Phosphorus Monitoring



What is phosphorus and where does it come from?

Phosphorus has long been recognized as a major factor in plant and algae growth in Wisconsin’s lakes and streams. Small increases in phosphorus can cause substantial increases in aquatic plant and algae growth, which can harm the natural ecosystem and water quality. It can also reduce recreational use, property values and human health. Despite this, phosphorus is a widely used nutrient with varying sources and applications in industries we may not realize.

At its core, phosphorus is a naturally occurring nutrient. It’s used in detergents, animal feed and fertilizers, and is found in our food and our waste. Through its broad uses and sources, phosphorus can reach our waterways through “point” or “non-point” sources and can originate from human-made or occur naturally in the environment.

Point sources consist of piped wastes such as municipal and industrial wastewater treatment plants that release liquid effluent to lakes and rivers or spread it on fields; and from natural sources, including wetlands or past phosphorus loads building up in lake bottoms. Non-point pollution occurs when heavy rains and melting snow wash over farm fields, feedlots, streets and parking lots. This carries with it fertilizers, manure, excess soil and contaminants from urban areas which eventually feed into lakes and streams.

What is USRWA doing about it?

Before 2015, phosphorus sampling in Wisconsin’s waterways was only done sporadically due to the costs associated with it. Monitoring phosphorus levels in water requires testing from a lab to ensure accuracy, and multiple tests through the year create more reliability at a given site.

Through grants from the WDNR and the help of the Water Action Volunteers, Upper Sugar River Watershed Association has been performing monthly testing for total phosphorus in streams/rivers around the watershed since 2015 from May through October. A total of 21 sites were sampled in from 2015 to 2017.