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Hangman Creek Water Quality Tracked With Dye

SPOKANE, Washington, September 8, 2008 (ENS) – This week, scientists from the Washington state Department of Ecology will begin using a fluorescent dye to study flows in Hangman Creek, also known as Latah Creek. The information is being gathered in an effort to understand how to improve water quality in the creek.

The Hangman Creek watershed drains approximately 431,000 acres and spans across the Washington-Idaho border, draining parts of four counties.

“We want residents along the creek to know that they needn’t worry if they see a slight reddish, fluorescent tint in the stream during the week of September 8th,” said Joe Joy, an environmental scientist for the state agency.

“Using dye for this type of study is very common,” Joy said. “And research has long shown that the dye does not affect human health or aquatic life in any way at the very low concentrations we use.”

Researchers will track the plume of the dye with a fluorometer, an instrument that is able to detect the small amount of dye in the river.

Data collected from the flow test will reveal how long it takes water to move through a given stretch of the creek. The information will be used in computer models to help scientists understand the creek’s water quality problems.

“This flow study is part of Ecology’s efforts to develop a plan that will address low dissolved oxygen and pH impairments in the stream,” said Elaine Snouwaert, who is coordinating the agency’s water quality improvement plans for the Hangman Creek watershed.

Parts of Hangman Creek and several of its tributaries violate dissolved oxygen and pH water quality standards, endangering fish and other aquatic life.

The flow study will help determine the cause of these impairments. Common causes of dissolved oxygen and pH impairments are excess nutrients or sunlight entering the stream. Low stream flow makes these problems worse.

Hangman Creek and its tributaries also fail water quality standards for bacteria, temperature and turbidity. The Department of Ecology is currently working on a plan to address these problems.

The Spokane County Conservation District, too, is working with local residents, interest groups, and government organizations to address water quality issues in the Hangman Creek watershed.

The impacts of population growth, agricultural production, fisheries, and water pollution will be addressed as the project team members work together to develop recommendations for managing water resource and water quantity in the basin.

Upstream influences, land use changes, as well as stream channel and flood plain alterations, over the last 100 years contribute to what district scientists call “flashy” flow conditions and unstable stream banks.

Flows in Hangman Creek range from summer flows as low as 10 cubic feet per second to peak flows in excess of 20,000 cfs. Maximum discharge in Hangman Creek occurs from December through April, resulting from warm Chinook winds that induce rain on snow events. These events produce high turbid flows that can last a few hours to several weeks and occur many times within a season.

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