Adopt-a-Drain is Coming Soon!

With all the snow on the ground, it's hard to think about spring, but we can't help it! We are so excited for the upcoming launch of a new program to Anoka County: Adopt-a-Drain! This program is empowering communities across the entire seven-county metro to protect their lakes, streams, and rivers by keeping vital storm drains clear of debris.

When the snow melts or when it rains, that water flows untreated into storm drains and straight into our lakes, rivers, and streams, taking with it any dirt and debris in its path. This polluted water, called stormwater runoff, harms wildlife habitat and hinders our recreational enjoyment of the Rum River, Coon Creek, the Mississippi River, and other waters across the county. With thousands of storm drains throughout Anoka County, residents can be partners in our efforts to protect clean water by volunteering to keep drains in their neighborhood clean.

Since many cities only sweep their streets in the fall and spring, common sources of pollution like leaves, grass clippings, dirt, litter, and road salt enter storm drains all year long. This pollution leads to potentially dangerous algal blooms and toxic conditions for fish, birds, insects, and aquatic plants. Storm drains are the link from our neighborhood streets to our local waters, so it's important to keep them clean year-round. By adopting the storm drains near your home, you can make a difference in keeping pollution out of your local lake or stream throughout the year.

The Adopt-a-Drain program is among the largest such efforts in the country and is organized by the Watershed Partners, watersheds, Soil and Water Conservation Districts, partnering cities, and other organizations that work together to educate others about water quality issues in their areas.

When residents sign up for the program, they'll receive an email with instructions on how to safely clear storm drains, dispose of the debris, and report the amount of debris they collect. Throughout the year, participants will receive a few friendly reminder emails and an annual report on local and metro-wide accomplishments to see the cumulative difference we are making together! To date, nearly five thousand residents in the metro have signed up to clean drains in their area. Collectively, these drain adopters have kept hundreds of pounds of pollution from entering local lakes and rivers. Will you be the next to join this growing movement?

Sign-up to be alerted when Adopt-a-Drain launches in your area. We look forward to partnering with you on protecting your local lake, river, or stream from pollution. Together, we can make a difference in improving the quality of water and quality of life in our communities.

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What we wish we knew: lessons for rain garden implementation

Over the last decade the Anoka Conservation District (ACD) has been involved in the design and construction of over 100 rain gardens in Anoka County. While the overwhelming majority fall closer to the 'ideal' end of the spectrum, we've been party to a few on the 'nasty' end as well. Properly functioning rain gardens often go unnoticed because they blend in with other landscape amenities. In contrast, the small fraction of 'nasty' rain gardens get the public's attention with nasty smells and mosquito problems. Rest assured, we've learned from our mistakes, refined our process, corrected the problematic rain gardens, and can confidently say we're now able to avoid the 'nasties'.

The lessons learned over the years have improved every aspect of rain garden location, design, installation, maintenance, and follow-up. These are our suggestions for other organizations designing and installing rain gardens.

Location

  • Rain gardens should be sited where they will capture runoff from a sizeable contributing drainage area that would otherwise make it into a priority water resource.
  • They should treat stormwater that isn't already routed to a stormwater pond or other installation for stormwater management.
  • They should be strategically located on properties where they will quickly fill during storms and quickly drain between storms.
  • They need to be located where they won't interfere with utility lines. Utility companies have minimum cover requirements over lines that may not be met following rain garden excavation. While some utilities like cable lines can be moved or lowered for a relatively low expense, others like gas and electrical lines can be cost-prohibitive to relocate when they conflict with the proposed rain garden location.
  • If a rain garden is installed in an area where the road routinely floods over the curbs, water will flow into the rain garden over the sides and cause erosion. It will also result in deeper water than intended, which will take longer to drain out.
  • If a rain garden receives water from a large neighborhood with non-natural runoff sources like irrigation systems or sump pump discharge, the rain garden may never have the chance to drain completely.
Rain garden pretreatment chamber

Installation

  • Curb-cut rain gardens are one of the few conservation practices where landowners volunteer to use their property to treat runoff from other properties. The landowner volunteering contributes relatively little to the problem and benefits relatively little from the solution. They also commonly assume maintenance responsibility for 10 years. For these reasons, local government should consider covering 100% of the construction costs.
  • Avoid equipment traffic within the garden.
  • Check soil infiltration rates. If they are under the design specification, loosen soil throughout the
  • garden with a four-foot auger.
  • Plant gardens in the spring and early summer, not in the fall.
  • Lay no more than three inches of mulch.
  • If possible, consider leaving the curb intact until the plants are established and then complete the curb-cut. Minimally, when installing a curb-cut rain garden as a retrofit, leave the curb intact until the basin is completed. This ensures the basin is stable and ready to receive runoff as soon as the curb-cut and apron are installed.
  • Install informative temporary signage during construction and permanent signage upon project completion that explains the value and function of the rain garden.
Community rain garden cleanup in Anoka county

Follow-Up

  • The sponsoring local government should connect annually with homeowners to remind them of maintenance needs, expectations, and flexibility.
  • Make sure homeowners know who to call if they experience problems.
  • Consider providing a maintenance program to help with plant replenishment or other incentive to keep gardens well maintained.
  • After the 10-year life of the garden, consider a refresh. Hire professionals to remove all plants, mulch, and accumulated sediment and debris, and power wash the retaining wall and pretreatment chamber. Then, add new mulch and replant, salvaging mature plants whenever possible. This relatively inexpensive investment can buy another 10 years of function.
'Nasty' rain garden

Design

  • For a standard rain garden, the water table should be at least five feet below the bottom of the garden. This will require an eight-foot-deep soil boring during the design process because the bottom of the garden is often two to three feet below the original ground elevation. Rain gardens with shallower water tables are feasible, but require an underdrain to function properly.
  • Soils should have high infiltration rates, generally one to three inches per hour. Rain gardens can be built in soils with lower infiltration rates, but may require an underdrain or a ponding depth shallower than 12".
  • If an underdrain is needed, install a control mechanism that allows variable draw down rates and levels. This provides a mechanism to capitalize on natural infiltration that may increase as the deep root structure of the native plant community matures and creates pathways for infiltration.
  • Water must be able to get into the garden consistently, predictably, and without causing erosion. The curb-cut should be sized to safely pass sufficient water volumes.
  • Utilizing a retaining wall along the back of the garden can improve the aesthetic appeal and allow the garden to store more water. Rain garden side slopes should be no steeper than 3:1. Therefore, for every foot of wall height, three feet of rain garden bottom is gained. In many cases this simple addition more than doubles the size of the garden.
  • Consider using a pretreatment chamber. A pretreatment chamber functions like a filter, capturing floatables like leaves, trash, seeds, and sediment to ensure rain gardens are able to properly receive water and dry between storms
Rain garden mid-construction, with a retaining wall and intact curb

Maintenance

This is a list of suggestions that can be provided to a homeowner after installation:

  • Get your neighborhood involved! If your neighborhood has several rain gardens, try to schedule a periodic neighborhood cleanup day.
  • Mulch will break down and should be refreshed every couple years.
  • Stay on top of weeding. Err on the side of pulling too much.
  • Homeowners should not be afraid to experiment with the plants in their rain garden. Try using native plants to encourage pollinator presence!
  • Pretreatment chambers should be cleaned out after each rain event. This should take no more than a few minutes.
  • Remove excess leaves in the fall. Having a few leaves is great for catching sediment and creating critter habitat, but too many leaves will create mats and slow down water infiltration.
  • Regularly remove sediment that makes it past the pretreatment chamber.
Ideal rain garden

When done right, rain gardens are an effective and beautiful method for combating pollution in lakes and streams, replenishing groundwater, and creating pollinator habitat. However, not every property or every homeowner is ideally suited to have a rain garden. While professionals at ACD can assess whether or not a property is a viable candidate, only the homeowner can decide if they are up to the task of maintaining a rain garden.

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What in the World is a Rain Garden?

  Rain gardens have popped up like weeds throughout the Twin Cities over the last decade to mitigate stormwater pollution in lakes, rivers, and streams. Despite their prevalence, the function and purpose of these little curbside gardens remain a mystery for many folks.

Downspout rain garden

Rain Garden Benefits:

Cities are very dirty. When it rains, stormwater picks up everything from feces to the motor oil that your neighbors spilled on their driveway. Many older neighborhoods were developed without stormwater treatment, so pollutant-laden runoff from roads, houses, driveways, and parking lots makes its way directly into rivers, lakes, and streams. Stormwater doesn't end up in a wastewater treatment facility or septic system like the water that drains out of your bathtub.

When functioning correctly, rain gardens protect natural water bodies from polluted stormwater, reduce flooding, recharge groundwater, and provide habitat for local pollinators. Rain gardens can be built to any size or shape to fit into the landscape of old neighborhoods where space is limited. They are relatively inexpensive to design and construct and can be maintained by homeowners who agree to take on that responsibility.

To treat all of the water in a neighborhood, it may be necessary to pepper the neighborhood with many small rain gardens, or put in a few larger gardens depending on available space and landowner interest. A well-functioning rain garden will dry out within 48 hours after a rain event, which keeps the plants healthy and prevents creation of mosquito habitat.

  Rain Garden Types:

There are two basic types of rain gardens, those built to treat water exiting a gutter downspout, and those built to treat road runoff. The first type, called a downspout rain garden, can easily be installed by a homeowner. This type of rain garden can prevent flooding around downspouts and allow rainwater to recharge groundwater.

The second type is called a curb-cut rain garden because an opening is cut into a roadside curb to allow water to flow off the road into the rain garden. When the rain garden has filled to the brim, the stormwater flowing along the curb will pass by and flow into the storm drain as it did prior to installing the rain garden. Curb-cut rain gardens are much larger, more complex, and should be designed and installed by professionals. Curb-cut rain gardens are more cost-effective because they only treat water that would definitely have made it into the stormwater system. For this reason, they are the only type of rain garden for which Anoka Conservation District currently provides assistance.

While traditional curb-cut rain gardens are built with the expectation that water will drain through the soil, some rain gardens are built in conditions that don't allow for water to drain quickly enough. In this scenario, an underdrain would be installed below the rain garden. The underdrain re-directs excess water from the rain garden into the street's stormwater drain to prevent the rain garden from flooding.

Curb-cut rain garden
Failed rain garden

Rain Garden Pitfalls:

Unfortunately, some rain gardens don't work as intended. Due to poor planning, faulty design, shoddy construction, or a lack of maintenance, some rain gardens fail to properly fill or drain. When done right, rain gardens are an effective and aesthetically pleasing method for combating pollution in lakes and streams, replenishing groundwater, and creating pollinator habitat. However, not every property or every homeowner is ideally suited to have a rain garden. While professionals at ACD can assess whether or not a property is a viable candidate, only the homeowner can decide if they are up to the task of maintaining a rain garden.
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Rain Garden Maintenance for Everyone

To function well, water needs to flow into the rain garden easily and soak into the ground quickly. While it's good to keep your rain garden beautiful, maintaining its functionality is crucial. Even an ugly rain garden can treat stormwater! Here are some helpful tips for maintaining your rain garden:

  • Get your neighborhood involved! If your neighborhood has several rain gardens, try to schedule a periodic neighborhood cleanup day.
  • Mulch will break down and should be refreshed every couple years.
  • Stay on top of weeding. Err on the side of pulling too much.
  • Homeowners should not be afraid to experiment with the plants in their rain garden. Try using native plants to encourage pollinator presence!
  • Pretreatment chambers should be cleaned out after each rain event. This should take no more than a few minutes.
  • Remove excess leaves in the fall. Having a few leaves is great for catching sediment and creating critter habitat, but too many leaves will create mats and slow down water infiltration.
  • Regularly remove sediment that makes it past the pretreatment chamber.
  • After the 10-year life of the garden, consider a refresh. Hire professionals to remove all plants, mulch, and accumulated sediment and debris, and power wash the retaining wall and pretreatment chamber. Then, add new mulch and replant, salvaging mature plants whenever possible. This relatively inexpensive investment can buy another 10 years of function.

Most importantly, don't be intimidated by maintaining your rain garden. There is plenty of room for trail and error. The more time you spend in your garden, the more comfortable you'll become with maintaining it!
Volunteers weeding a rain garden during a community rain garden cleanup in Anoka county
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