Projects by Type:
Hydrologic/Hydraulic | Natural Resource Management | Monitoring
Hydrologic/Hydraulic
Wilmes Lake Gate
The 2003 Wilmes Lake Flood Damage Reduction Report identified gated structures at Markgrafs Lake and Evergreen wetland in the City of Woodbury as part of the non-structural flood control flood management solutions. The design of the gate structures are complete. The next step in the project is to begin the bidding and construction process.
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 proposed 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.
HWY 61 Corridor Stormwater Retrofit Assessment
In 2009, the SWWD identified Highway 61 corridor commercial parcels as high priority stormwater retrofit areas given their dominant impervious land cover and for their high public outreach potential. An initial protocol for assessing commercial sites within the SWWD was developed, refined and pilot-tested by the Washington Conservation District (WCD) and Metro Conservation Districts (MCD). The protocol initially followed a series of steps using a process of elimination to determine where the greatest treatment gains are located versus overall costs, design time and project difficulty as well as other variables. The protocol was developed though a combination of professional experience of BMP retrofitting and design and with tools developed from the Center for Watershed Protection’s Urban Subwatershed Restoration Manual Series (specifically, Manual 3, Urban Stormwater Retrofit Practices; hereafter referred to as Manual 3). It was then tested and refined (in-field) and adjusted accordingly. In the summer of 2009, the pilot project was initiated assessing several dozen commercial sites that resulted in the identification of 13 high-ranking properties recommended for stormwater retrofits.
The HWY 61 Corridor Assessment report details a subwatershed stormwater retrofit assessment resulting in recommended catchments for placement of Best Management Practice (BMP) retrofits that address the goals of the Local Governing Unit (LGU) and stakeholder partners. This document should be considered as one part of an overall watershed restoration plan including educational outreach, stream repair, riparian zone management, discharge prevention, upland native plant community restoration, and pollutant source control.
The HWY 61 Corridor Assessment Report
Powers Lake Management Plan
Powers Lake is an approximately 50-acre lake located in the City of Woodbury within southern Washington County. The Watershed Management Plan (WMP) implemented by the SWWD in 2007 suggested that Powers Lake is showing evidence of water quality degradation, with increased phosphorus concentrations and decreased clarity. In an effort to prevent continued degradation of Powers Lake, the SWWD requested the assistance of Houston Engineering, Inc. to evaluate existing data and develop models that would describe the stresses imposed upon Powers Lake. This information would be used to establish a load allocation serving as the basis to improve management of the lake and its watershed. It is anticipated that the successful completion of this study will result in similar studies conducted for other important lakes in the SWWD.
This report presents an assessment of the water quality for Powers Lake including the estimated water budgets and total phosphorus mass balances for two years of monitoring. These are used along with modeling to develop a phosphorus load allocation recommendation for the Powers Lake watershed to achieve the Minnesota Pollution Control Agency (MPCA) numeric water quality standard and SWWD water quality goal for total phosphorus.
Bailey Lake/East Ravine
The SWWD is beginning to develop the design criteria for the Central Draw Overflow project that will eventually convey excess stormwater runoff from the Bailey Lake sub-watershed and upstream areas, south through CD-P85/86, through Cottage Grove East Ravine to the Mississippi River. This study has assembled all the anticipated land use changes and stormwater management plans for the City’s of Woodbury and Cottage Grove into the watershed wide model. In the end this modeling will translate to assessment points that will be used to evaluate the sub-watershed for stormwater management performance. SWWD Staff is working with the City of Cottage Grove Staff to finalize the next steps which includes updates to the Central Draw Storage Facility, preparation if design plans for the 70th Street outlet, and potential updates to the Central Ravine Model.
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 caused significant erosion and instability in this ravine. As a result, properties are threatened with damage from sedimentation. Hydrologic and hydraulic analyses are needed on a watershed basis to assess what potential solutions are available, and to determine what acceptable flow levels are to maintain stability within the ravine.
2011 Clean Water Cost Share Program
The 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. This program is available to any resident, business, or neighborhood within the SWWD boundary.
Flood Damage Reduction Program
Evaluation of the Wilmes Lake subwatershed has been conducted multiple times by the City of Woodbury and the SWWD. Following significant high water levels at Wilmes Lake (and elsewhere in the Northern subwatershed), an extensive modeling study was conducted by the District to evaluate flood mitigation options for the drainage area (Wilmes Lake Report 2006). Non-structural improvements were evaluated and presented in the Wilmes Lake Report. Five non-structural solutions were recommended for further consideration. The District’s role, along with the associated municipalities, is to continue with the ongoing and recommended non-structural solutions. The City of Woodbury, cooperatively with the SWWD, will provide flood damage reduction efforts through implementation of the flood damage reduction program for the residents of Woodbury.
Clear Channel Pond-Cottage Grove
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. A 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. The Clear Channel Pond relief project will be done 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
Following the replacement of an old bridge with an earthen dam and culverts, gradual sedimentation blocked the Grey Cloud Island Slough from Mississippi River flow. Subsequent stagnation has resulted in a significant increase in total phosphorus resulting in subsequent decline in water quality and fish populations and an increase in invasive species and algal blooms. Without action to address stagnation in the slough, water quality will continue to decline. Grey Cloud Island, working with UMN engineering students and a mentoring PE, has completed two reports. The first, “Grey Cloud Island Water Quality Project”, identified water quality problems and attributed them to decreased flow in the slough. For the project, the authors built a water quality model that they used to calculate the optimum flow rate that would reduce total phosphorus in the slough yet limit risk of bank erosion. The authors then used the calculated optimum flow rate (70 cfs) to size a replacement culvert in the earthen dam. The second report, “Grey Cloud Island Slough Crossing Project”, expanding on the first report, proposed a plan for dam and culvert replacement. The report includes design plans and cost estimates for replacing the dam and culverts designed for the 100 and 500 year flood events. Currently, SWWD and the Township plan to move forward with replacement above at the 100 year level. Work is expected to begin in summer of 2010. Completion of the project will restore flow from the Mississippi River through the Slough and improve water quality.
Grey Cloud Island Water Quality Project
Grey Cloud Island Final Report
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
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.
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