DYE TRACER TIME OF TRAVEL STUDY

Residents located near Clarks Creek may notice a red dye in the water the week of Aug 5 as part of a Pierce County study. This dye is not harmful to public health, fish or the aquatic environment.

ABOUT THE STUDY
Pierce County staff and consultant scientists are conducting a dye tracer study to help measure and track the movement of water as it flows downstream. The study is being repeated in August 2020 after the annual Elodea (an aquatic plant) harvesting has been completed.
The results of the two studies will be compared to evaluate the impact of the Elodea harvesting on creek flow velocity and water surface elevation, and to support ongoing analyses of water quality in Clarks Creek.

WHAT THE PUBLIC WILL SEE
As the one-day study is being conducted, Rhodamine WT, a non-toxic fluorescent dye, will be added to the creek downstream of Maplewood Springs for about 30 seconds. This dye has been approved by the US Environmental Protection Agency for safe use in surface waters. 
A slug (brief pulse) of dyed water will then travel downstream. Measurement probes will record dye concentrations at several downstream locations throughout the day. As the dyed water travels downstream, it will become more dilute and dispersed. Even when it is diluted, the dyed water will have a red or pink color. All visual evidence of the tracer dye will be gone within 24 hours.