Water Quality

 

The Shingle Creek and West Mississippi Commissions’ Second Generation Watershed Management Plan shifts the Commissions’ focus from an emphasis on controlling the amount of stormwater runoff to an emphasis on protecting and improving the quality of water in the lakes and streams in the watersheds.  The Commissions also adopted new standards that require developing properties to infiltrate some runoff on site as well as to require buffer areas between new development and lakes, streams and wetlands.

 

Eight water management goals were identified in the Second Generation Watershed Management Plan:

v  Protect and improve water quality based on practical use.

v  Reduce erosion and sedimentation.

v  Maintain the existing 100-year flood profile throughout the watersheds.

v  Protect and improve wetlands.

v  Establish an education and public outreach program.

v  Protect and improve groundwater quality and promote groundwater recharge.

v  Strive to provide water quality that supports recreation, fish and wildlife based on practical use.

v  Develop an appropriate management strategy for Hennepin County Ditch #13.

 

The Commissions annually monitor the lakes and stream of the watersheds to assess the current status of water resources in their respective watersheds as well as to monitor progress toward accomplishing the goals set forth in their Water Quality Plan.

 

Currently, the majority of the Commissions’ water quality monitoring program is conducted in the Shingle Creek watershed where stream monitoring for water quantity and quality, lake monitoring, and macroinvertebrate monitoring is conducted.  The Commissions’ technical staff obtains most stream water quality data while volunteers collect most lake water quality and stream macroinvertebrate data.

 

TMDLs

 

Every two years, the Minnesota Pollution Control Agency (MPCA) releases the 303(d) list of impaired waters in Minnesota.  Named after the section of the Clean Water Act in which the impaired waters law is found, this list includes lakes, rivers and streams known to exceed water quality standards.  Shingle Creek was first listed for excessive chloride in 1998.  In 2002, twelve of the 16 lakes in the Shingle Creek watershed were included on the list for excessive nutrients.  In 2004 Cedar Island Lake, was added to the list and Shingle Creek was listed impaired by low dissolved oxygen levels.

 

Shingle Creek Chloride TMDL

 

Shingle Creek was the first stream in Minnesota to be designated an Impaired Water for excess chloride.  The high levels of chloride were discovered by the US Geological Survey during a special, intensive study of Shingle Creek as part of the National Assessment of Water Quality (NAWQA) program.  Chloride was not routinely monitored in Minnesota streams, but since this discovery in Shingle Creek, elevated levels of chloride have been found in many streams.  These levels are not harmful to humans but, at their extreme, they can be harmful to fish and other aquatic life as well as aquatic vegetation.

 

To determine what should be done to reduce chloride in the creek, the Shingle Creek Watershed Commission partnered with the Minnesota Pollution Control Agency (MPCA) to complete a special study called a Total Maximum Daily Load study, or TMDL.   Begun in 2002, the TMDL investigated all the potential sources of chloride, how they got into the creek, and how much they would have to be reduced to bring chloride in the creek down to acceptable levels. 

 

The Final Shingle Creek Chloride TMDL study found that most of the chloride in Shingle Creek comes from road salt applied to icy roads.  It is estimated about 85 percent of the chloride in Shingle Creek come from road authorities including cities, Hennepin County, and MnDOT.  The balance comes from groundwater and small commercial applicators.   The TMDL report concluded that it will take a 71 percent decrease in the amount of salt applied in the watershed to meet state and federal water quality standards in Shingle Creek.

 

The nine cities in the watershed, Hennepin County, and MnDOT worked together to develop an Implementation Plan to start working toward that reduction.   There is no plan to stop using road salt on icy streets.   The Implementation Plan includes activities such as using new technology such as prewetting to improve the effectiveness of road salt so less can be applied. 

The TMDL study and Implementation Plan were approved by the Environmental Protection Agency (EPA) and the Minnesota Pollution Control Agency (MPCA), respectively, on February 14, 2007. 

 

Pre-wetting Grants

 

In November 2006 the Commission received a Clean Water Legacy Act grant from the state Board of Water and Soil Resources (BWSR) to help purchase specialized equipment for snow plows.  This equipment will “pre-wet” the road salt used for de-icing, making it stick better to the road.  Because less salt will bounce off the road onto the boulevard or get blown away, less salt needs to be applied to have the same de-icing effect.  Cities in the watershed, Hennepin County, and MnDOT will all use this specialized equipment over the coming years to reduce their use of road salt.

 

The Commissions’ Education and Public Outreach Committee (EPOC) also developed a brochure called A Low Salt Diet for Shingle Creek.  It describes ways in which citizens and small commercial operators can help reduce salt use in the watershed by using Best Management Practices (BMPs) for salt application.  In the future, the Commissions will offer training to private contractors so they understand how they can use BMPs to use road salt more effectively.

 

Lake TMDLs

 

In 2003 the Commission began developing TMDLs for the thirteen lakes included on the 303(d) impaired waters list.  Impairments to the lakes have developed over time as the watersheds draining to them have been urbanized.  As undeveloped land has been converted to urban and suburban uses, the volume of runoff has increased and, along with it, the amount of pollutants, slowly degrading the lakes.  Improvement will also take many years through ongoing retrofit of the lakesheds with Best Management Practices (BMPs) as well as eventual redevelopment of existing land uses with lower-impact development and stormwater treatment.

 

Twin Lakes/Ryan Lake TMDL

 

The Twin Lake chain of lakes is located in the cities of Brooklyn Center, Crystal, Minneapolis and Robbinsdale.  They are highly-used recreational water bodies that support fishing and swimming as well as provide aesthetic values.  The drainage area to the lake chain is 5,550 acres of fully developed urban and suburban land.  Connected by channels of varying lengths, the lake system discharges into Shingle Creek, which ultimately discharges into the Mississippi River.  Water quality in Upper and Lower Twin Lakes is considered poor with frequent algal blooms while Ryan and Middle Twin Lakes have more moderately degraded water quality.  Upper and Lower Twin Lakes do not currently support recreational activities while Ryan and Middle Twin Lakes partially support recreational activities.

 

A spring aquatic vegetation survey conducted for Upper, Middle and Lower Twin Lakes and Ryan Lake showed that the Twin Lake chain had extensive coverage of both Eurasian water milfoil and curly-leaf pondweed.  The greatest diversity of species was found in Ryan Lake with seven native species.  Curly-leaf pondweed was also present in the lake.  These results demonstrate there is little diversity in the Twin Lake chain and two problematic invasive species are present.  Results also indicate that the shallow basins, Upper and Lower Twin Lakes, are currently in a turbid water state.

 

Based on the current State narrative standard for nutrients, the TMDL establishes a numeric target of 40ug/L total phosphorus concentration for all lakes in the North Central Hardwood Forest ecoregion.  Upper Twin contributes a substantial load downstream to the other lakes, thus improvements to that lake should result in improvement to the lower lakes in the chain.  DNR wetland 639W, just upstream of the lake, was found in a previous study to export a significant phosphorus load.  Improvements to wetland 639W, internal load management, and reduction of nonpoint sources of phosphorus in the watershed by retrofitting BMPs would have the most impact on reducing phosphorus load and improving water quality in the chain of lakes.  The Twin Lakes/Ryan Lake TMDL was approved by the EPA on November 9, 2007.  It may be viewed at http://www.pca.state.mn.us/water/tmdl/project-twinryan.html.

 

Concurrently with the TMDL, the Commission’s Technical Advisory Committee developed the Twin Lakes/Ryan Lake TMDL Implementation Plan.  Activities identified as most effective in restoring water quality to the chain of lakes include:

 

·         Treatment Options such as street reconstruction and

 development/redevelopment projects

·         Wetland 639W Restoration

·         Increased Infiltration

·         Shoreline Management and Restoration

·         Wildlife Management

·         Street Sweeping

·         Road Salt Reductions

·         Chemical Treatment

·         Lake Drawdown

·         Aquatic Plant Management

·         Rough Fish Management

 

The Twin Lakes/Ryan Lake TMDL Implementation Plan was approved by the MPCA on November 13, 2007.

 

Shallow Lake Ecology

 

A new section has been added to the website addressing the unique ecology of Shallow Lakes. It may be found under the “Lakes” heading in the menu along the left hand side of this page.

 

 

Dissolved Oxygen TMDL

 

In 2004 the Commission began working with the MPCA to develop a work plan for a Dissolved Oxygen (DO) TMDL.  DO problems are likely caused by a combination of nonpoint source (NPS) discharges, point source stormwater discharges, natural organic matter contributions by wetlands through which the creek flows and by ditching and other physical alterations to the channel.  Inflow of groundwater with low DO concentrations in combination with limited re-aeration may also contribute to the problem.

 

Phase one of the work plan consists of data collection and monitoring. 

 

The second phase will include modeling and load development.

 

The third phase will involve remedial actions/projects.

 

Work began in early spring 2007.

 

Biotic Integrity TMDL

 

Since Shingle Creek had also been added to the impaired waters list for biota integrity in 2006 the MPCA approached the Commission to develop the biotic and DO TMDLs concurrently.

 

Shingle Creek was listed for Biotic Impairment based on the Macroinvertebrate Index of Biotic Integrity (M-IBI), Bass Creek based on the fish IBI. (An IBI is a tool to quantify and assess the health of the biological community; however, it does not identify the cause of the impairment.)

 

Developing the TMDLs together provides an economy of scale since a likely biotic stressor is low dissolved oxygen.  However, dissolved oxygen is only one potential stressor – excess chlorides, poor habitat, flow velocities, sedimentation and other urban stormwater runoff pollutants may be others.  The Commission will use causal analysis to identify the most probably cause of impairment from a larger set of candidate causes.  The outcome will be a document detailing the selection of the probably causes for the biological communities in Shingle and Bass Creeks.

 

Concurrently with DO TMDL, load allocations will be developed for those stressors identified in the causal analysis.  Stakeholders, regulatory agencies and the Commission will then come together to address issues and concerns in order to define desired outcomes and develop implementation strategies.  Work on the combined DO/Biotic TMDL is anticipated to be completed by June 2009. 

 

 

 

Shingle Creek Corridor Study

 

In 2003, the Shingle Creek Watershed Commission undertook a comprehensive assessment of Shingle Creek and its tributary Ryan Creek for the purpose of developing a coordinated vision for the future of Shingle Creek and its tributaries.  Click the Shingle Creek link on the left side of this page to view the study’s final report.

 

Stream Assessment, Phase II

 

In the second phase of the Stream Assessment, Bass, Eagle, Pike and Twin Creeks in the Shingle Creek watershed and Oxbow Creek and Mattson Brook in the West Mississippi watershed were evaluated.  Initiated in 2006, the bulk of the work consisted of field assessment of the estimated 11.8 miles of Phase II streams.

 

The Stream Visual Assessment tool focused on near-stream and streambank and rated each reference site using a standard scoring system for:

 

            - Channel Condition                  - Water Appearance                 - Instream Fish cover

            - Hydrologic alteration - Nutrient enrichment              - Barriers to fish movement

            - Riparian zone width                - Manure presence                    - Riffle quality

            - Bank stability             - Salinity                                  - Invertebrate habitat

            - Canopy Cover                          - Pools

 

The EPA’s Rapid Bioassessment Protocol focused on habitat and stream structure.  Together these assessment tools allowed for quantification of stream conditions and served as a baseline for monitoring change and documenting future improvement.

 

The final report will be used by the Commissions and member cities to develop management activities and prioritize and complete specific capital improvements as well as to provide guidance when development and redevelopment provide opportunities to incorporate environmental amenities.

 

Local Water Quality Projects

 

Implementation of water resources management takes place at the local level.  The scale and nature of activity in the cities within the watersheds vary from city to city and from year to year based on their unique circumstances: developing, fully developed, or redeveloping; emphasis on private projects vs. regional public projects; and fiscal capacity.

 

Cities actively reconstructing streets and utilities have unique opportunities to retrofit existing systems with ponds or other facilities on a very cost-effective basis.  Some cities in the Shingle Creek and West Mississippi watersheds are currently actively constructing or reconstructing infrastructure.  Others have completed a cycle of construction or reconstruction and are currently in the mode of maintaining their systems.  Some actively developing cities require private developers to construct all infrastructure improvements and thus may not need to construct public improvement projects.  All of these activities are consistent with the overall water resource goals of the commissions.

 

Cities also routinely perform maintenance BMPs (Best Management Practices) such as routine street sweeping, catchbasin and storm sewer cleaning and maintenance of outfalls and ponds.  These maintenance activities not only protect a city's investment in infrastructure and improve water quality, they can reduce private property damage during extreme runoff events by maximizing storm water storage and flow.

 

All cities enforce the Commissions’ requirements regarding water detention and treatment. All private development exceeding certain size requirements must provide detention and treatment on site or demonstrate that adequate detention and treatment is available in a regional or other facility.

 

In addition, all private developers must meet the Commission’s erosion control requirements.  Each project is reviewed by the Commissions and includes water control features to ensure the water management goals of the Commissions are met.  Almost all the cities have constructed numerous public and/or private facilities that control runoff and treat stormwater. These have a beneficial effect on the quality of surface waters, substantially reducing pollutants. However, additional projects have been completed or are contemplated specifically to provide benefits to lakes or to Shingle Creek itself.