Agricultural Water Quality
In 1993, the Oregon State Legislature approved the Oregon Water Quality Management Act (Senate Bill 1010), directing ODA to help landowners reduce water pollution from agricultural sources and to improve overall water quality conditions. The focus of the Ag Water Quality Management program is on voluntary and cooperative efforts by landowners, Conservation Districts, Watershed Councils and others to protect and improve water quality. The Act outlines water quality conditions that agricultural activities are required to achieve. To implement the Act, the state was divided into 38 areas and a plan was developed for each area. The plans outline recommended practices to address soil erosion, riparian vegetation, and crop nutrient/animal waste management. The local area plans and regulations can be found on the ODA website listed in Additional Resources. The map on their webpage will help you determine your Management Area. In Benton County, you could be in the Middle Willamette, Mid Coast or Upper Willamette Siuslaw Areas.
Ground Water Management Area
The Oregon Department of Environmental Quality has designated parts of Benton, Linn, and Lane Counties as a Ground Water Management Area (GWMA) due to elevated nitrate in drinking water. The major sources of nitrate are fertilizer and manure, leaking septic systems, and nitrogen-fixation from the atmosphere. The purpose of the GWMA is to raise awareness about the health risk associated with elevated nitrate levels, establish voluntary programs to reduce ground water nitrate levels, and conduct research.
Flooding is a natural stream process. A floodplain is the nutrient-rich land that is inundated with water during floods. These areas allow flood waters to spread out and slow down, reducing their erosive force. This process encourages aquifer recharge as water seeps into the soil. A permit is required for all development in the 100-year floodplain.
Healthy riparian areas are vegetated borders found along streams, lakes and wetlands that provide the water body with shade, downed wood and organic debris. Although riparian areas cover only about 5% of the landscape, they are critical areas of plant and animal diversity. Typical riparian plants include alder, willow, cottonwood, salmonberry and sedges. Riparian vegetation provides key functions such as improved bank stability and water quality. Plants also slow the entry of rain and irrigation water into the stream and allow groundwater to recharge. Riparian areas are protected under the Agricultural Water Quality Rules and Forest Practice Rules. It’s very important to fence livestock away from riparian areas to help keep sediment, E. coli and other contaminants out of creeks. A riparian buffer should be at least 50 feet wide to trap eroding soils, 100 feet wide to filter pollutants, and 200-300 feet wide to provide wildlife with corridors for cover and travel. If you need to remove invasive plants from a riparian area, have a plan to replant the area promptly with native species. You may choose to eliminate weeds by mechanical means or use chemicals that are approved for use near water. Always follow directions on the label. Consider wildlife life cycles as you plan your management strategy. For example, delay mowing grassy areas until late July when birds are done nesting.
A wetland is an area where the soil is saturated with water, either permanently or seasonally. Wetlands may be covered by shallow water all year, or they may dry out during the summer. The three defining traits of wetlands are groundwater within the root zone during all or part of the growing season, hydric soils, and water-tolerant plants. Swamps, marshes, and vernal pools are a few types of wetlands. These valuable natural systems help maintain the ecological balance of a region. Wetlands filter pollutants, provide flood control, recharge groundwater, and provide wildlife habitat. If you are going to alter a wetland, you need a permit from the Department of State Lands.