Colored dye added to Hangman Creek will help scientists understand water quality problems

SPOKANE - Scientists from the Washington Department of Ecology will use a harmless fluorescent dye to track how fast water travels through Hangman Creek as part of a larger effort to study oxygen and pH in the creek’s water this summer. “If residents see a reddish fluorescent tint in the creek during the week of June 15 or July 13, they needn’t worry,” said Joe Joy, an environmental scientist for Ecology. Joy added that “Using dye for this type of study is very common, and research has long shown that the dye does not affect human health or aquatic life in any way at the low concentrations we use.” Researchers will track the plume of the dye with an instrument that is able to detect the small amount of dye in the river. “This dye study is part of Ecology’s efforts to understand the causes of low dissolved oxygen and pH impairments in the stream” said Elaine Snouwaert, who is coordinating Ecology’s water quality improvement plans for the Hangman Creek watershed. Data collected from the flow test will reveal how low flows in the summer affect oxygen and water pH in a given stretch of the creek. The information will be used in computer models to help scientists understand the creek’s water quality problems. In the week following the dye studies, teams of Ecology researches will be collect water quality monitoring data during an intensive study throughout the watershed. Parts of Hangman Creek and several of its tributaries violate water quality standards for dissolved oxygen and pH, endangering fish and other aquatic life. Nutrients and sunlight contribute to conditions creating excessive weeds and algae growth that cause oxygen and pH impairments. Low stream flow makes these problems worse. Hangman Creek and its tributaries also fail water quality standards for bacteria, temperature and turbidity. Ecology published a draft plan to address these problems in April 2009. This will be finalized and submitted to the US Environmental Protection Agency for approval later this month.