USGS Hydrologic Study to Use Non-Toxic Dye in Lake Fork Creek

The U.S. Geological Survey Colorado Water Science Center will be conducting a dye-tracing study in Lake Fork Creek, west of Leadville, Colorado, between June 25 and 26, 2026. During this time, a non-toxic dye will be used in the stream between 7 and 9 a.m. and will be monitored throughout the day as it flows downstream.

The dye, known as Rhodamine WT, is a fluorescent dye commonly used in hydrologic studies and is non-toxic and safe for the environment. The dye will be released at a location south of Turquoise Lake and will be monitored at downstream locations by USGS hydrologists. Dye injection may result in a light pink to red color visible in the stream for approximately 12 to 24 hours after the dye injection. It is expected that minimal to no change in color will be visible in the stream to the south (downstream) of County Road 5A during the monitoring period.

This study is part of the USGS's ongoing research to evaluate effects of the Sugarloaf mining district to Lake Fork Creek. The focus area extends to about one-third of a mile downstream from the Sugarloaf Dam. The USGS is working in cooperation with the Bureau of Land Management, the State of Colorado, Trout Unlimited, the Natural Resource Damage Trustees of the California Gulch Superfund Site, Lake County, and the Arkansas River Watershed Collaborative. The USGS has received permission to conduct the dye-tracing study from the Bureau of Land Management, Lake County commissioners, Lake County Community Planning and Development, and private landowners.

Information on USGS studies of water resources in Colorado is available at https://co.water.usgs.gov.

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