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The lower San Joaquin River and south delta will take on a slight blush Monday afternoon, April 28, as scientists from the U.S. Geological Survey tint the river with a dye tracer. The non-toxic red dye, Rhodamine WT, will help USGS scientists track the movements of fish in the river and determine the effects of a fish barrier at the head of the Old River near Tracy.
The dye will be released into the river near Mossdale, about 12 miles south of Stockton, to help the Interagency Ecological Program, a consortium of nine state and federal agencies, evaluate the effects of a fish barrier at the head of the Old River. The barrier is installed temporarily during the spring of each year to help guide out-migrating fish away from the export pumps at Clifton Court and Tracy. The USGS scientists will study the movement of water near the barrier in an effort to help them better understand and track the movement of the fish.
Larry Smith of the USGS district office in Sacramento said the dye is likely to be visible in the channels of the south San Joaquin delta for at least a week after the release, but should have no effect on human or animal activities on or near the river. Smith said Rhodamine WT has been used in similar studies around the world for many years, with no ill effects.
Editors: For interviews with Larry Smith and other USGS scientists involved in the project, call Dale Cox at 916-278-3033.
