Nonpoint source pollution, also known as polluted runoff is one of the main threats to water quality in Wisconsin. It occurs when rain or snowmelt moves across or through the ground, picking up natural and human-made pollutants and carrying them into rivers, lakes, wetlands, and groundwater.- These pollutants include sediment, nutrients like phosphorus and nitrogen, fertilizers, oil, grease, and bacteria. They come from agricultural fields, urban areas, and residential properties.
- The Land & Water Conservation Department assists landowners and producers with installing conservation practices that will reduce sediment and phosphorous runoff.
Sediment - In farm areas, tilled fields are a major source of sediment. Conventional tillage leaves soil exposed, with little vegetation or plant residue to hold it in place, increasing erosion and runoff.
- Sediment pollution clouds the water, harms aquatic life, reduces water quality, and raises the cost of water treatment. It results from erosion that washes sand, silt, clay, and other materials into nearby water bodies.
- A single dump truck can hold up to 10 tons of soil (or sediment). Conservation practices implemented by Winnebago County LWCD prevent an average of 1,400 tons of sediment runoff each year.
Phosphorus
- Both urban and rural runoff contains phosphorus, a nutrient that promotes excessive algae and weed growth in water bodies. When phosphorus levels rise, it can lead to harmful algal blooms that disrupt recreation and damage ecosystems.
- Phosphorous can also be found in a soluble form. Urban sources of phosphorous include lawn fertilizers, pollen, leaves, grass and orthophosphate in vehicle exhaust.
- Just one pound of phosphorus can generate 300–500 pounds of algae. Conservation practices in Winnebago County reduce phosphorus runoff by an average of 2,700 pounds annually.
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