Stormwater Ponds

What are Stormwater Ponds?

Generally speaking, the term “stormwater pond” may refer to any constructed basin that is built for the purpose of capturing and storing stormwater runoff, either temporarily or for an extended period of time in order to mitigate downstream water quantity and quality impacts.Stormwater Picture   

In residential developments, you will often see small ponds throughout neighborhoods. The ponds are designed to look like natural lakes or wetlands, and as such are often mistaken for landscaping features. But they are there to prevent flooding and collect stormwater and pollutants like heavy metals, sediment, bacteria, oils and nutrients. The ponds collect and filter the water, keeping pollutants out of lakes and rivers.

Why is my pond water green?

1.  Stormwater ponds are highly engineered systems designed to reduce the risk of flooding and protect the water quality of our lakes, rivers, and wetlands.

Stormwater ponds decrease pressure on the storm sewer system by controlling the rate of water discharged downstream and provides treatment for pollutant-laden water before reaching our waterways.

As stormwater flows across hard surfaces, it picks-up and transports pollutants. Common pollutants found in stormwater include: 

  1. Leaves, litter, trash
  2. Grass clippings and yard waste
  3. Lawn-care products such as fertilizers or pesticides
  4. Sediment
  5. Pet waste
  6. Oils, greases, and automotive additives

2.  A green stormwater pond is a functioning pond. A green stormwater pond may appear to needBlue Green Algae Blooms        maintenance, but there are important characteristics to look for first that indicate it’s functioning as intended:

  • Duckweed: Duckweed is a tiny aquatic plant that floats on top of the water.  Duckweed can be identified by a leaf or cluster of leaves with small roots that hang down into the water. Duckweed is a valuable food source for waterfowl and turtles, however in proper conditions it can block sunlight and limit oxygen exchange for other aquatic plants. Duckweed grows in response to excess nutrients in the waterbody.
  • Algae: Pond scum, or filamentous green algae, is a green floating mass which is often found in dense mats resembling wet wool. This alga does not have roots and grows in response to excess nutrients in the waterbody. While this type of algae is non-toxic to humans, homeowners should not handle algae for risk of exposure to harmful bacteria. Cyanobacteria can be toxic and so adults, children, pets should avoid contact where there may be a bloom.
  • Odor: Decomposing plant and algae material contributes excess organic material resulting in a foul odor. This type of decay occurs in stagnant and poorly oxygenated water. You may notice the odor typically increases in warm, summer temperatures and subsides over time. 

What can I do to improve water quality in my stormwater pond?

Residents are encouraged to help improve pond health by taking the steps suggested below:

Green Slime on Stormwater Pond

  1. Maintain natural vegetation or sod on all bare areas.
  2. Add native plant species to filter runoff and absorb nutrients.
  3. Use phosphorus-free fertilizer and fertilize only as needed.
  4. Rake up trash, leaves, grass clippings, branches, and other yard waste off the street and curbs. 
       Properly dispose of debris by transporting to compost facility. 
  5. Use biodegradable soaps for outdoor cleaning and car washing.
  6. Reduce or eliminate winter salt use.
  7. Pick up and properly dispose of pet waste.
  8. Install a rain barrel to harvest rain for use on your lawn or garden.

  City of Buffalo's Responsibility

  •  The City of Buffalo maintains (140) stormwater ponds, (9) raingardens, (9) infiltration basins and (1) 
      underground system. 
  •  Inspections:  

     As required by the Municipal Separate Storm Sewer System (MS4) Permit and Stormwater Pollution Prevention Plan (PDF), the City of Buffalo inspects all stormwater ponds and outfalls to determine structural integrity, proper function, and maintenance needs. City-owned stormwater ponds are inspected every five years or 20% annually. Pond inspections typically begin in July.


Routine stormwater pond maintenance is necessary to ensure ponds function on a long-term basis. Pond maintenance varies from regular mowing to removing accumulated sediment. The city does not manage ponds for aesthetic purposes including weeds, algae, or odor. The city is not responsible for maintenance or repairs of privately owned ponds. 

City Policy:

Dumping grass clippings, yard waste, and pet waste into a stormwater pond is prohibited. 

Contact Information: 

Please contact the city with the following concerns: 

  • Report Maintenance Needs to Dumping of Pollutants: – Online (link) or (763) 682-1181
  • Please contact the city if suspicious odors, vegetation staining, or deposits are observed.