1 kcfs return flow that is one degree C warmer than a 100 kcfs river flow would increase the river temperature by 0.01 degree C.

"We are fairly safe in concluding that the impacts of water withdrawals of this magnitude have an insignificant and unmeasurable impact on river temperature and therefore on delayed mortality or direct in-river survival."

Semanko of the IWUA said he forwarded the work to the federal agencies because the issue of flow augmentation "is of critical concern to Idaho. There has been a wide range of reports and studies completed in the last year or two. It is of great benefit to have a credible, independent researcher have taken a look at all the research data and put it in perspective."

Bert Bowler, Native Fisheries Program Director for Idaho Rivers United, said the Anderson paper "runs counter to what's in the peer-review literature. The peer-reviewed research shows the flow augmentation has a positive benefit for fish."

Related Sites:
Anderson's full report

Bill Crampton
Idaho Water Users Stress New Paper on Flow Augmentation
Columbia Basin Bulletin, December 12, 2003

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