Rising river temps threaten Columbia River salmon

September 10, 2011

As summer temperatures peak into and above the 90s, the Columbia River often warms up to a pleasant 70 degrees or so; an ideal temperature for people looking to cool off or play in the water on a hot day.

As refreshing as it might feel to people, however, to Columbia River salmon the rising river temperature is a major threat.

Salmon are happiest in 41 to 55 degrees, notes Hood River-based Columbia Riverkeeper, which regularly collects water quality data from 64 sites throughout the Columbia basin. Now in its fifth year, the monitoring program uses trained volunteers to test for characteristics like temperature, pH, dissolved oxygen and fecal bacteria.

Riverkeeper noted that recent testing results show extensive breaching of Washington's water quality standards, particularly with regards to water temperature during the hottest period of the summer. Results show the river often hovers between 70 and 75 degrees through the heat of the summer, putting salmon and steelhead under significant stress, reducing growth rates and putting them at risk to disease and predation.

In response to its findings, Riverkeeper recently submitted data to the Washington Department of Ecology, which Riverkeeper said is required by law to use to conduct a statewide assessment of whether water bodies are meeting safety limits for swimming, fishing and threatened salmon species.

"The new data shows that many sites on the Columbia River frequently reach 70 degrees; a temperature that is simply too warm for salmon survival," said Lorri Epstein, water quality director for Riverkeeper. "We have the data; the time is now for action."

Epstein said that, upon receiving Riverkeeper's data, Washington is now required by the Clean Water Act to take action to improve water quality to meet the safe limits.

"Ongoing monitoring is critical to understanding the health of the river and to ensure a rapid response when problems arise," she continued.

Riverkeeper noted that temperature is the most pervasive issue facing the Columbia River today, and it is arguably one of the biggest threats to the survival of salmon and steelhead. The high temperatures are a result of reduced flows, dams, loss of shade trees and thermal pollution from municipal and industrial outfall, power plants and stormwater.

Salmon can survive only if they have access to cold water, the agency stated. With the help of volunteers, it is working to identify, protect and restore cool water refuges that have become critical to the survival of salmon in the Columbia Basin.

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