Tuesday, June 30, 2009

Water quality experts dye to learn more about Hangman Creek

Scientists with the Department of Ecology often need to find out exactly where water flows and how long it takes under certain weather and stream flow conditions. On June 15, 2009, researchers added dye to Hangman Creek and observed how it behaved. They did this to find out why there is so little dissolved oxygen in the stream and why the chemistry is sometimes unhealthy. They’ll do it again on July 13.

Researchers track the plume of the dye with an instrument that is able to detect the small amount of dye in the river. The data are now being plugged into a computer model to help us understand the creek’s water quality problems.

The information gathered from the flow test will tell us how low flows in the summer affect the oxygen and the chemical nature of the water in a given stretch of the creek.

But seeing that reddish fluorescent tint in the creek can be quite a shock to innocent bystanders who happen upon it. We could use your help to explain this process if you hear any alarm from friends when they see the dye.

Using dye for this type of study is very common, and research has long shown that the dye doesn’t affect human health or aquatic life in any way at the low concentrations we use.

Parts of Hangman Creek and several of its tributaries violate water quality standards for dissolved oxygen and pH (a measure of alkalinity and acidity), endangering fish and other aquatic life. Excess nutrients and sunlight contribute to conditions creating excessive weeds and algae growth that cause oxygen and pH problems. When the stream flow is very low in the summer these problems are even worse.

Check out the video to see our water quality expert, Joe Joy, dumping rhodamine dye into Hangman Creek at Kentucky Trails Road on June 16.

Thanks to Tighe Stuart of Ecology’s Spokane office for the video.

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