Water: Nonpoint Source Success Stories
Nebraska (Section 319I - 1994)
Nebraska has a number of groundwater protection programs targeting nonpoint source groundwater contamination, evidenced by elevated nitrate-nitrogen concentrations. Heavy application of fertilizer and irrigation water on corn and other row crops has led to this serious threat to groundwater, Nebraska's main source of drinking water. Because sediment is the biggest threat to surface water, particularly lakes, Nebraska is linking various federal and state programs to establish best management practices in the watershed that will restore or protect the lakes.
Education Reaps Significant Improvement in Groundwater
The Central Platte Valley, a major corn producing region, was receiving heavy applications of nitrogen fertilizers and intensive irrigation. These activities, along with the area's coarse sandy soils and shallow water table, significantly contaminated the groundwater with - nitrate-nitrogen.
Over the last several decades, the state has documented nitrate-nitrogen accumulation in the Central Platte - Valley. Some areas of the Central Platte Natural Resources District's (CPNRD) have averaged nitrate-nitrogen groundwater concentrations of 18.9 parts per million (ppm), with isolated sites reaching as high as 40 ppm (EPA level for safe human use is 10 ppm). Since groundwater provides essentially all the area drinking water, this rising nitrate-nitrogen concentration poses a serious threat to both municipal and private water supplies.
In 1987, the CPNRD developed a comprehensive groundwater management plan to comply with the Nebraska Ground Water Management and Protection Act of 1986. Under the plan, the CPNRD designated a district-wide groundwater quality management area where it could regulate nitrogen fertilizer application and irrigation to reduce nitrate-nitrogen accumulation.
Convincing farmers that the recommended nitrogen and irrigation BMPs would not harm their yield and would save them money in the long run was a necessary step in gaining their confidence and support. The Central Platte Valley Groundwater Management Program was the first program in the state to address the issue of alleviating nitrate-nitrogen contamination in Nebraska's groundwater and serves as a model. Education, partly supported by section 319 funds, has increased compliance with the CPNRD regulatory program and contributed to a significant improvement in water quality. The management area has three distinct phases based on nitrate-nitrogen concentrations in the underlying groundwater. Some important areas, such as municipal wellheads, may be assigned to a more restrictive phase even though - concentrations are below normally required thresholds.
The least restrictive are Phase I areas, defined by groundwater with 0-12.5 ppm nitrate-nitrogen concentrations. Producers are banned from applying nitrogen on sandy soils in fall and winter and must attend training classes to become certified to apply - nitrogen fertilizers. Education and demonstrations encourage voluntary compliance with recommended BMPs for nitrogen fertilizer and irrigation water applications.
In Phase II areas, with 12.6-20 ppm nitrate-nitrogen in the groundwater, producers must be certified, test soils and irrigation water annually for nitrate-nitrogen content, and file annual management reports. They are prohibited from applying nitrogen to sandy soils in fall and winter. However, compliance with recommended nitrogen and irrigation water BMPs is voluntary. In Phase III areas, with more than 20 ppm nitrate-nitrogen in the groundwater, producers must meet all Phase II requirements. They are also prohibited from applying nitrogen in fall and winter on all soil types and must split spring applications of nitrogen or include an inhibitor.
CPNRD received a five-year section 319 grant in 1990 that supports a program to teach farmers about nitrogen and irrigation management techniques which reduce nitrate- - nitrogen pollution of groundwater and yet maintain acceptable crop yields. The project consists of educational programs, demonstrations, individual assistance, and monitoring to assess progress. The project's goal is to generate support for and compliance with the groundwater quality management area recommendations and requirements. The educational efforts gained farmers' confidence that the recommended nitrogen and irrigation water BMPs were credible. As a result, both voluntary and mandatory compliance with groundwater quality management area requirements have increased.
Nitrate-nitrogen levels in groundwater, increasing at an average rate of 0.5 ppm per year since 1960, began - declining in 1989 at an average rate of more than 0.3 ppm per year. An average decline of more than 1.0 ppm has been achieved in three years (Fig. 7-3). Monitoring, another component of the 319 grant, showed leveling of nitratenitrogen concentrations from 1991 to 1992, likely caused by excessive leaching of nitrate-nitrogen due to unusually wet conditions. Similar results are expected for 1993. In addition to improving the groundwater, these management techniques also helped farmers save money, which more than offset the added expense of soil and water testing. In 1992, district farmers saved approximately $1.6 million by applying less fertilizer and still maintained acceptable levels of crop yields.
The program's success in convincing farmers that the recommended nitrogen and irrigation water BMPs are credible and desirable has inspired other natural resources districts to adopt similar programs.