LAKE FORK CREEK HYDROLOGIC UNIT PROJECT REDUCES POLLUTION IN PRIME BASS RESERVOIR

The Lake Fork Hydrologic Unit Project continues to improve the quality of water in Lake Fork Reservoir. Lake Fork is identified throughout the country for great bass fishing, and this state treasure was once thought threatened by contamination from more than 300 dairies housing approximately 45,000 animals on 65,0000 acres, on-site septic systems, and municipal waste treatment systems.

Through the cooperation of federal, state, and local agencies, local operators have installed more than 85 waste management systems; and many more operators are in the process of system upgrades. Many innovative practices such as improved stock trails and walkways and intensive grazing systems have been planned and applied in the watershed. In 1995 it was estimated that approximately 3400 acres which experienced high sediment and nutrient losses in the past had been converted to pasture and hayland, and pasture and hayland management practices were implemented on another 11,000 acres that year.

The Lake Fork Reservoir is used for boating and swimming, as well as fishing, and will potentially soon become a source of water supply for the City of Dallas. Media attention on the reservoir has heightened citizen's concerns about the reservoir water quality. The Lake Fork Creek Hydrologic Unit Project was initiated to reduce the non-point source water quality loadings to the reservoir. A major goal of the Project has been to reduce the fecal coliform levels in the reservoir to values at or below 200 colonies per 100 milliliters (mL) measured as a 30 day geometric mean not to be exceeded.

Since the beginning of the of the project in 1991 certain trends have been noted in the data collected by the Sabine River Authority within Lake Fork Reservoir. Dissolved oxygen (DO) levels as measured as percent of saturation have consistently increased at all sampling sites within the reservoir, indicating a potential decrease in decaying organic matter typical with manure loadings. DO levels at the beginning of the project were on the average 88 percent of saturation. In 1995 the DO content averaged 96 percent. Not only has the percentage increased, but also the rate of increase. During the first years of the project their was little more than one percent increase in saturation per year. In 1995, the rate of increase was almost four percent. The rates of increase are consistent with a system where positive responses to changes often take years to be reflected in environmental indicators.

Another positive trend has been noted in the fecal coliform levels measured by the Sabine River Authority. Average coliform levels measured as numbers of colonies per 100 mL have dropped from a reservoir average of 467 in 1991, to 332 in 1993, to 9 in 1995. These values show more than a 50 fold decrease in fecal coliform levels in the reservoir. During the 18 month period from January 1994 to June 1995, fecal coliform at the sampling sites in the reservoir never exceeded 108 colonies per 100 mL, almost half of the Texas Water Quality Standard set for Lake Fork Reservoir.

Not surprisingly, the ammonia, nitrate + nitrite, ortho-phosphate and total phosphate levels have remained unchanged in the reservoir throughout the project. Enriched aquatic systems often respond very slowly to reductions in nutrient flux due to the nutrients cycled within the system. Over time, decaying nutrient rich organics will be covered by bottom sediments and their nutrient content not accessible to the system. In 1995 it was estimated the project was reducing annual input to the reservoir of approximately 2,500,000 pounds nitrogen, 1,000,000 pounds phosphorus, and 3,500,000 pounds of potassium.

Ammonia-N, nitrate + nitrite, ortho-phosphate, and total phosphate levels from 1991 - 1995 averaged approximately 0.04, 0.15, <0.05, and <0.05, respectively. These levels are less than half (in some cases much less than half) of the state screening levels for these water quality parameters. The screening levels were identified by the state water quality agency where elevated levels of pollutants are a concern.

On-farm manure management and system installation efforts are complimented by an aggressive information and education effort in the project. Numerous "Walk-Abouts" for dairy producers have been well attended. The "Walk-Abouts" provide an opportunity for producers to interact with personnel from the participating agencies, and provide a forum for demonstrating practices in operation as well as the opportunity for identifying, discussing, and sharing of solutions to manure management problems. A second education effort has focused on outdoor workshops for producers where concepts such as manure and soil testing, manure spreader calibration, and manure utilization are presented.

The soil testing program in the Lake Fork Creek project has been particularly successful. Soil testing as a means of determining organic and inorganic fertilizer applications has increased almost 200 percent from pre-project levels. Benefits from the soil testing program include better utilization of manure nutrients and the reduction in the application of inorganic fertilizer on areas receiving manure. An unexpected result of the soil testing program is that many pasture and hayland fields once under fertilized are now receiving more fertilizer with resulting increases in yields and reductions in sediment and nutrient losses from the edge of the field.

REFERENCE

Brown, B and E Hansalik, Lake Fork Creek Hydrologic Unit Project - Annual Project Report Fiscal Year 1995, USDA - Consolidated Farm Service Agency and Natural Resources Conservation Service with the Texas Agricultural Extension Service (November 1995)