Sixteen years ago, staff at the Washington Conservation District (WCD) approached the Washington County Fair Board with a winning proposal. As the Fair Board prepared to add a fourth pole-barn to its property, the WCD suggested including four demonstration raingardens to capture and infiltrate runoff from the building’s rooftop. WCD worked with Washington County Master Gardeners to design and install the gardens, and the partners led walking tours to show off the new gardens during that summer’s fair.
Today, raingardens have become a common, and well-known strategy used to manage stormwater on residential and commercial properties. These gardens are strategically placed to catch runoff from rooftops, roads, and parking lots when it rains, and designed to soak water into the ground within 24-48 hours, leaving the gardens dry throughout most of the year. In addition to reducing runoff pollution to lakes and rivers, raingardens also help to recharge shallow aquifers, and provide habitat for birds and pollinators.
As raingardens surged in popularity, however, local communities quickly realized how challenging it could be to keep these new gardens looking good and functioning properly. To keep better track of raingardens on private property, partners began requiring operations and maintenance contracts for raingardens installed with grant funds or to meet permit requirements. These agreements typically require landowners to care for their gardens for 15-20 years, and include an annual visit from WCD or watershed district staff to make sure the gardens are still functioning properly.
The Washington Conservation District also created a raingarden maintenance program for city-owned gardens. For example, the City of Stillwater contracts with WCD to care for 48 raingardens each year. Typical maintenance includes removing sediment from inlets in the spring, cutting down old vegetation, and weeding invasive species. “It’s a pretty small contract ($3500) so we’re only able to visit most gardens twice during the summer,” says Cameron Blake, WCD’s maintenance coordinator, “but we’re also happy to meet one-on-one with nearby homeowners to provide advice and discuss concerns.”
Often, volunteers help to care for raingardens as well. In Stillwater, local residents have adopted roughly 30 community raingardens through the Adopt a Raingarden program (www.mnwcd.org/adoptaraingarden). Volunteers tend to gardens between WCD maintenance visits and notify staff if there are problems that need to be fixed. In Marine on St. Croix, the WCD and Carnelian-Marine-St. Croix Watershed District organize monthly planting and weeding events for volunteers that are helping to care for new raingarden, streamside, and wetland plantings.
During a recent raingarden maintenance workshop organized by Sustainable Stillwater, WCD landscape designer Brett Stoplestad talked with volunteers about common maintenance concerns. There had been a storm the night before, and Stoplestad pointed out piles of sediment on the road, sidewalk, and in the inlets. “The location of the sediment shows how the water moves into and around the raingarden,” he explained. “As rainwater flows into the raingarden, it picks up dirt, leaves, sand, and debris. It’s important to remove this sediment and debris periodically so it doesn’t clog the garden or smother the plants.” Other common raingarden maintenance needs include picking up litter, weeding, thinning out aggressive species, and replanting bare spots that develop over time.
To find resources and advice on raingarden maintenance, visit www.mnwcd.org/adoptaraingarden. Resources include a downloadable maintenance calendar for Google or Outlook with monthly reminders, a maintenance check-list, maintenance guide book, and resources to help identify common weeds.