Watersheds Link Us All
A watershed is defined as an area of land that water flows across or under on its way to a single body of water, such as a stream, river, or ocean. Water connects geology, plants, animals and humans as it flows across agricultural land into waterways and eventually to coastal estuaries and the ocean. In a properly functioning watershed, water is captured, stored and released by the soil thereby minimizing large flood events, recharging groundwater supplies and providing for plants and animals. As water flows over agricultural land, it may pick up and carry pollutants such as sediment, pesticides, nutrients into rivers, estuaries and the ocean.
Potential Effects of Agricultural Runoff
It is important that every landowner address these potential losses from their properties because even though each individual landowner may contribute relatively little, the cumulative effect on the watershed by many landowners can be quite damaging to water quality and the lives that the water supports.
Excessive sediment in the waterways can smother underwater habitats and organisms, interfere with feeding, cover important fish spawning grounds (e.g. for steelhead and salmon) and fill wetland areas thus increasing flooding potential. Other pollutants also attach to sediment, including pesticides and pathogens.
Pesticides can be carried off farm with irrigation or rainfall runoff and can cause toxicity to aquatic organisms. Pesticides can influence the aquatic ecology & community and they can be carried up the food chain through bio-accumulation.
Nutrient runoff from lawns, pastures and agricultural fields can lead to excessive growth of certain plants and algae, thereby decreasing biological diversity. The excessive growth can clog waterways and lead to a depletion of dissolved oxygen in the water, which can eventually lead to fish kills. Nitrate can also leach into groundwater. Nitrate in drinking water is a prevalent problem in many agricultural areas.