The diversion of freshwater from the Mississippi River is intended to mitigate saltwater intrusion from the Gulf of Mexico and to lessen the concomitant loss of wetland areas. Though effective, freshwater diversion can affect wildlife and habitat; therefore, prediversion and postdiversion data collections are necessary to identify effects. The Davis Pond freshwater diversion area is located between the Mississippi River and Bayou Lafourche and extends to Barataria Bay Basin, Louisiana. Results and interpretations from the prediversion biomonitoring done in 2001 - which included data on fish, eagles, and bivalves - are presented in the U.S. Geological Survey (USGS) Scientific Investigations Report 2008-5067, "Davis Pond Freshwater Prediversion Biomonitoring Study: Freshwater Fisheries and Eagles." The postdiversion data generated approximately 6 years later from the sampling of fish whole bodies are presented here in this USGS Data Series. An accompanying log of postdiversion study site photographs was also produced in USGS Data Series 605, "Photographic Images Captured While Sampling for Bald Eagles near the Davis Pond Freshwater Diversion Structure in Barataria Bay, Louisiana (2009-10).This table compares the pre- and postdiversion trace element contaminant levels recorded at Davis Pond Freshwater Diversion with similar measurements taken at another freshwater diversion site in southern Louisiana. Caernarvon Freshwater Diversion was made operational in 1992. It is located less than 25 miles to the east of the Davis Pond site. To monitor the effects of the diversion on wildlife and water quality, scientists studied fish in the area before and after the diversion began running (1990-1994). A report summarizing the results of these tests, the "Caernarvon Freshwater Diversion Contaminants Monitoring Study, 1990-1994" (Conzelmann and others) was published in 1996. Contaminants levels described in this report were compared with the pre- and postdiversion results at Davis Pond. This table depicts the range of contaminant levels found in sampled fish pre- and postdiversion at Davis Pond, and pre- and postdiversion at Caernarvon. Results are grouped for easy comparison of changes occurring over the life of each diversion, and between diversion areas.
