Filter Strips

A filter strip is a strip of gently sloping grass or other stable vegetation strategically planted between streams, rivers, ponds, lakes, storm, drains and sinkholes. These strips are designed as a barrier to remove sediment, organic materials, nutrients, pesticides, and other pollutants carried in agricultural runoff water. The filter strip works by slowing water flow and allowing the pollutant or sediment to settle before it gets to the water. Larger sediment particles of sand and silt are removed first, while smaller particles such as clay take longer to settle and can still get through.

BMPs can be built into the farming strategy used as preventative measures. Some examples consist of identifying surface water or potential soil erosion locations prior to starting any farming activities. Other BMPs can be physically built into the land such as filter strips, runoff diversions, or silt fences. These preventative measures are set in place to avoid costly clean-ups and eroded soil.

Tall perennial grasses are more effective than short flexible grass at trapping sediments and pollutants. The effectiveness of a filter strip is dependent on the flow of water. If the water flow is shallow and even, the filter strip will be more effective. Over time, filter strips lose effectiveness due to a build-up of sediment but can restore filtering capacity through the regrowth of grass. Filter strips can also be useful with regulations or bylaws which have a required setback when using pesticides or herbicides near water.

Filter Strip Benefits

Both the environment and growers can benefit from the use of filter strips. The environment benefits due to the filtration process the filter strip creates by slowing agricultural runoff and reducing sediment, pesticides, and other pollutants from contaminating surface water. It also provides food and cover for wildlife from harsh weather. Filter strips also help reduce natural soil erosion from wind and water runoff.

Growers benefit from filter strips as they are easy to set up, have low costs, and require minimal maintenance. These strips can help reduce damage by flooding on neighboring properties and surface water. They can be aesthetically pleasing and reduce maintenance costs for drainage ditches. Filter strips are a good use of land that is not suitable for planting, and can also keep farm equipment away from steep dips in the land. They can provide a habitat for species such as bees, which are important for the pollination of several crops. Filter strips are also a technique used for field conservation and best management practicesfor water and soil conservation. These filter strips also have economic benefits through financial incentives set out by the USDA, like the Conservation Reserve Program(CRP).