Water-quality campaign targets lawn fertilizer, animal waste

Starting in April, city billboards and bus shelters will showcase a new public service campaign to inform citizens about water-quality issues. Funded by the Minneapolis Park and Recreation Board and the City of Minneapolis, water-quality education programs are part of the National Pollution Discharge Elimination System (NPDES) permit requirements.

The summer of 2001 marked the first time graphics developed by the Washington State Department of Ecology were used for billboard and bus-shelter public service announcements. This year, three messages will be displayed locally using the Washington graphics: Responsible use of fertilizer and picking up pet waste will be featured in the spring; the fall campaign will concern car washing and how it affects water quality in city lakes.

Many people believe that storm water is treated before it enters lakes and rivers. However, water that runs off sidewalks, parking lots, streets and other hard-surfaced areas flows through the storm-sewer system and directly into lakes and rivers. That means fertilizers, leaves, grass clippings, fluids from vehicles, pet waste, car-washing soap and litter that are left on streets, sidewalks and driveways can end up in city lakes.

Minneapolis and other cities in the metro region have recently passed no-phosphorus turf fertilizer ordinances, intended to help reduce the phosphorus that enters surface waters. When it comes to fertilizing, your lawn may not actually require an annual fertilizer application. Before you decide to fertilize, have a soil test taken to determine the amount of nutrients your lawn needs. Soil tests are available for a minimal fee through the University of Minnesota Extension Service Hennepin County, which can be contacted at (612) 374-8400.

Fertilizer that is washed into the storm-drain system reduces the water quality in our city lakes by contributing phosphorus to water. The three numbers printed on the fertilizer bag indicate the amount of nitrogen, phosphorus and potassium in the fertilizer. Of the three nutrients in turf fertilizers, the amount of phosphorus needed by grass is much less than nitrogen or potassium. Minneapolis soils are generally high in phosphorus to begin with, making applications of phosphorus to lawns unnecessary.

Phosphorus is a food source for algae, small green plants that live in lakes and streams. Increased levels of phosphorus leads to increased algae growth. Large amounts of algae in lakes are called "blooms" or "scums." Too many algae are harmful to a lake, blocking sunlight and preventing other aquatic plants from growing. Algae, as they die and decay, also take away much-needed oxygen from fish.

Pet waste and car-wash soap are often not thought of as impacting water quality; however, both contain phosphorus. Using a commercial car wash, where the soap goes into the sanitary sewer instead of the street and storm drain, is one solution to the car-wash pollution problem. As for pet waste, a city ordinance requires that you pick up after your pet. Pet wastes not only contain phosphorus but bacteria as well. Likewise, the droppings of waterfowl, such as geese and ducks, contribute phosphorus and bacteria to the water. Hand-feeding geese and ducks at the lake results in large concentrations of waterfowl, who are in turn "depositing" phosphorus and bacteria in and around the lake.

Picking up after your pet and preventing litter, fertilizer, soaps and automotive fluids from reaching the street and storm-drain system are easy things we can all do to help keep our waters clean in the City of Lakes.

For more lawn and garden information contact the University of Minnesota Extension Service Hennepin County at (612) 374-8400 or on the web at www.extension.umn.edu.