MOSCOW, Idaho – Helicopters with infrared surveillance devices swooped over the Palouse countryside over the weekend, measuring the temperature of streams to determine if they comply with federal standards meant to protect fish and other aquatic life.
The flights are scrutinizing 65 miles of the north and south forks of the Palouse River and Paradise Creek in Idaho and Washington.
They’re being organized by the Washington Department of Ecology, and the city of Moscow is helping to pay for measuring the streams in Idaho.
The federal Clean Water Act helps set standards that streams in the Palouse watershed stay below temperatures of 64 degrees Fahrenheit.
With the measurements from the helicopters, officials are gathering information to decide whether to reduce temperatures to help fish and insect species – and limit the growth of microorganisms that can rob water of oxygen.
“We want to know the worst case,” said Elaine Snouwaert of the Department of Ecology’s office in Spokane. “That’s why we’re doing the measurements at this time of year.”
Officials hope to learn how streamside shade, runoff from irrigation, cool-water springs, groundwater, municipal effluent and other factors influence stream temperatures.
In the summer, the volume of water is naturally low, which can boost temperatures as shallow, slow-moving water warms in the sunlight.
“Above the city of Moscow, it wouldn’t surprise me if Paradise Creek is basically dry now,” said Les MacDonald, the city’s public works director. “The lower the stream volume, the more likely little pools are, and they can get pretty warm.”
In measurements taken last July and August, the temperatures of Paradise Creek in some areas ranged up to 71 degrees, MacDonald said.
State and federal agencies eventually could request voluntary changes, including asking landowners to plant vegetation along the sides of streams.
Traditionally, environmentalists have believed stream temperatures in the Palouse increased because conifers that grew along stream banks were cut down by homesteaders and the generation that followed.
Washington’s Department of Ecology also could require Pullman to cool effluent from its sewage plant, and the federal Environmental Protection Agency could do the same for Moscow.
Still, just what should be done remains open to debate.
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