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Resiliency is the focus of Lake Nokomis shoreline design project

Posted on 27 March 2018 by calvin

MPRB planning $450,000 project to improve shoreline and increase natural landscape

This project will enhance 4,800 linear feet of shoreline north of the west beach, around the lake and down the point on the east side. (Graphic courtesy of Minneapolis Parks and Recreation Board)

By TESHA M. CHRISTENSEN
Nearly $450,000 will be spent on plantings and other improvements around Lake Nokomis this year to improve the eroding shoreline and water quality. With this, invasive plants will be removed, and habitat developed.

Right now, a natural lakeshore buffer is absent or narrow in many areas. Aquatic vegetation is nonexistent in some areas, and water clarity less than one meter due to excessive nutrients.

The upcoming Minneapolis Parks and Recreation Board (MPRB) project includes 4,800 feet of shoreline that extends about 20 feet inland.

During the second community meeting held in February, MPRB project manager Jon Duesman outlined the problem and explained what will be done to fix things.

He stressed that this project will not address groundwater or surface water issues. A separate multi-agency group is working on that problem.

However, some residents question why any work is done before that issue is resolved, and lake levels better understood. Recently, the lake has had substantial variations in water levels. The ordinary high water level is 815.4, according to the Minnesota Department of Natural Resources.

“In the last seven years, we have seen drastic changes including dying trees, flooding, invasion of cattails, eroding beaches and shoreline to the lake,” pointed out Joan Soholt, who is part of a group of local residents seeking to address water issues in the Lower Minnehaha Creek Watershed.

“Shouldn’t we address the cause of this fluctuation before we put money into plantings and enhancements? It seems like putting the ‘cart before the horse’ to plant unless you resolve the lake level problem.”

Duesman pointed out that planners recognize that lake levels have been fluctuating. “We’re designing this to be resilient regardless of what the water levels do,” he stated.

More natural landscape
The Nokomis-Hiawatha Regional Park Master Plan approved in 2015 calls for increasing the amount of naturalized landscape around the lake by 10-50%.

“We’re looking to increase the quality and the quantity of these natural habitats,” remarked Doug Mensing of Applied Ecological Services (AES).

Much of the existing shoreline has turf grass and woody vegetation right up to the shoreline.

Current problems include a limit to upland and shoreline buffer habitat due to extensive turf and invasive species. Shoreline erosion is occurring in locations due to shading, wave action, trampling, and shallow-rooted vegetation. Aquatic habitat quantity and quality is limited due to little aquatic vegetation and poor water clarity. Plus, sediment and algae further suppress plant growth by preventing light penetration.

Photo right: During the second community meeting held in February, Doug Mensing of Applied Ecological Services (AES) outlined the problem along the Lake Nokomis shoreline and explained what will be done to fix things. (Photo by Tesha M. Christensen)

There is erosion near the north stormwater pipe, wet areas in the lawn, and concentrated run-off.

This project will enhance 4,800 linear feet of shoreline north of the west beach, around the lake and down the point on the east side. In doing so, the project will improve habitat for fish, birds, reptiles, amphibians and aquatic invertebrates while re-establishing the aquatic and shoreline vegetation that is critical to overall lake clarity.

Each shoreline area is divided into three areas to pick the right types of plants: upland buffer, shoreline, and emergent.

The upland buffer begins about two feet from trails to the wetland delineation line and includes mostly short mesic prairie and areas of wet prairie. The shoreline buffer is the space from wetland delineation line to water’s edge. Diverse native shorelines (including many pollinator species) will be planted in the upland and shoreline buffer areas.

Some plants in these areas remain from a planting project in 2005, but all of the emergent plantings from then have died.

A concern was expressed that the new plantings may die as the old ones did. Duesman replied, “We intend to have a very robust planting that is resilient.” He stressed that they do not want to waste money, yet everything they do is being done without knowing whether water levels will go up or down.

“We’ve heard this message loud and clear,” Duesman said.

The emergent wetland is from the water’s edge to depth of approximately two feet. It will include a diversity of shallow emergent species (such as river bulrush, lake sedge, giant bur-reed, and common three-square) near shoreline and transition to only hardstem bulrush out to the two-foot depth.

An online survey of residents showed that the majority preferred shorter, random plantings versus formal or taller plantings. While many of the more colorful plants won’t do well in this area, some bands of color will be included to provide seasonal variety.

Rip-rap toe protection will be used in two or three locations that get a lot of wave action, although MPRB is also evaluating the use of toe-wood, coir log with live stakes, and minor grading and soil lifts.

Eleven of the 18 accesses to the lake with erosion in this area will be removed during this project and filled in with plantings, while others will be modified to last better in the long-term. Durable lake access may include the placement of large, level stones.

Work to begin in September
Funding for this project was provided by the Outdoor Heritage Fund to restore, protect, and enhance Minnesota’s wetlands, prairies, forests, and habitat for fish, game, and wildlife.

The first phase of this project will be more simple, while potential future phases may increase the formality and number of limestone blocks used.

Work is slated to begin in September 2018.

Additional feedback is being collected via an online survey at www.surveymonkey.com/r/NokomisShoreline.

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