New Video Highlights the Ups and Downs of Growing Communities

"When Development Comes to Town" is an animated video directed toward local decision makers that tackles some of the challenges and opportunities presented by growth in our small communities. Developed by the Lower St. Croix Watershed Partnership and East Metro Water Resources Education Program, this fast-paced video runs through a gauntlet of topics in about ten minutes, introducing the viewer to concepts ranging from shoreland ordinances to Minimal Impact Design Standards (MIDS). This video masterfully weaves together complex insights and downhome practicality with just the right amount of visual interest and is a 'must watch' for new, or even experienced, elected officials, staff and planning commission members for local governments. Click the link and enjoy! When Development Comes to Town

Contact Chris Lord, District Manager, This email address is being protected from spambots. You need JavaScript enabled to view it. with questions. 

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Enhancing Street Sweeping to Improve Water Quality

Street sweeping doesn't just improve the appearance and function of your neighborhood's roads; it's also one of the most cost-effective ways to reduce nutrients, sediment, and other pollutants entering our lakes, rivers, and wetlands. Common materials such as leaves, yard waste, sand, road salt, vehicle fluids, litter, and other debris accumulate in street gutters and have nowhere to go other than down the storm drain and, eventually into local waterways – flushed in by water during snowmelt and storm events.

Many cities complete street sweeping twice per year: once in the spring to remove solids from winter road treatment, and again in the fall to remove fallen leaves. However, gaps in sweeping schedules give these pollutants time to re-accumulate and flush into storm drains (and thus downstream waterbodies) before they can be removed. Increasing the frequency of street sweeping can greatly reduce pollutant loads in stormwater, which is why the Anoka Conservation District has added enhanced street sweeping considerations to its "water quality toolbox".

Enhanced street sweeping analyses combine area-specific information such as tree canopy cover and storm sewer networks with research-based pollutant recovery estimates to improve recommendations for the timing, frequency, and location of street sweeping. This approach has recently been applied in the direct drainage watersheds for Martin and Linwood lakes. 

Find more information about the benefits of street sweeping here: MN Stormwater Manual: Street Sweeping 

ACD Contact: Breanna Keith, This email address is being protected from spambots. You need JavaScript enabled to view it. 

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Construction Complete for Anoka Rain Gardens

Four rain gardens were installed in a northern Anoka neighborhood as part of the City's 2022 Street Surface Improvement Project. Collectively, these gardens will capture nearly 10 acres' worth of stormwater runoff (over 700,000 gallons annually) which would otherwise drain untreated to the Rum River. Through this, sediment loading to the river will be reduced by 969 pounds/year, and total phosphorus loading will be reduced by 3 pounds/year.

Each garden provides additional ecological benefits through the planting of a diverse range of native species, creating several hundred square feet of rich pollinator habitat within the Rum River corridor. Species planted included butterfly weed, cardinal flower, swamp milkweed, red-osier dogwood, dwarf bush honeysuckle, and several others. 

Funding for project design was provided by the Metropolitan Conservation Districts Engineering and Technical Assistance Program, and funding for construction was provided by the City of Anoka and State Watershed-based Implementation Funding.
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Construction Underway for Anoka Rain Gardens

A thriving rain garden installed in Columbia Heights in 2018. With proper maintenance, native species planted in rain garden will fill the entire space within ~3 years.


Four rain gardens are being installed in a northern Anoka neighborhood as part of the City's 2022 Street Surface Improvement Project. Collectively, these gardens will capture nearly 10 acres' worth of stormwater runoff (over 700,000 gallons annually) which would otherwise drain untreated to the Rum River. Through this, sediment loading to the river will be reduced by 969 pounds/year, and total phosphorus loading will be reduced by 3 pounds/year.

Each garden will provide additional ecological benefits through the planting of a diverse range of native species, creating several hundred square feet of rich pollinator habitat within the Rum River corridor. 

The largest of the four Anoka rain gardens – a double inlet project which will treat stormwater from two adjacent roadways.

Funding for project design was provided by the Metropolitan Conservation Districts Engineering and Technical Assistance Program, and funding for construction is provided by the City of Anoka and State Watershed-based Implementation Funding. 

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Six New Rain Gardens in Fridley!

Construction is complete for six rain gardens at residential lots in the Rice Creek Terrace neighborhood in the City of Fridley. These rain gardens were placed at high priority locations to intercept and treat stormwater before it enters Rice Creek. The locations were identified during a Lower Rice Creek Stormwater Retrofit Analysis conducted by ACD in partnership with the City and the Rice Creek Watershed District. The rain gardens were funded by the RCWD's water quality cost share program and the City of Fridley. Landowners have all agreed to long-term maintenance of the gardens to ensure optimal and continuing stormwater treatment. 

Cumulatively, the six rain gardens are estimated to infiltrate 455,000 gallons of water, as well as remove 605 pounds of sediment and two pounds of phosphorus loading to Rice Creek annually. All six rain gardens are vegetated with native plants to maximize infiltration and provide the co-benefit of pollinator habitat. Additionally, one rain garden is located immediately adjacent to a trail entrance into Locke County Park, providing an excellent public education opportunity.

Over the next two to three years, the native plant plugs will get much bigger, filling the gardens with color and life. To see other rain gardens already installed throughout Anoka County, please see the virtual project tour on ACD's website. See photos of all six new rain gardens above. 

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Rain Gardens in the City of Fridley

Six rain gardens are being installed at residential lots in the Rice Creek Terrace neighborhood in the City of Fridley. These rain gardens are being placed at high priority locations to intercept and treat stormwater before it enters Rice Creek. The locations were identified during a Lower Rice Creek Stormwater Retrofit Analysis conducted by ACD in partnership with the City and the Rice Creek Watershed District. The rain gardens are being funded by the RCWD's water quality cost share program and the City of Fridley. Landowners have all agreed to long-term maintenance of the gardens to ensure optimal and continuing stormwater treatment. 

A rain garden under construction in the Rice Creek Terrace neighborhood, City of Fridley

Cumulatively, the six rain gardens are estimated to infiltrate 455,000 gallons of water, as well as remove 605 pounds of sediment and two pounds of phosphorus loading to Rice Creek annually. All six rain gardens will be vegetated with native plants to maximize infiltration and provide the co-benefit of pollinator habitat. Additionally, one rain garden will be located immediately adjacent to a trail entrance into Locke County Park, providing an excellent public education opportunity.

Watch for additional updates as construction is finalized. To see other rain gardens already installed throughout Anoka County, please see the virtual project tour on ACD's website. 

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Rain Gardens Benefitting the Rum River

Six new rain gardens are being installed this summer in Anoka and Ramsey to benefit the Rum River. The first was highlighted in June. The second is now complete! It is located on Oneida Street in Ramsey.

Each curb-cut rain garden captures water from the neighborhood streets, driveways, roofs and other surfaces. Prior to these projects the stormwater was discharged directly to the Rum River without treatment. Rain gardens are ideal in built-out neighborhoods where space is not available for stormwater ponds or other larger practices. 

Kyle and Jamie Leaf and family at the newly constructed rain garden in their front yard. The Leaf family will own and maintain the rain garden which treats stormwater from 7 acres of their neighborhood.

Funding for two rain gardens is a state Clean Water Fund grant and the Lower Rum River Watershed Management Organization. Funding for the other four is the City of Anoka as part of their 2022 street renewal project. 

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Rain Gardens Benefitting the Rum River

Six new rain gardens will be installed this summer in Anoka and Ramsey to benefit the Rum River. The first of them, on Washington Street, was completed the first week of June. Each curb-cut rain garden captures water from the neighborhood streets, driveways, roofs and other surfaces. Prior to these projects, the stormwater is discharged directly to the Rum River without treatment. Rain gardens are ideal in built-out neighborhoods where space is not available for stormwater ponds or other larger practices.

Funding for two rain gardens is a state Clean Water Fund grant and the Lower Rum River Watershed Management Organization. Funding for the other four is the City of Anoka as part of their 2022 street renewal project. 

Bowler family members Amanda and Connor at the newly constructed rain garden in their front yard (not pictured: Daniel Bowler). The Bowlers will own and maintain the rain garden which treats stormwater from 2.2 acres of their neighborhood.
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RAIN GARDENS IN THE CITY OF ANOKA

Street reconstruction projects often provide opportunities to install new projects that can benefit water quality in nearby waterbodies. In the City of Anoka, four curb-cut rain gardens are currently being designed in conjunction with a street reconstruction project. The designs are being done by ACD in partnership with the City of Anoka and landowners. The rain gardens will capture stormwater runoff before it enters the storm sewer system, which discharges to the Rum River.

High priority properties with large contributing drainage areas were targeted. Those properties with landowners willing to transition some yard space out near the road from turf grass to garden area and agree to provide maintenance are being considered for rain garden installation. Funding for design is provided by a Metropolitan Conservation Districts Engineering and Technical Assistance Program, and installation funding will be provided by the City of Anoka.

Watch for additional updates as designs are finalized and the rain gardens are installed. To see other rain gardens already installed throughout Anoka County, please see the virtual project tour on ACD's website. 

Curb-cut rain garden example
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Where will this snow go?

As spring snowmelt and rainwater rushes down your street and into the nearest stormwater drain, you may contemplate its ultimate fate and journey along the way.

In a natural landscape, much of this water would evaporate or soak into the ground – destined to support vegetation or join the groundwater below – while the remainder would move downward along the surface to nearby wetlands, lakes, and streams. In developed landscapes, impermeable surfaces such as roofs and pavement prevent water from soaking into the ground while manmade drainage networks rapidly channel it to local waterways.

Anoka County contains many interconnected lakes, wetlands, streams, and rivers that receive and transport stormwater. Unfortunately, many of these have experienced increased pollution, erosion, and flooding as a result. Management practices such as rain gardens, bio-swales, and storm ponds have been established throughout the county to intercept stormwater pipes and ditches, decreasing the pollutant load and total amount of runoff entering our surface waters.

Ultimately, all of Anoka County drains into the Mississippi River – either directly from the land near its banks, or indirectly through its many tributaries (such as Coon, Cedar, and Rice Creeks, and the Sunrise, Rum, and St. Croix Rivers). The path that stormwater takes to these major rivers is unique to each neighborhood, city, and watershed; the figures below show examples of stormwater drainage scenarios common in Anoka County. 

  ACD pursues a variety of projects that reduce the amount of untreated stormwater entering our waterways; learn more about these by viewing our interactive projects map here. You can also help reduce the amount of pollutants entering your neighborhood's stormwater by following the practices listed here.

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Water Quality Improvements Constructed for Coon and Martin Lakes

One rain garden and two stormwater pond renovations were completed in November to treat stormwater before it reaches Martin and Coon Lakes. The projects will collectively treat 39 acres of residential development that previously were draining to the lakes with little or no treatment. They will keep 2,100 pounds of sediment and 5 pounds of phosphorus from reaching the lakes each year.

These waterbodies were priorities because both lakes are surrounded by homes and heavily used for recreation. Martin Lake is nearing the criteria for being removed from the State's list of impaired waters. Coon Lake has good water quality but is under pressure.

The rain garden was constructed in cooperation with a residential landowner along Hupp Street. Their property is a key location where drainage from 8 acres converged and entered a catch basin that piped stormwater to Coon Lake. Curb cuts on each side of the catch basin now intercept that water, allowing it to soak into the ground within the rain garden. Pollutant removal is estimated to increase by 52% compared to the pre-project condition. Mulching and planting of the gardens will be delayed until spring 2021 due to cold temperatures early in fall 2020. The property owners will maintain the garden.

The stormwater pond projects are redesigns and renovations of older ponds. Both ponds are on Martin Lakeshore within township-owned property. Both basins had filled with sediment over time and were providing little water quality treatment. Now, the basins are even larger than originally constructed to maximize pollutant removal. Pollutant removal is estimated to increase by 84% and 104%, respectively, at the two ponds. Linwood Township will own and maintain the basins.

These projects are part of a State Clean Water, Land and Legacy grant to the Sunrise River Watershed Management Organization. The Anoka Conservation District is managing the projects. Additional funds remain and will be used for similar projects in 2021.

Collaborators on these projects included the ACD, SRWMO, Martin Lakers Association, Linwood Township, and the City of East Bethel.

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Stormwater Treatment Projects Being Constructed at Coon and Martin Lakes

By the end of September 2020, both Coon and Martin Lakes will have new treatment of stormwater before that water reaches the lake. Two stormwater ponds at Martin Lake are being renovated. One new rain garden at Coon Lake is being constructed.

The two stormwater ponds already exist on the shores of Martin Lake at 228th Place and 230th Avenue (see map). Like a full vacuum cleaner bag, they have captured as much sediment and nutrients as is possible. To call them "ponds" today seems generous. Each will be made deeper than the original design, like replacing an old, full vacuum cleaner bag with an empty, bigger bag. Pollutant removal will be more than 50% greater than when the ponds were originally designed and new. Water reaches the ponds by pipes that capture water from several acres of surrounding neighborhood, including roads.

The rain garden at Coon Lake will capture curbside water that today is piped to Coon Lake without treatment. The curb will be cut creating entrances to the approximately 1 ft deep basin. Sandy soils allow quick infiltration of the water. A special underdrain ensures no standing water. Native plants create a garden appearance. The owner of the property on Channel Lake has agreed to maintain the garden.

Images show project locations and condition of the stormwater ponds before renovation.

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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.

Failed rain garden that doesn't drain between rain events

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
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.
Ideal rain garden

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.
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.

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.

Thriving curb-cut rain garden that easily drains within 48 hours
Failed rain garden that does not drain between storms

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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