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U.S. Geological Survey scientists will inject a harmless, bright red fluorescent dye into the auxiliary lock at Locks and Dam 14 on the Mississippi River near Pleasant Valley, Iowa, June 13, weather permitting. If needed, a backup date is scheduled for June 27.
The goal of the dye study is to understand how well water mixes within the lock chamber, to quantify the amount of leakage into and out of the lock through the gates, and to determine how quickly the dye becomes diluted downstream once released from the lock. Such information is used by federal, state, and local agencies for various engineering applications.
The red dye—known as Rhodamine WT—will be injected into the filling system of the auxiliary lock and may be visible for about a mile downstream along the Iowa shoreline. More dye will be added periodically throughout the day.
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. During the study, dye concentrations will be measured at several points in the lock chamber and downstream of the lock by bank and boat-mounted equipment.
Researchers will measure the distribution of the dye in the auxiliary lock and map the dyed water downstream after the dyed water in the lock is released. This study is not expected to impact the operation of the main lock at Locks and Dam 14 or cause any navigation delays in the area.