Central Draw Overflow
One of the primary reasons SWWD was formed was to identify, design and construct an outlet for the District’s northern watersheds which include one of the fastest growing communities in the State. At the time, runoff from the northern watersheds collected at Bailey Lake which had no controlled outlet. Communities in the District recognized that Bailey Lake would not be adequate to contain all of the runoff from the watershed when it was fully developed. Since that time, SWWD and its partners have been working to construct the Central Draw Storage Facility (CDSF), which includes 1800 acre feet of storage on 250 acres near the outlet of Bailey Lake. A City of Woodbury lift station now pumps water from Bailey Lake to the CDSF. With the size of the CDSF and rate/volume restrictions on development draining to Bailey Lake, the system should be adequate to retain the runoff for a 6.3”, 24 hour rainfall event. However, because of uncertainty in design, recent trend of extreme precipitation events and degree of safety necessary for flooding situations, SWWD is in the process of constructing a controlled overflow out of the CDSF to the Mississippi River. The project is being implemented in 5 phases. Phases I (pipe connection under CSAH 19) and II (stream stabilization between Ravine Lake and Mississippi River) are complete.
Overflow Phase III (Ravine Lake Outlet) and Phase IV (Upper East Ravine Stabilization) –SWWD is currently working with Washington County staff, and their consultants, on the Cottage Grove Ravine Regional Park Master Plan Amendment to incorporate plans for phases III and IV. SWWD and County Parks staff have reached consensus on a stabilization concept. That concept will be included in the Master Plan. Additionally, an updated tree survey has been completed which will be used to quantify impacts from construction and potential inundation during an overflow event. Invasive species removal (pending approval) will commence in February 2016 on approximately half of the ravine corridor (20 acres) to make the ravine corridor more resilient through native groundcover regeneration.
Design of the lake outlet is also underway. The outlet will be built as part of the County’s CSAH 19/park entrance project. SWWD is working with Washington County on the design of that project. For more project details visit the Washington County website: County Highway 19 (Innovation Rd) in Cottage Grove
Grey Cloud Island Slough Restoration
Background-The Grey Cloud Slough is located east of the main channel of the Mississippi River, near the boundary between Grey Cloud Township and St. Paul Park. Although described as a “slough” this 2.8 mile long waterbody is a “cut-off” meander loop of the Mississippi River. The mouth of the meander begins at Mississippi River Mile (RM) 827.6 and ends at the confluence of a larger backwater portion of the River immediately north of Grey Cloud Island.
Ecological functions and services provided by the meander are diminished, in part, because of the loss of longitudinal connectivity with the Mississippi River. Water no longer flows through the meander due to blockage of the culverts under the roadway at the mouth of the meander. Restoration of the ecological functions and services historically provided by the Grey Cloud Slough as a meander of the Mississippi River is a priority for many local, state, and federal agencies.
SWWD is providing local leadership for this project by completing a feasibility study for restoring ecological functions and services. Working with its consultants and a Technical Advisory Committee made up of various local, state, and federal agency representatives, SWWD will identify a preferred solution to restoring connectivity with the Mississippi River. With a preferred solution identified, SWWD will work to develop partnerships with other agencies and secure funding to implement the project.
Background-SWWD secured a FY 2012 Clean Water Fund grant for installation of priority BMP’s throughout the Trout Brook watershed which were identified through the WCD’s Top50P! project. All Projects are complete.
Background–SWWD has completed a retrofit scoping/feasibility study for the Afton Alps ski area. The study identifies several options for restoring habitat in Trout Brook and reducing sediment and phosphorus export to Trout Brook and Lake St. Croix. After reviewing the plan, MnDNR is engaged and excited to develop a partnership with SWWD and Afton Alps Ski Area and pursue a larger scale stream restoration project than SWWD would be able to accomplish on its own.
SWWD is working to develop a stream restoration project within Afton Alps ski area. SWWD, MnDNR, Afton Alps (Vail), and Great River Greening have developed a proposal which was included as part of the Metro Big Rivers (MBR) proposal to Lessard Sams for FY2017. The Lessard Sams council has recommended partial funding for the MBR partnership which will include the full request (~$700,000) for the Trout Brook project. Funds will be allocated by the legislature in the 2016 session. Following fund allocation, design will begin and carry through winter 2016/2017. Construction is expected to follow the end of ski season in the spring of 2017.
City of Woodbury Roadway Reconstruction Coordination
SWWD secured a Clean Water Fund grant to fund Best Management Practices as part of the City of Woodbury’s 2016 road rehabilitation project. That work will include 6 residential raingardens, a large public raingarden, and retrofit of an existing stormwater pond adjacent to Wilmes Lake to include iron enhanced sand filtration. SWWD will lead the design and construction of the residential raingardens. The City will lead the construction of the large public raingarden and stormwater pond retrofit.
2016 Clean Water Cost Share Program
Opportunities for regional water quality improvement projects are limited and difficult to coordinate. Opportunities for smaller projects, however, exist on every residential, municipal, and commercial property. The South Washington Watershed District (SWWD) Clean Water Cost Share Program offers financial assistance to encourage and enable citizens, municipalities, and businesses to use innovative practices to protect and improve lakes and streams within the district. This program promotes water quality improvement by focusing on the reduction of phosphorus in stormwater runoff. Each pound of phosphorus, a nutrient critical to algae growth, removed from stormwater runoff can prevent up to 500 pounds of algae in our lakes, streams, and rivers.
SWWD worked with the City of Newport, MnDOT, and MPCA to fix excessive ravine erosion on the bluff overlooking the historic Mississippi River terrace in Newport. Local runoff rates far exceeded the capacity of the existing drainage system which was characterized by highly erodible sandy soil and limited vegetation. SWWD and its partners utilized several practices to reduce flow rates into the drainage system and increase stability of the ravine.
SWWD Water Quality Work
SWWD continues to work on a watershed-wide water quality management program. Work is progressing on a subwatershed basis and resulting load allocations are subwatershed specific. The program involves five phases:
-Monitoring and watershed and in-lake water quality modeling
-Load allocation based on SWWD water quality goals, MN water quality standards, and future Mississippi River or St. Croix River TMDL requirements
-Subwatershed retrofit analysis, in cooperation with local municipalities, prioritizing BMPs to meet load allocations based on cost-effectiveness
-Implementation of projects identified in retrofit analysis using existing SWWD Cost Share, CCIP, and water quality implementation funds and existing municipal implementation funding
-Monitoring to confirm water quality improvements projected in retrofit analysis
The watershed-wide water quality management program draws from and coordinates current SWWD and WCD efforts and programs to achieve water quality goals set in the SWWD watershed management plan, fulfill TMDL requirements for impaired waters within the district, and meet load allocations from future Mississippi River and St. Croix River TMDLs. Currently SWWD has completed the Powers Lake allocation and is working with the WCD to complete the subwatershed retrofit analysis. In 2011, SWWD will work on an allocation and retrofit analysis for the Central Ravine subwatershed and increase monitoring activity around Colby Lake to collect data necessary to complete an allocation on 2012. Below is a phasing map.
CD P85 Restoration
In preparation of development in the southern portions of Woodbury and northern portions of Cottage Grove (East Ravine) the SWWD began restoration of the CD P85/86 greenway corridor. Several white oak trees were recently planted at the prairie as part of a research project. Two distinct ecotypes were used—northern and southern. Growth and health of the two ecotypes will be used to study migration associated with changing climates. The management focus for the site will strongly shift to maintenance in 2016. Activities will include a burn, ongoing haying (as grazing surrogate), and another volunteer event which will focus on enhancing existing restoration plots with additional wildflowers.
Powers Lake Protection
Historically Powers Lake was a land locked basin that exhibited fluctuations in water levels over time. Through development of the Woodbury East Alternative Urban Areawide Review the drainage area of Powers Lake was increased. During development of the watershed the SWWD worked with the City of Woodbury to incorporate infiltration practices into the construction of stormwater management facilities throughout the Powers Lake watershed.
With stormwater controls in place through development the lake water quality continues to trend downward. The SWWD in cooperation with the City of Woodbury and the Washington Conservation District have begun to implement retrofit projects to increase the protection of the lake. Additional actions will be necessary to address high internal loading
Chain of Lakes Restoration
The paradigm of stormwater management in the United States has shifted focus from primarily flood control to improving water quality. This shift is the result of implementation of water quality requirements of the Clean Water Act (CWA) of 1972. The CWA prohibits the discharge of pollutants from point sources to waters of the United States. This was accomplished through the development of a permit system known as the National Pollutant Discharge Elimination System (NPDES). While this regulatory mechanism has largely addressed point discharges (i.e. pipes or man-made ditches) a large source of pollutants still exists in non-point sources. Non-point sources are those that are not collected in a point source rather run off the land in the form of nutrients, chemicals and bacteria.
The SWWD has embarked on a program to systematically inventory, assess, analyze and identify sources and corrective actions that will minimize the delivery of non-point source pollution to the rivers, streams lakes and wetlands of the watershed. The goal of the program is to achieve the recommended pollutant reduction that results in water quality improvement through the most cost efficient means.
Beginning in 2009 the SWWD is analyzing each sub-watershed area of the watershed and identifying “hot spots” of pollution. Concurrent with this analysis is an inventory of potential projects to reduce the delivery of pollution to a particular water body. The result is a list of projects, timetable for implementation and an estimate cost of the project to achieve a quantifiable reduction goal. The SWWD then works with residents, commercial properties, institutions, developers, Cities and the County to implement the projects through various mechanisms. To date, assessments have been completed for the Powers and Colby Lake sub-watersheds and implementation is underway. Assessments for Armstrong, Markgrafs, and Wilmes Lakes will be completed in 2012/2013. Remaining SWWD sub-watersheds will follow.
The St. Croix and Trout Brook subwatersheds were transferred to SWWD in 2010 and make up roughly 10% (7130 acres) and 8% (5530 acres) of the District. These basins drain directly to Lake St. Croix of the Lower St. Croix River which is designated as an Outstanding Resource Value Water (ORVW) and currently listed as impaired for excess nutrients.
The St. Croix River is an important resource both locally and regionally. Currently listed as impaired, a TMDL study is underway to address excess nutrient loading. The District will cooperate with the ongoing study and work with municipalities and Washington County to implement water quality improvement projects in an effort to achieve load reductions identified in the TMDL study.
Several erosion areas have been identified along both Trout Brook and the St. Croix River and it is likely that other eroded or erosion prone areas exist. These areas contribute to ongoing degradation of the St. Croix River and will be addressed as part of implementing load reductions expected to be required as part of the St. Croix River TMDL.
Currently, SWWD is participating in two coordinated efforts to address identified issues. First, SWWD is working with the Washington Conservation District (WCD) to identify and address the biggest sources of phosphorus in the watershed through WCD’s Top50P! project. Second, SWWD has secured a State Clean Water Assistance grant to address additional sites identified as part of the Top50P! assessment.
Watershed Monitoring Reports-Washington Conservation District (WCD)
These documents contain a summary of methods and results for various surface water monitoring efforts by the Washington Conservation District (WCD). Generally, data is presented with respect to 8 lake levels, groundwater levels at 7 stations; stream flow discharge rate, volume and quality, runoff discharge rate and volume, precipitation; and, lake water quality for Armstrong and Powers Lakes. Discussion and interpretation of the results was outside the scope of the documents
Frost/Snow Monitoring Report
The South Washington Watershed District has the Washington Conservation District (WCD) conducted frost/snow monitoring at these existing frost monitoring sites (Cottage Grove Ravine Park, CDP-85 locations, CDP-86 locations, and MS-1. This report summarizes the methods and results for monitoring conducted from December 9, 2005 to March 22, 2006.