5.8.2 Minnehaha Creek Stream Restoration

The 2003 Minnehaha Creek Stream Assessment identified numerous areas of erosion along the length of the creek, as well as a general lack of steam complexity and lack of habitat for macroinvertebrates and fish largely driven by stream aggradation in impounded areas often upstream of artificial grade controls.  Based on these stressors and its flow regime Minnehaha Creek has been designated by the State as an Impaired Water for fish communities.  Minnehaha Creek is also listed as impaired for chlorides, dissolved oxygen, and bacteria (E. Coli).  The Minnehaha Creek Visioning Partnership identified erosion control, the improvement of conditions for aquatic life, and the improvement of aesthetic appearance as high priorities for future creek corridor management.  In 2012 the District completed a second Stream Assessment to evaluate the geomorphology and ecological health changes over time.  The 2012 Stream Assessment identified a general need for additional projects beyond those identified in the 2007 capital improvement program.  General recommendations for improving the ecological integrity, natural aesthetic and recreational value of Minnehaha Creek include but are not limited to: removing or modifying grade controls to allow fish passage and a more natural hydrologic condition; preserving and expanding wooded/vegetated riparian buffers along the entire stream length; reconstructing or remeandering channel and floodplain where space allows to improve geomorphic/hydrologic form and function and in-stream habitat; stabilizing banks using bioengineering techniques; establishing areas to preserve and enhance view-sheds; and establishing recreational corridor connectivity through passive uses such as trails and vistas.

Over the planning period the District will partner with riparian cities, property owners, other agencies, and infrastructure owners to accomplish stream restoration projects that will meet multiple objectives for water quality, biotic improvement, education and recreation.  Stream restoration projects would enhance riparian corridor vegetation; stabilize streambanks through bioengineering; add fish and macroinvertebrate habitat; create pool-riffle complexes; incorporate woody debris; remove select grade controls; and enhance educational and recreational opportunities through the creation of vistas and trail corridors designed to complement and protect the stable and restored streambank environment.

The CIP includes proposed improvements to several high-priority reaches as identified in the 2003 Minnehaha Creek Stream Assessment.   Priority reaches are those where stream restoration could improve streambank stability to ?Good? as measured by Pfankuch stability rating relative to Rosgen stream type, or those where the Stream Visual Assessment Protocol (SVAP) mean score could be improved to 5.0 or better, or by one full point.  Specific improvements are guided and refined by the results of the Minnehaha Creek Diagnostic Study, the Minnehaha Creek Biotic Integrity TMDL, the 2003 Minnehaha Creek Stream Assessment, the findings of the Minnehaha Creek Visioning Partnership, the 2012 Minnehaha Creek Stream Assessment, opportunities for partnership, future studies, and individual reach needs and opportunities.   Figure 20 illustrates the location of priority reaches based on the 2003 Stream Assessment.  Not all of these reaches were prioritized in the 2007-2017 CIP.  Those that were not included are Reach 2, Reach 11, Reach 18, and Reach 29. 

The list of specific reaches below reflects priorities determined based on available data to date.  However, over the term of this plan, the District: (a) may shift funds between projects included under 5.8.2 to reflect immediate priorities and work scheduling decisions; and (b) may identify and implement projects within other reaches or incorporate project elements consistent with the goals of 5.8.2, on determining that those goals will be met and pursuant to the procedures described below.  There are two reasons for the District to reserve this ability to adjust project implementation on the basis of its ongoing review: 

(a) The District's technical understanding of subwatershed hydrology and the hydraulic behavior of Minnehaha Creek will continue to develop and thereby refine the District's capacity to determine where and what sorts of improvements will be most cost-effective.  The ongoing work described on the preceding page and similar ongoing diagnostic work likely will identify additional sites that merit attention during the planning period.

(b) The Minnehaha Creek corridor is fully developed and land prices are high.  The riparian edge is intensively used by private homeowners and commercial/industrial uses in the upper corridor and by the public on Minneapolis Park and Recreation Board (MPRB) lands within the lower corridor.  Stream restoration methods may impede intensive use and involve concepts and aesthetics for which there is not yet universal acceptance.  Securing landowner participation or easements for stream work is an uncertain prospect, or project opportunities may arise in an unanticipated way and subject to the property owner's timeline.  Other opportunities may occur in the context of public road or utility work similarly driven by third-party time constraints.  The District accordingly must be prepared to respond to these opportunities.

Accordingly, the District intends to plan for and pursue implementation within the specific reaches enumerated below while also retaining the flexibility to pursue other opportunities as they arise.  With respect to the latter, there will be several project development elements to ensure transparency and public accountability:

(a) The District will continue to coordinate with the Cities of Minneapolis, Edina, St. Louis Park, Hopkins and Minnetonka and the MPRB to develop a more detailed understanding of hydrologic conditions in the subwatershed and Creek hydraulics and to confirm priority sites that meet District and municipal priorities. A focused feasibility study will be prepared for significant implementation actions to examine feasibility and cost-effectiveness.  The study will be made publicly available and presented to the Board of Managers at a public meeting with the availability for public comment.

(b) As described earlier in this plan, each year, for budget and levy purposes, the District will review the status of its capital program in a public forum with opportunity for public input.  Proposed revisions to the District's 10-year CIP will be provided to Hennepin and Carver Counties and all cities wholly or partly within the District.  At its budget and levy hearing, the District Board of Managers will make budgeting decisions that will set overall parameters for spending under this capital project 5.8.2 and set specific project implementation priorities for the upcoming fiscal year.

(c) Before expending levied funds on designing or implementing a restoration activity, the Board will distribute design plans and provide public notice for a public hearing and project ordering in accordance with Minnesota Statutes §103B.251.  If the proposed work will exceed $300,000, the District will afford the additional procedures set forth in section 6.8 of the watershed plan (page 84).

Project Reach 4 Restoration

Description

Streambank restoration, buffer reestablishment, enhancement of in-stream habitat features

Need

 

 

This reach extends from 34th Avenue South to the Lake Hiawatha outlet weir.  It contains a number of storm sewer outfalls that require repair or improvement.  The riparian corridor is mostly turf grass maintained to an eroding creek edge.  The reach scored a 4.1 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment, mainly due to poor condition riparian zone resulting in streambank undercutting and instability.  The reach includes spawning habitat, but lacks complexity of habitat features necessary to maintain a fish community.  The project would focus on improving the streambank stability and quality of the riparian area through bioengineering and native vegetation plantings as well as installation of in-stream habitat features. 

Outcome

Stabilized streambanks with both hard armoring and bioengineering to reduce erosion; improved riparian zone with native vegetation; improved fish and macroinvertebrate habitat; improvement in SVAP index to a score greater than 5.0.

Estimated

Cost and Funding

Design, construction, project management, vegetation management contract.  Funding source for this project is the District capital levy.

$944,100

Schedule

2013  Design, cooperative agreement

2014  Construction

Project Reach 6 Restoration

Description

Streambank restoration, buffer reestablishment, enhancement of in-stream habitat features

Need

This reach extends from the Hiawatha Golf Course bridge to the Lake Nokomis outlet, and flows through the Hiawatha Golf Course.  The riparian corridor is turf grass maintained to an eroding creek edge, with some riprap and a planted bank in one location.  The reach scored an extremely poor 2.9 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment, due to a poor condition riparian zone and lack of fish and invertebrate habitat.  The project would focus on improving the streambank stability and quality of the riparian area through bioengineering and native vegetation plantings that would not adversely impact play on the golf course.

Outcome

Stabilized streambanks with bioengineering to reduce erosion; improved riparian zone with native vegetation; improved fish and macroinvertebrate habitat; improvement in SVAP index to a score greater than 5.0 or at least one full point better than existing.

Estimated

Cost

Design, construction, project management, vegetation management contract.  Funding source for this project is the District capital levy.

$451,000

Schedule

2014   Design, cooperative agreement

2015   Construction

Project Reach 7 Restoration

Description

Streambank restoration, buffer reestablishment, enhancement of in-stream habitat features

Need

This reach extends from Lake Nokomis to Bloomington Avenue South.  It is channelized and stabilized with hard armoring.  A portion of this reach has been reconstructed with restored meanders and bioengineered banks.   The reach contains some erosion sites that require repair or improvement, including an exposed gas pipeline and a large box culvert whose discharge is creating erosion on the opposite bank.  The riparian habitat is poor, with some tree and shrub canopy and a narrow buffer of unmowed grass.  The reach scored a 4.8 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment, mainly due to poor condition riparian zone and the altered channel.  The reach includes some fish habitat, but weirs and riprapped channels likely serve as passage barriers.  The project would focus on improving the streambank stability and quality of the riparian area through bioengineering and native vegetation plantings as well as installation of in-stream habitat features.  The project would also evaluate the replacement of existing grade controls with a meandered, stepped pool design to improve habitat and eliminate barriers to fish movement. 

 

Outcome

Stabilized streambanks with both hard armoring and bioengineering to reduce erosion; improved riparian zone with native vegetation; improved fish and macroinvertebrate habitat; improvement in SVAP index to a score greater than 5.0, or an improvement of one full point.

Estimated

Cost and Funding

Design, construction, project management, vegetation management contract.  Funding source for this project is the District capital levy.

 

$654,800

Schedule

2011   Design, cooperative agreement

2012  Construction

 

Project Reach 8 Restoration

Description

Streambank restoration, buffer reestablishment, enhancement of in-stream habitat features

Need

This reach extends from Bloomington Avenue to Portland Avenue S.  It is an unstable channel with active cutting and deposition.  It contains a number of erosion sites that require repair or improvement, including an exposed gas pipeline.  The riparian corridor is mostly turf grass maintained to an eroding creek edge, although there are areas of the reach with good riparian woody vegetation.  Some streambank has been stabilized with hard armoring.  The reach scored a 5.8 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment, mainly due to poor condition riparian zone resulting in streambank undercutting and instability.  The reach has few fish habitat features.  The project would focus on improving the streambank stability and quality of the riparian area through bioengineering and native vegetation plantings as well as installation of in-stream habitat features. 

Outcome

Stabilized streambanks with bioengineering to reduce erosion; improved riparian zone with native vegetation; improved fish and macroinvertebrate habitat; improvement in SVAP index to a score greater than 6.0.

Estimated

Cost and Funding

Design, construction, project management, vegetation management contract.  Funding source for this project is the District capital levy.

$967,600

Schedule

2007  Design, cooperative agreement

2007  Construction

 

Project Reach 9 Restoration

Description

Streambank restoration, buffer reestablishment, enhancement of in-stream habitat features

Need

This reach extends from Portland Avenue to Nicollet Avenue S.   The riparian corridor is mostly turf grass maintained to an eroding creek edge in some portions of the reach and a healthy riparian forest in others.  The reach includes fish spawning habitat.  The reach scored a 5.6 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment, mainly due to the areas of poor condition riparian zone resulting in streambank undercutting and instability.  There are several locations where falling brick walls, riprap, culvert inlets, and improperly placed riprap are causing streambank erosion issues.  The project would focus on improving the streambank stability and quality of the riparian area through bioengineering and native vegetation plantings. 

Outcome

Stabilized streambanks with both hard armoring and bioengineering to reduce erosion; improved riparian zone with native vegetation; improvement in SVAP index to a score greater than 6.0.

Estimated

Cost and Funding

Design, construction, project management, vegetation management contract.  Funding source for this project is the District capital levy.

$877,700

Schedule

2014    Design, cooperative agreement

2015   Construction

Project Reach 12 Restoration

Description

Streambank restoration, buffer reestablishment, enhancement of in-stream habitat features

Need

This reach extends from Logan Avenue S to 54th Street.  It contains a number of storm sewer outfalls that require repair or improvement.  The riparian corridor is mainly turf grass maintained to an eroding creek edge and with some areas of stable banks with riparian tree and shrub growth.  The reach scored a 3.8 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment, mainly due to the poor riparian conditions and resulting unstable banks.   The reach includes areas with moderate in-stream fish habitat.  During the stream assessment, fish spawning was observed throughout the reach.  The project would focus on improving the streambank stability and quality of the riparian area through bioengineering and native vegetation plantings.

Outcome

Stabilized streambanks with both hard armoring and bioengineering to reduce erosion; improved riparian zone with native vegetation; improved fish and macroinvertebrate habitat; improvement in SVAP index to a score greater than 5.0, or an increase of one full point.

Estimated

Cost and Funding

Design, construction, project management, vegetation management contract.  Funding source for this project is the District capital levy.

$1,380,100

Schedule

2015   Design, cooperative agreement

2016   Construction

Project

Reach 14 Restoration

Description

Streambank restoration, buffer reestablishment, enhancement of in-stream habitat features

Need

This reach extends from France Avenue S to 54th Street West.  Much of the riparian corridor is turf grass maintained to an eroding or riprapped creek edge, but the upper 900 feet is wooded.  The reach scored a 5.8 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment, mainly due to areas with poor-quality riparian vegetation.   The project would evaluate construction of in-steam habitat features and options for improving the riparian zone with native vegetation buffers.

Outcome

Stabilized streambanks with both hard armoring and bioengineering to reduce erosion; improved riparian zone with native vegetation; improved fish and macroinvertebrate habitat; improvement in SVAP index to a score greater than 6.0.

Estimated

Cost and Funding

Design, construction, project management, vegetation management contract.  Funding source for this project is the District capital levy.

$896,000

Schedule

2011   Design, cooperative agreement

2012   Construction

Project

Reach 19-21 Restoration

Description

Streambank restoration, buffer reestablishment, enhancement of in-stream habitat features

Need

This reach extends from Meadowbrook Lake to Lake Street NE.  The reach has been channelized and straightened.  Where the Creek flows through Meadowbrook Golf Course, turf grass is maintained to steam edge.  The riparian corridor is a mix of turf grass and stable banks with riparian tree and shrub growth.  The reach scored a 7.0 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment, mainly due to fish barriers and lack of fish habitat, although spawning was observed during the assessment.  The project would evaluate the replacement of existing grade controls with a meandered, stepped pool design to improve habitat and eliminate barriers to fish movement.  Improvement of the riparian zone could include reforestation and establishment of native vegetation buffers.

Outcome

Stabilized streambanks with both hard armoring and bioengineering to reduce erosion; improved riparian zone with native vegetation; improved fish and macroinvertebrate habitat; improvement in SVAP index to a score greater than 7.0.

Estimated

Cost and Funding

Design, construction, project management, vegetation management contract.  Funding source for this project is the District capital levy.

$1,203,400

Schedule

2009   Design, cooperative agreement

2010   Construction

 

 

Overall Implementation Estimate (planning period):                                               $7,374,700