Bathymetric survey and physical and chemical-related properties of Raccourci Lake, Louisiana, July 1998 and April 1999

Raccourci Lake (Old River), an oxbow lake formed from an incomplete cutoff of the Mississippi River in southeast Louisiana, is a popular recreational lake used for water-based activities such as water skiing, fishing, boating, and swimming. The nearness of this large oxbow to Baton Rouge and its continued fishing productivity make it one of the most used lakes in southern Louisiana. An understanding of current hydrologic conditions of Raccourci Lake and other lakes and reservoirs in Louisiana is essential to the management and protection of these valuable natural resources. Water quality and quantity are important concerns to those who use these bodies of water for municipal, recreational, agricultural, or industrial purposes. Current and accurate information regarding the physical and chemical-related properties and conditions of freshwater lakes and reservoirs in Louisiana is fundamental to planners and managers for evaluating these resources. In October 1996, the U.S. Geological Survey, in cooperation with the Louisiana Department of Transportation and Development, began a study to conduct a bathymetric survey and determine the physical and chemical-related properties of Raccourci Lake.

The purpose of this report is to present the results of the bathymetric survey and the results of vertical profiles of physical and chemical-related properties, including depth, water temperature, dissolved oxygen (DO), specific conductance, and pH, which were measured at three sites in the lake. Hydrographic surveying software was used for combining differential global positioning system (DGPS) information with digital survey fathometer data to accurately map the bathymetry of the lake. The bathymetric map was produced using geographic information systems (GIS), and lines of equal depth of water were reviewed and edited for accuracy and consistency. On-site physical and chemical-related properties were measured at the three selected locations using a water-quality monitor. This report is one in a series of planned map reports describing current bathymetry and physical and chemical-related properties of lakes and reservoirs in Louisiana.