The Kansas River provides drinking water for multiple cities in northeastern Kansas and is used for recreational activities. This dye-tracing study will provide a better understanding of how quickly water flows from one location to another. Water-resource managers use this information to effectively respond to potential critical events such as harmful algal blooms or contaminant spills that may make the water unsafe for the public to use.

“Recent events with spills above intakes in rivers have pointed out the need for travel-time data to monitor and respond appropriately,” said Tom Stiles, Bureau of Water Director at the Kansas Department of Health and Environment. “With so many people dependent upon surface water supplies in Kansas, understanding how those rivers move is critical to proper water management.”

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The red dye—known as Rhodamine Water Tracer (WT)—will be injected into the Kansas River during low, medium and high-flow conditions in Manhattan, Topeka and Eudora throughout this study. The injection will occur at Eudora, Kansas on September 29. The dye will pass out of the river on September 30. The red-hued dye may be visible to the public as it moves downstream. Scientists will measure the amount of dye using instruments in the stream and laboratory analyses.

The potential of a contaminant being accidentally spilled into a river upstream from water users is a possible although minimal risk. The ability to predict the time it will take for a contaminant to reach a specific location is needed so that water-resource managers and municipal water suppliers can appropriately respond. Knowledge of streamflow speeds and travel times may greatly aid in proactive adjustment of water-treatment plans and public notice of unsafe water-quality conditions.

“Results can be used by resource managers to make informed decisions during a hazardous event that may affect water resources and public-water supplies,” said Chantelle Davis, USGS scientist. “Understanding how water moves within the Kansas River is critical in helping decision makers protect lives and property within our community.”

Rhodamine WT, which has been used in hydrologic studies for decades, is approved for use as a water tracer by the U.S. Environmental Protection Agency and is harmless to people, fish and plants at the concentration being used for this study. No impact to boats in the river is expected during or after the dye injection.