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Studies Evaluate Polymer's Value in Protecting Fish and Wildlife From Toxin
Date Posted: October 2, 2001As part of the Department of Interior's National Irrigation Water Quality Program (NIWQP), the Service's Grand Junction (Colorado) Office is actively involved in work with selenium and its impact on fish and wildlife in the Uncompahgre, Gunnison and upper Colorado River basins. Selenium is an essential trace element that occurs naturally in the environment. Although small amounts of selenium are important for both wildlife and people, too much is toxic.
In 2000, the Uncompahgre Water Users Association (UWUA) sprayed a “sediment grabbing” polymer, polyacrylamide (PAM), onto 13 miles of irrigation canals prior to the water being diverted into the canals. Studies conducted by the U.S. Geological Survey within the drainage of the area affected by this treatment showed a 30% decrease in selenium and a 19% decrease in salt entering the drainage. Because of PAM's effectiveness and relatively low-cost, the UWUA ultimately would like to spray PAM on all of their canals and irrigation ditches on the East side of the Uncompahgre River. This area is the source of the highest amount of selenium entering local drainages.
The NIWQP is planning on locating another demonstration site for 2002 before making the decision to proceed with a basin-wide selenium/salt control project. Monitoring of canals downstream of PAM application areas will be designed into the next demonstration project. The goal of this monitoring is to determine how far PAM is carried downstream of its application area and what happens to that PAM. Other questions which need to be answered include:
1) Does the application method (i.e., spraying on dry canal bottom verses injection into flowing water) effect how far PAM is transported downstream?
2) How much PAM should be applied to get the most cost-effective selenium reduction?
3) What are the potential long-term environmental effects of widespread PAM application?
Last updated: June 12, 2015