Projects by Type:
Hydrologic/Hydraulic | Natural Resource Management | Monitoring
Hydrologic/Hydraulic
Central Draw Overflow
The East Ravine subwatershed incorporates the preferred path for the Northern subwatershed overflow to provide an outlet to the Mississippi River. The Central Draw Overflow Project is intended to provide principal and emergency outlet capacity for this land locked watershed under existing conditions. The Central Draw Project is comprised of two phases. The first phase of improvements provides downstream capacity up through completion of Woodbury’s Phase I AUAR development area. The second phase of improvements will provide downstream capacity through storage as well as a principal and emergency outlet for full development through 2020.
Right-of-way acquisition began in September 2012. HDR Engineering has submitted the 60% set of plans to Washington County and SWWD. A cost estimate for these plans has been done. The Environmental Assessment Worksheet has been updated and finalized
HWY 61 Corridor Stormwater Retrofit Assessment
Retrofit analysis completed in 2009, served as model for extensive retrofit analyses throughout the Twin Cities metropolitan area. Analysis identified the 10 most cost effective commercial retrofit opportunities in the corridor to remove decrease phosphorus loading to the Mississippi River. Implementation relies on completely voluntary public/private partnerships between SWWD and each commercial landowner. To date, two sites have undergone retrofit, resulting in the removal of approximately 12 lbs of phosphorus from the drainage system. Outreach efforts with the remaining commercial properties are ongoing.
The HWY 61 Corridor Assessment Report
Central Draw Storage Facility (CDSF) Outlet Connection and Central Ravine Improvements
In cooperation with the City of Cottage Grove the SWWD has developed a low flow outlet connection to the Central Ravine for the CDSF area. The purpose of this connection will provide a limited capacity outlet for the CDSF and make water quality and emergency overflow improvements to the Central Ravine at 80th Street. The limited capacity outlet will allow local drainage to be evacuated from the CDSF prior to regional flows arrive at the facility. Improvements to ponding areas south of Kingston Park include water quality improvements and rate control improvements along with the installation of an emergency overflow that eliminates potential flood water on 80th Street.
The City of Cottage Grove awarded the contract in September 2012. The work to extend the low flow outlet from the pond on the north side of 80th Street to the south side is complete. The project is multi-purpose and will provide emergency overflow, rate control, water quality improvements and park enhancements.
Total Cost $1,147,518.00
SWWD $1,063,000.00
City of Cottage Grove $87,000.00
Total Phosphorus removed 106lb/yr
Newport Ravine
A ravine located in Newport near Interstate 494 and Military Road has been receiving stormwater discharges. Erosion in this ravine has been a problem and attempts have been made to remedy the situation. Large storms in October 2005 resulted in erosion in excess 500 cubic yards of sand, flooding of residences along and at the bottom of the ravine, flooding of roadways at the bottom of the ravine, and discharge of stormwater into the sanitary sewer system. The City of Newport conducted an investigation into the 2005 event and examined possible solutions to prevent recurrence in the future. Hydrologic analysis indicated that flow velocities during major rain events are well in excess of acceptable velocities for sandy composition of the soil in and around the ravine. The City of Newport has developed a plan to address issues encountered during the 2005 event. The plan will be carried out in two phases. Phase I will include armoring the ravine channel, installation of check dams, and bluff repair and stabilization. Phase II will utilize biofiltration and pretreatment sedimentation basins at the top of the ravine to reduce peak flows. The City of Newport in cooperation with the District has completed a feasibility report for construction of the ravine stabilization project (see attached report, City of Newport, MN North Ravine Stormwater Project Plan dated April 6, 2009, BDM Consulting Engineers and Surveyors, PLC) Phase II of the proposed project is conceptual, final design will be completed by the District. The District may become involved in the implementation of Phase I at a future date should the City of Newport request assistance.
Project complete
Total Project Cost $2,395,000.00
SWWD $1,676,000.00
City of Newport $20,000.00
Grant Dollars $699,000.00
Total Phosphorous Removed 11lb/yr
Total Sediment Removed 650 tons
Washington County Road 19-20-22 Realignment Project
As early as 1979 and 1980 the Cities of Cottage Grove and Woodbury contemplated a connected stormsewer system between the Northern watershed and south through Cottage Grove to the Mississippi River. Since the establishment of the SWWD in 1993 and the creation of the first watershed management plan in 1997 the SWWD has been evaluating and planning for the construction of a watershed overflow. Between 2000 and 2004 the SWWD contemplated a combined project with the Metropolitan Council during the construction of the South Washington County Sanitary Sewer Interceptor. At that time the SWWD determined that other partnerships would be available in the future for the SWWD to pursue a combined project and decided not to enter into a partnership with the Metropolitan Council.
In 2011 Washington County included in the County Capital Improvement Plan, a safety and mobility project for County State Aid Highways #19, 20, and 22 in Cottage Grove. This has provided an opportunity for the SWWD to begin construction of the watershed overflow within the County Road corridor. In cooperation with Washington County and the City of Cottage Grove the SWWD is designing the first phase of the overflow project. Pending development in the City of Woodbury Phase II, the City of Cottage Groves East Ravine Neighborhood I development and the Washington County road project creates the need for the SWWD to begin construction of the overflow.
The SWWD is planning to construct the overflow through Cottage Groves East Ravine Neighborhood II over a 4-6 year timeframe. Construction of the first phase will begin in 2013. This project also provides a unique opportunity for separate units of government to consolidate efforts to maximize efficient and effective use of resources. South Washington Watershed District (SWWD) has identified a regional drainage need in the area of the new alignment. The Central Draw Overflow.
Schedule
| April 10, 2012 | Open House #1 |
| Fall 2012 | Complete Plan Preparation |
| Spring 2013 | Begin Construction |
| Fall 2013 | Complete Construction |
Clear Channel Pond
Clear Channel Pond is situated in Cottage Grove. If the pond experiences flood conditions the overflow spills into St. Paul Park thereby presenting an inter-community flow issue. In order to protect the adjacent railroad tracks, modeling by Cottage Grove suggests the need to maintain the existing overland flow route from Cottage Grove into St. Paul Park during major events. Many parties are involved in the dialogue to find a solution. One proposed solution is to construct a lift station for Clear Channel Pond that would discharge to Hamlet Park Pond which is already experiencing water level issues (see section 3.2.4.3). A second, and preferred, solution is to expand stormwater storage in the area that would serve to relieve Clear Channel Pond, help protect infrastructure, and reduce flooding from inter-community flows. At this time, efforts will focus on the second solution, which is more cost-effective. To move forward with the Clear Channel Pond relief project in three phases. First, SWWD, Washington County and Cottage Grove will purchase the former Wheels of Travel property adjacent to Clear Channel Pond. Second, a study will be conducted to examine options to increase storage and design a storage facility. Finally, the stormwater storage facility will be constructed.
Grey Cloud Island Slough Restoration
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.
Grey Cloud Island Feasibility Report May 2012
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.
TMDL Retrofit Analysis Phasing Map
2013 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.
Natural Resource Management
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. In 2007, the SWWD planted trees and established upland grasses along the west property line. In 2008, the restoration continues with additional tree and seed planting and prairie maintenance. This will add approximately an additional five acres to the restoration area.
In 2010 the SWWD received a grant from Great River Greening for restoration of native prairie in the area of the Regional Infiltration Basins. The goal of this project is to restore this area according to the management plan developed for the conservation easements placed on the property with the Minnesota Department of Natural Resources and Washington County. Historically this landscape would have consisted of primarily Oak Savannah with interspersed pockets of wet prairie. A majority of this area, those above the high water mark and on the steep slopes will be managed for Oak Savannah, low areas will be managed for wet prairie. Future management of the area will be high dependent on the frequency of stormwater presence.
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.
Trout Brook Restoration
The Trout Brook subwatershed was transferred to SWWD in 2010 and makes up roughly 8% (5530 acres) of the District. Trout Brook was previously identified as one of the highest priority surface water resources in the former Lower St. Croix Watershed Management Organization. The stream itself is groundwater supported and provides habitat and water temperatures suitable for trout, although it is not currently known to do so.
The Trout Brook was a priority subwatershed for the former Lower St. Croix Watershed Management Organization and remains so for the SWWD. Increased development within the Trout Brook subwatershed has the potential to increase flow, water temperature, and nutrient concentrations within the stream. Efforts are necessary to protect the stream for existing aquatic communities and potential future trout populations. The former Lower St. Croix Watershed Management Organization initiated development of the Trout Book Management Plan to study and address concerns in the Trout Brook subwatershed. SWWD will continue to manage the Trout Brook subwatershed as called for in the “Management & Improvement Recommendations” section of the completed plan.
A significant portion of Trout Brook flows through the Afton Alps ski area at the base of the ski slopes. As part of its efforts to restore Trout Brook, SWWD is currently working with Afton Alps through a public-private partnership to implement improvements within their property. Those efforts will include in-stream habitat restoration, bank stabilization, and installation of BMPs throughout the property which will reduce erosive flows and help reduce nutrient loading to both Trout Brook and Lake St. Croix. Future efforts will focus on improvements within the Afton Alps State Park.
Watershed Restoration
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.
Monitoring
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.
2005-2006 Frost/Snow Monitoring Report
Projects by Type:
Hydrologic/Hydraulic | Natural Resource Management | Monitoring