Rain Gardens

About Rain Gardens

Rain gardens are gardens set in bowl-like depressions and filled with native flowers, grasses, shrubs, and trees. They are designed to reduce the amount of stormwater that enters into lakes, rivers, and streams through the storm sewer system. In a residential setting, a rain garden might catch water from a roof and driveway before it runs into the streets and storm sewers. Many of the rain gardens in Saint Paul’s parks are much larger in scale and collect rainwater directly from the storm sewers.

Why does it matter if stormwater runs into the lakes and rivers?

As it falls on lawns, roofs, driveways, and streets, rainwater picks up pollutants such as motor oil, nutrients from fertilizer, and sediment. None of these are good for lakes and rivers. Excess nutrients in lakes leads to an increase in the amount of algae, known as an algal bloom. The algae use up a large amount of available oxygen, leaving less and less for the fish, eventually killing them off entirely. Lastly, a decrease in the number of fish in the water leads to a decrease in waterfowl and other wildlife in and around the lake.

Before humans extensively developed this land, much of the rainwater fell to the ground and was absorbed by the soil and plants. Now that much of the land in Saint Paul is impervious to water, lakes and rivers are overloaded with stormwater during rain events. This causes problems for the vegetation growing along the shoreline because they have to deal with constantly fluctuating water levels. It also means that less water makes it into the water table.

Learn about local rain gardens and what it takes to make one