College of Pharmacy at ULM

"Reduction in Nonpoint Source Contaminant Loads to Bayou Chauvin in the Ouachita River Basin"

Introduction

Bayou Chauvin, subsegment 080102 of the Ouachita River Basin, is on the 2000 305(b) court-ordered list as being impaired due to organic enrichment/low dissolved oxygen as well as the 1998 and 1999 court-ordered 303(d) lists for impairment due to nutrients, fecal coliform, total suspended solids, turbidity, siltation, and noxious aquatic plants. As a result, Bayou Chauvin is not fully supporting water quality standards for primary contact recreation, secondary contact recreation, and propagation of fish and wildlife. TMDLs for these parameters have been completed and suspected sources of impairment include natural and man-made nonpoint sources and municipal point sources.

Bayou Chauvin is located in northeast Louisiana, just north of Monroe, and is 94 square kilometers in area. Land uses in the Bayou Chauvin watershed consist of agricultural and pasture (45%), forest (39%; including forested wetland), and suburban development (12%). The bayou originally drained to the Chauvin Swamp east into the Ouachita River. The headwaters originate in a pooled reach of L-11 Canal just west of the junction of Caney Creek and east of Highway 139. During moderate to low flow conditions, there is a westerly flow through Chauvin Swamp to the Ouachita River. Bayou Chauvin cuts across Bayou DeSiard east of Joe White Road. West of Highway 165, Bayou Chauvin flows through a natural streambed to the Ouachita River levee and floodgate.

TMDLs indicate that significant reductions in nonpoint loading to the watershed are required to achieve water quality criteria. Additional evaluations are needed to determine the most likely sources of NPS pollution, such as sediments, nutrients, and fecal coliform, in the watershed and to identify localized hot spots to be targeted for effective BMP implementation. Successful TMDL implementation plans for this watershed must include cooperation from landowners, and BMPs will be encouraged through education and demonstration sites. For example, rock-plant filters have been constructed for other projects and have been very efficient in reducing fecal coliform loads.

Newly constructed vegetative buffers are useful in reducing agricultural runoff. Storm drain marking programs have been used successfully to reduce contaminants in suburban storm water runoff. Sidestream reservoirs and wetlands reduce fecal coliform by holding storm flow and increase infiltration and evapotranspiration. Roof gutters redirected to lawns instead of streets and porous rather than impervious driveways are examples of volume BMPs. Other BMPs include on-site ecoroofs, edge of parking lot biofilters and cisterns. These and other BMPs may be implemented at a scale adequate to achieve the load reductions as established in the TMDL.

Specific Goals and Objectives

The goals of this project are to identify specific sources of NPS loading to Bayou Chauvin watershed and implement BMPs to improve water quality. The objectives of the project are:

Use existing water quality data, TMDLs, and inventory mapping and reconnaissance surveys to select and target locations along the watershed that are likely to contribute to NPS loading.
Through targeted water quality monitoring, land use areas (agricultural/pasture, suburban, wetland) will be selected for implementation of BMPs and demonstration projects.
Develop educational outreach programs to inform land owners of NPS issues through workshops, demonstration projects, and organization and training of action groups (i.e., storm drain marking programs).
Monitor water quality changes after BMP implementation.

"Reduction of Pesticides and Nutrient in Bennett's Bayou Following Implementation of Best Management Practices (BMPs)"

Introduction

Bennett’s Bayou is located in the Ouachita River Basin in northeast Louisiana just east of Monroe, Louisiana. The Bayou is part of a watershed that includes Bayou Lafourche, Boeuf River, and portions of the Ouachita River. The Bennett’s Bayou watershed contains both urban and agricultural land use areas. The 1993 NPS Assessment Report and 1996 Water Quality Inventory Report indicated that these waterways are impaired due to pesticides, nutrients, suspended solids, organic enrichment and fecal coliform bacteria. During 2002, USEPA Region 6 developed Total Maximum Daily Loads (TMDLs) for dissolved oxygen and nutrients for Bayou Lafourche (subsegment 080904).

Bennett’s Bayou serves as the outlet for drainage of at least three NPS contaminant loads into Bayou Lafourche. One area is Chennault Park Golf Course which has been shown to be a source of NPS pollutants. For example, elevated levels of simazine were measured in surface water within the golf course and in an outflow ditch that discharges into Bennett’s Bayou (Table 1). Several levels were above chronic exposure limits to aquatic life (10 µg/L) and remained elevated for several months after application. Simazine is generally applied in October or November for pre-emergence control of winter annual weeds and in December through February for late post-emergence control of winter annuals. There were also elevated levels of nutrients such as orthophosphates in surface water flowing out of the golf course (data not shown).

Table 1. Levels of simazine in golf course surface water following rain events
Days post-application^a	Simazine (mg/L)
Days post-application^a	Pond 4	Outflow Ditch
7	21.0	5.9
43	37.0	44.0
76	5.7	4.7
^a Approximately 2 quarts/acre was applied once to golf course fairways and roughs.

Based on the monitoring data obtained from 7 months of sampling, a BMP was developed that included creating a wetland detention basin to capture and attenuate contaminant runoff from the golf course. This involved dredging the wetland to form sediment basins and reseeding with native plant material. The BMP was completed in the spring of 2006. The current proposal will evaluate the success of the wetland area in reducing simazine and orthophosphate levels in golf course runoff and eventually Bennett’s Bayou watershed.

This proposal also presents an opportunity to evaluate the long-term success of another BMP implemented in the Bennett’s Bayou watershed. In 1999, the ULM farm (formerly NLU), located upstream from the golf course, developed a BMP that included conservation tillage systems with nutrient and pesticide management, and grassed waterways. Water runoff samples collected during certain times of the year were found to have reduced sediment and other potential contaminants when originating from plots managed with conservation tillage techniques.

Pesticides were not measured in this project. Results of this demonstration project were disseminated to local farmers through agricultural field days and these techniques continue to be used for other crops at the ULM farm site. The present proposal will monitor selected water quality parameters and pesticides (i.e., atrazine) during rainfall events in Bennett’s Bayou to evaluate the continued success of these agricultural BMPs.

In 1998, LDEQ began working with the Louisiana Cooperative Extension Service to educate residents along Bennett’s Bayou about nonpoint source pollution. The focus of this project was urban pollution associated with lawns and homes (disposal of used oil and anti-freeze). Lawn care practices such as fertilizer and pesticide management was encouraged through education and demonstration sites. In addition, storm drain stenciling programs were implemented throughout neighborhoods. Milhaven Estates subdivision is one residential area located between the ULM farm and Chennault Park Golf Course. The success of these programs will be evaluated by measuring water quality of stormwater runoff entering Bennett’s Bayou. It may be necessary to provide additional information about nonpoint source pollution to the local homeowners and/or re-apply storm drain markers around the neighborhood.

Specific Goals and Objectives

The specific objective of this project is to track the success of several Best Management Practices (BMPs) that were implemented to reduce nonpoint source (NPS) nutrients and pesticides in the Bennett’s Bayou watershed (Figures 1 and 2). The objectives of this project are:

Monitor simazine and selected nutrients in surface water discharging through a BMP wetland detention basin at Chennault Park Golf Course.
Evaluate the long-term effect of agricultural BMPs implemented at the ULM farm by tracking appropriate pesticides and selected nutrients (i.e., atrazine) in runoff following application.
Determine the success of homeowner educational programs and storm drain marker programs implemented along Bennett’s Bayou by measuring selected contaminants from storm water runoff.