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Challenges of Watershed Implementation Plans: Joe’s Bayou Watershed

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Watershed ManWatershed Management to Meet Water Quality Standards and TMDLS (Total Maximum Daily Load) Proceedings of the 10-14 March 2007, San Antonio, Texas  701P0207.(doi:10.13031/2013.22471)
Authors:   Daniel N Moriasi, Jan R Boydstun
Keywords:   Implementation plan, Watershed, TMDL, BMPs

Joes Bayou watershed is located in the Ouachita River Basin, Louisiana and covers a drainage area of about 173 square kilometers. This watershed is listed on the 303(d) List for Louisiana as impaired for dissolved oxygen (DO) and nutrients. The TMDL report recommends a reduction of 89% of total non-point source loading to meet the DO standard of 5 mg/L. The main goal of this study was to identify the sources of pollution and recommend best management practices and strategies to reduce pollutant levels. Land use types in Joes Bayou include cultivated agriculture (72%), pasture-idle (16%), forestry (7%), and miscellaneous (5%). Based on limited data collected in 1999 and 2005, there was no overwhelming evidence to conclude that the watershed is impaired due to DO and nutrients. Possible reasons for this contradictory deduction include: 1) load reduction calculation is based on conservative critical condition and 2) a margin of safety to account for TMDL uncertainty, which may be unrealistic. Joes Bayou is also listed on the 303(d) List for Louisiana as impaired for total suspended solids (TSS), turbidity, and selected pesticides by EPA. The 1999 TSS and turbidity data analysis and a study completed by EPA in 2001 show that these impairments could have greater effects on water quality in Joes Bayou than the dissolved oxygen. However, the solution to the TSS and turbidity impairment may be somewhat related to that of DO impairment. Since pollution from agriculture was suspected of contributing to low DO, a high priority should be given to reducing NPS loading from farm fields. Consequently, agricultural BMPS found in Volume 6 of the State of Louisiana Water Quality Management Plan need to be implemented with a concerted effort by stakeholders within the watershed. Some of the challenges that need to be addressed include insufficient data needed for modeling.

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