Rum Riverbank Washout Stabilized Near Rum River Central Boat Ramp

In May of 2022, the Rum River reached its highest peak flow since 2001 following torrential rain events in Isanti and Mille Lacs Counties. The roadway to the boat ramp in Rum River Central Regional Park in Anoka County was inundated under feet of water. When the floodwaters receded, 90 linear feet of bank had completely washed out, threatening the roadway and boat ramp, and leaving and exposed eroding bank dumping sediment into the river. This section of washed out riverbank was stabilized using a Flexamat PLUS articulated concrete mat at the toe, and a regraded and native-seeded slope above. A rock barb installed at the downstream end will provide in-channel habitat for fish and invertebrates while also kicking flow out away from the boat ramp.

The Flexamat articulated concrete was chosen for this project because an immediately adjacent project installed in 2015 is still holding very successfully, even after the flooding. An advantage of Flexamat vs. rock is that the Flexamat has void spaces that allow vegetation to grow between the blocks, masking the concrete during low water conditions, and providing additional habitat benefit. Traditional riprap does not allow this vegetation growth, and can look like a rock wall during low water.

In the spring, we will add bare root seedlings of shoreland tree and shrub species to the project site. The native grasses and sedges seeded into the bank will begin to grow, and the whole bank will establish deep-rooted native vegetation which will keep the soil anchored for years to come. A video short of this project can be found on ACD's YouTube page: https://www.youtube.com/shorts/eUHBV5TSNi8. To see other streambank stabilization projects installed throughout Anoka County, please see the virtual project tour on ACD's website. 

Before (top) and after (bottom) of 90-feet of streambank stabilized at Rum River Central Regional Park.
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Stabilizing Riverbanks in Anoka

Construction is complete on six streambank toe stabilization projects on the Rum and Mississippi Rivers in Anoka. These sites have had significant and accelerating erosion in recent years due to sustained high water and recreational watercraft. Most of the sites lie between two popular boat launches on the rivers.

Cumulatively, over 720 linear feet of eroding riverbank was stabilized. The primary stabilization technique is rock riprap installed on the lower portion of the slope, with a seeded and blanketed vegetative zone above the rock. The primary immediate goal of these projects was to halt the backwards march of the riverbanks by stabilizing the lower portion (or toe). An additional vegetation component is planned for these sites in the following year(s) to help stabilize the upper slope, which is only subject to wave action during the highest water periods. This vegetative zone will be comprised of native woody species, as well as grasses, sedges, and forbs, to enhance the habitat and aesthetic value of the shorelines, while also providing deep root structure to anchor the soil in place above the rock. 

The projects were done via barge from the water, a first for ACD-managed projects. Many of these sites had been on our inventories, but were not cost-effectively constructible from land. With a contractor that can install projects from the water, concerns about equipment access between buildings and site restoration on individual properties are non-factors. Beyond stabilizing these six eroding shorelines, we are hopeful that this new construction technique opens up more potential streambank stabilization projects that would have otherwise not been possible or cost-effective from land. To see these and other streambank stabilization projects installed throughout Anoka County, please see the virtual project tour on ACD's website. 

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Stabilizing Riverbanks in Anoka

Construction is beginning on six streambank stabilization projects on the Rum and Mississippi Rivers in Anoka. These sites have had significant and accelerating erosion in recent years due to sustained high water and recreational watercraft. Most of the sites lie between two popular boat launches on the rivers.

Cumulatively, over 720 linear feet of eroding riverbank will be stabilized. The primary stabilization technique will be rock riprap on the lower portion of the slope, with a seeded and blanketed vegetative zone above the rock. This vegetative zone will be comprised of native species of grasses, sedges, and forbs to enhance the habitat and aesthetic value of the shorelines, while also providing deep root structure to anchor the soil in place above the rock. 

Mini excavator applying rock to a shoreline on the Mississippi River via barge

The projects will be done via barge from the water, a first for ACD-managed projects. Many of these sites had been on our inventories, but were not cost-effectively constructible in a typical fashion from land. With a contractor that can install the project from the water, concerns about equipment access between buildings and site restoration on individual properties are non-factors. Beyond stabilizing these six eroding shorelines, we are hopeful that this new construction technique opens up more potential streambank stabilization projects that would have otherwise not been possible from land.

Project updates will be provided as construction progresses. To see these and other streambank stabilizations projects already installed throughout Anoka County, please see the virtual project tour on ACD's website. 

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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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