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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The Benefits of Simple Lakeshore Practices

The Anoka Conservation District (ACD) recently installed a 70-foot lakeshore restoration project to mitigate active erosion at a property on the east side of Martin Lake in northern Anoka County. This section of property is heavily used by the family and was a priority to keep intact. The shoreline had receded/eroded back, with certain areas experiencing severe undercutting caused by wave action. These vulnerable sections could lead to additional property loss in the future and contribute to pollutant loading into Martin Lake, further degrading water quality. 

As designed, this project should stabilize the shoreline and allow new vegetation to become established from existing native sources. It is estimated that the project will prevent 1.3 pounds/year of phosphorous from entering the waterbody throughout the life of the project.

Coir logs are designed entirely of natural materials that are made to biodegrade into the soil overtime. The material is inexpensive, durable, and able to be shaped uniquely to the shoreline. Coir logs can be purchased in different densities, lengths, and diameters, depending on the erosion situation. Compared to other types of erosion control practices, coir logs are low in cost and can be installed by landowners without professional guidance. These practices are also easy to maintain because landowners can fix individual sections that may be damaged over time.

Coir logs protect against wave action and allow banks to stabilize while encouraging vegetation growth. Sections of coir logs are installed in a continuous line near the bank and secured into place using wooding stakes which will also naturally degrade. Aquatics plants are commonly planted into the coir log to provide more enhancement.

This project was funded by the landowner and the ACD cost-share program. ACD provided project administration, design services, and project installation. 

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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 Lake George Shorelines Stabilized and Naturalized

The Anoka Conservation District has completed work with six landowners on Lake George to correct shoreline erosion and install native plant buffers. 483 linear feet of shoreline were treated with rock rip rap, coconut fiber biologs, shoreline plantings, or other techniques. The result is 5.9 fewer pounds of phosphorus and 4.8 fewer tons of sediment entering the lake each year.

Lake George water quality is a priority. The lake is heavily used by the public due to a large county park and many homes on its shores, and good water quality. That water quality has been experiencing a slow decline over time. Projects such as these help maintain water quality and also add near-shore habitat that benefits fish and other wildlife. The recently installed projects are further intended to be demonstrations of lake-friendly landscaping for other shoreline homeowners. 

The six project sites were selected from amongst 34 homeowner who expressed interest. Sites were chosen based on degree of erosion, benefit to the lake, and other factors. Funding was from a Watershed Based Implementation Funding grant to the Anoka Conservation District with matching funds from the Upper Rum River Watershed Management Organization and landowners.

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New Cedar Tree Revetments on the Rum River

Cedar tree revetments are a cost-effective bioengineering practice that can be used to stabilize actively eroding riverbanks. ACD staff in partnership with the Conservation Corps of Minnesota (CCM) installed a cedar tree revetment in Rum South Regional Park in the City of Anoka in July 2022. 

Erosion at the site was dominated by bank undercutting-- the beginning stage of a more serious issue. Excessive erosion along riverbanks threatens property, contributes sediment and nutrients to the receiving water body, and eliminates wildlife habitat. 

Installation of the 550-foot revetment and live bare-root plants will slow or stop the erosion and reduce the likelihood of a much larger and more expensive project being needed in the future. Cedar brush was also installed to provide additional soft armoring. Not only do revetments help protect against erosion, they also provide excellent habitat.

Pollution reduction from this project is estimated to prevent 24.75 tons of sediment and 21.03 pounds of phosphorus from entering the Rum River annually!

Funding for this project was provided by the Conservation Partners Legacy and a CCM crew labor grant funded by the Clean Water, Land, and Legacy Amendment. ACD provided project management and construction oversight throughout the process.  

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KNOW YOUR SHORELINE

Minor erosion at the toe of slope exposed during low water. If the erosion is addressed early, larger bank failures in the future may be avoided.

If you live on water, whether it be a lake, river, creek, or stormwater pond, low water during the summer months can provide a great opportunity for you to conduct a quick inspection of your shoreline condition. The very bottom of your shoreline, where it meets the water, is called the toe and is the most critical part for stability.

Low water often exposes the toe of the slope and allows you to identify areas of concern. For example, you might observe undercutting, where the lowest portion of the bank has been scoured away by flowing water or wave action. When problems are caught early, the solutions are often much simpler and cheaper. Addressing erosion concerns early also helps prevent more severe bank failures down the road.

Another good time to inspect your bank is in the fall once leaves have fallen and before snowfall. You can inspect the upper portions of your bank for problems like rutting from concentrated overland flow over the top of the bank.

If you have any questions about your shoreline or think a site visit may be warranted, please contact ACD staff. We're here to help. 

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“Google River View”: 360° Photos Collected on the Rum and Mississippi

An actively eroding bank on the Rum River

Photos collected from near-shore zones on surface waters throughout the county serve as valuable tools for assessing lakeshore and riverbank conditions. Following a day in the boat with a 360° camera, these photos are uploaded to Google Street View, making them accessible to anyone. ACD then uses these them to compile erosion inventory reports, which describe erosion severity and stabilization project needs on high-priority waterbodies such as the Rum and Mississippi Rivers. Updated photos for these rivers were collected throughout the first week of May and are now available to view (alongside those captured in previous years) on Google Maps.  

While browsing through these photos, you are sure to see a beautiful river view. You may also notice banks currently experiencing noticeable erosion or, alternatively, portions that have recently been stabilized and planted with native vegetation.

A formerly failing riverbank at the Mississippi River Community Park in Anoka, stabilized and planted with native vegetation
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Assistance for Shoreline Erosion

ACD has a number of grant opportunities available for addressing shoreline erosion along both streams and lakes in Anoka County. If you have noticed your lakeshore migrating back on you over time, or perhaps once had a low walkable area along your river frontage that is now gone leaving only a steep drop-off, ACD may be able to help you design and even fund a project to protect your property.

The first step is a site visit to your property by ACD staff. Now is a great time to reach out to ACD to plan a site visit in the spring. We will assess your erosion problems, give you advice on how to address them, and see if your shoreline might fit into one of our various grant programs for financial assistance. Shoreline restoration does far more than just protect your property. It also protects the water resource you live on, and also enhances habitat for all of the wildlife that utilizes that resource! 

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Clean Water Funds for Eroding Rum Riverbanks

The Board of Water and Soil Resources (BWSR) is recommending $440,000 in funding to ACD from the Clean Water Fund[1] competitive grant fund for stabilizing eroding Rum Riverbanks. This funding will be used in conjunction with funds already received from the Lessard-Sams Outdoor Heritage Council[2] ($816,000 to ACD) and the DNR Conservation Partners Legacy[3] grant ($185,000 to Anoka County Parks) for Rum Riverbank stabilization and habitat enhancement projects. These three funding sources will cover projects of all sizes, from small banks only needing cedar tree revetments to large failing banks requiring sophisticated engineering and reconstruction. The funds from the Clean Water Fund grant will be prioritized for the latter.

With additional matching funds from Anoka County, the Upper and Lower Rum River WMOs, ACD and landowners, over $1.5M-worth of streambank projects will be installed over the next three years to help the Rum River. The Rum River is a highly prized resource in Anoka County, but it is on the brink of impairment for phosphorus concentrations, and it has extensive bank erosion. The sediment washing into the river from these eroding banks dirties the water, increases nutrients, and smothers habitat for aquatic wildlife. ACD performed a streambank erosion analysis[4] from 2017 to 2019 that led to this concerted effort by ACD and Anoka County to secure state grant funding and local matching funds to make a big push to help the River. 

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