What is a stormwater pond?

Stormwater ponds are a common sight in urban and suburban areas. They are constructed during the development process to safeguard water quality by collecting and treating water after a rain event.

There are two types of stormwater ponds located in Cambridge. The first type is called a dry pond and consists of a basin that holds water for 2-6 days, or until the treated water evaporates or settles into the ground.

The second type is called a wet pond and is designed to have a permanent pool of water all year. Stormwater ponds can be various shapes and sizes, depending on the site and the size of the area that is collecting runoff.

Why stormwater ponds are important

As land is developed vegetative cover is replaced by impervious surfaces such as buildings, roads, parking lots, and driveways. Instead of soaking into the ground, rainwater (i.e., stormwater) runs off the impervious surfaces very rapidly, sometimes resulting in flooding downstream.

In addition, as the runoff washes across Lawns, roads, and parking lots, it also picks up sediment. Stormwater ponds slow down the runoff so that flooding can be reduced and sediment can settle out in the pond rather than in lakes and rivers.

Management of the stormwater ponds

All stormwater ponds require maintenance. Regular maintenance of a stormwater pond involves upkeep of the stormwater pond and its immediate surroundings.

The city inspects each stormwater pond at least once every five years and from those inspections maintenance and repair plans are generated. When the pond adjacent to your property is scheduled to be maintained you will receive notification explaining when the maintenance will occur and what the maintenance will entail. Maintenance of stormwater ponds can include the following:

• Repairs to erosion and inlet/outlet structures (summer) this is done to prevent sediment from entering the pond through erosion.

• Removing trash and debris (summer) this is done to prevent the trash from entering our lakes and rivers.

• Trim trees, brush and undergrowth (winter and summer) this is done to allow the ponds to be exposed to wind and sunlight. Wind and sunlight are required to generate oxygen which is required for treatment of nutrients in the ponds.

• Dredging (summer) sediment is removed periodically to restore the usable volume needed to treat a specific amount of stormwater in the pond.

Recreational use of stormwater ponds

Stormwater ponds are potentially dangerous for recreational activities like ice skating and hockey because of unknown ice conditions. Stormwater ponds have a constant flow of water, which causes ice to form in unstable conditions over winter months. Although the Ice seems safe one week the fluctuating water levels of the ponds can quickly make the ice unstable. Please help us keep your family safe this winter by explaining to your children that it is extremely important to keep off the ice.


If you have any questions concerning stormwater ponds please contact city staff at: 763-689-1800 or www.ci.cambridge.mn.us.

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