Ponds with purpose
Often the small ponds seen in cities and developments are thought of as landscaping features to add beauty or increase wildlife habitat. While the ponds do that, their actual purpose is more intentional; they exist to protect lakes and rivers from pollution.
The #1 cause of pollution
These ponds are made to collect stormwater runoff. Stormwater runoff is rainwater or snowmelt that runs off of streets, parking lots, roofs and lawns. This runoff is the #1 cause of water pollution in the United States. Stormwater ponds capture and treat this runoff and its pollutants (heavy metals, sediment, bacteria, oils and nutrients). They prevent pollutants from getting in to lakes, rivers and wetlands and also reduce flooding by soaking up the excess water.
Why is my pond green?
Green ponds usually mean algae which is caused by excess phosphorus, a nutrient. Because stormwater ponds capture phosphorus and other pollutants they will rarely be pristine. Homeowners can unknowingly increase phosphorus levels in ponds adding to the greenness. See tips below for preventing this.
Another cause of green is duckweed. Duckweed is often mistaken for algae but it’s actually great for the pond. Duckweed is a tiny, free floating green plant that can form thick blankets across a pond. It’s an important food source for birds, bugs and other life. Duckweed is so good at filtering water it is even used in water treatment plants. So if its duckweed greening your pond, relax and enjoy the wildlife and water treatment it brings.
Prevent pollution in ponds
To prevent pollution and too much algae, protect the buffer around the pond. A buffer is an area of plants about 6 feet wide around the pond. Buffers slow stormwater runoff and filter pollutants. Protect buffers by leaving trees, shrubs and other plants around the pond. Do not mow down to the water’s edge, this increases erosion and phosphorus in your pond.
- Limit the use of fertilizers and pesticides near ponds. Fertilizers will add to algae blooms.
- Pick up and dispose of pet waste. Pet waste has bacteria and will add to algae blooms.
- Do not dump grass clippings or leaves in the pond. This will also add to algae blooms.
- Do not pour chemicals, oils, etc. in or near the pond.
- Sweep driveway and sidewalk debris into lawn or gardens; do not hose it into the street.
- Capture stormwater runoff from roofs and driveways in rain barrels or raingardens.
For more information visit www.co.carver.mn.us/ponds