NE St. Cloud Water Quality Improvements
Background & Concerns
The Northeast St. Cloud area consists of 367 acres where stormwater runoff drains into the Mississippi River primarily through a 96" outfall pipe. About 50% of the area is industrial and commercial land uses. Before the Northeast Water Quality Improvement Plan was implemented, stormwater runoff drained directly to the Mississippi River untreated. This is the same pool of the river where the city draws its drinking water. Prior to stormwater improvements, approximately 136,000 pounds of sediment entered the river annually through this one storm drain system.
Northeast St. Cloud is an older part of town developed prior to current land use and water quality standards. In 2009, citizens and City staff began noticing "brown water" entering the Mississippi River from a stormwater outfall. The combination of industrial/commercial land uses, gravel surfaces, minimal green space and no stormwater treatment was contributing to the sediment plume. The City began a partnership with Benton Soil and Water Conservation District and property owners to reduce pollutants entering the Mississippi River from this drainage area.
*Picture of Sediment plume from the 96" outfall that drains a majority of the NE drainage area*
Implementation Plan & Timeline
To begin addressing the pollution problem, a detailed assessment of the northeast area was conducted which included an analysis of drainage patterns, land use, pollutant runoff estimates, inspections, evaluation of solutions, and a prioritized implementation plan.
The City worked with a local water resource consultant, SEH, to assemble the NE Drainage Analysis Report. The implementation plan was updated in 2018 and again in 2025. The implementation plan guides staff to execute inspections, education and enforcement, and positions the City for funding to implement water quality improvement projects.
Timeline
Goal: 70% Sediment Reduction by the year 2029.
2012
NE data analysis complete. Enforcement and education begins.
2014
NE projects designed. Applied for funding.
2015
Clean water grant funding received.
2016
6 projects completed. Estimated 12.2 tons/yr sediment reduction achieved.
2018
NE implementation plan updated.
2019
BWSR grant awarded for 2 underground regional stormwater treatment systems. Estimated 9.7 ton/yr sediment reduction. 35% of goal achieved to date. Grant application applied for a new sediment reduction project.
2023
Underground regional treatment system #4 Installed.
Education & Enforcement
Public education and encouraging good stormwater management behavior is essential to meet water quality goals. Part of the northeast water quality improvement plan is to increase public education efforts and the level of inspections/ordinance enforcement in the area. With help from property owners and businesses, water quality improvements can be maximized.
Targeted education and inspections/enforcement implementation began in 2010. Inspections and enforcement of the City's Stormwater System Use Code is key in improving water quality.
A Lunch and Learn event was held for area property owners and businesses to share ideas, learn about the water quality issues and improvement projects.
Sediment Reduction Projects
Regenerative Air Street Sweeper
The City partnered with Benton SWCD in 2015 to purchase a regenerative air style street sweeper using a BWSR Clean Water Legacy Grant through the Board of Water and Soil Resources. The regenerative air sweeper uses high velocity air to dislodge sediment and debris from the road surface. The sweeper is used as part of the enhanced, prioritized northeast area street sweeping plan.
Annually, the enhanced street sweeping removes an estimated:
- 12,000 lbs. of sediment
- 5 lbs. of phosphorous
Sumps
Sumps are structures with low spots in the storm drainpipe system to collect and contain sediment and debris. Added baffles and weirs dissipate energy allowing more sediment and floatable trash to be trapped in the sump and not washed to the river. Sumps are cleaned 2-3 times a year using a vacuum truck. Four sumps were installed in the northeast area in 2015 using a Clean Water Legacy Grant in partnership with Benton SWCD.
Annually, sumps divert an estimated:
- 1,500 lbs. of sediment
- 2.2 lbs. of phosphorous
East Germain Parking Lot Rain Garden
In 2016, an eroding gravel parking lot was paved, and a rain garden was installed to filter runoff from the lot and adjacent street. The rain garden keeps pollutants out of the river while providing habitat for bees, birds, and butterflies. The paved lot provides parking for area businesses. The project was partially funded using a Clean Water Partnership Grant through the Minnesota Pollution Control Agency (MPCA).
Annually, the East Germain Parking Lot Rain Garden diverts an estimated:
- 600 lbs. of sediment
- 0.4 lbs. of phosphorous
- 125,000 gallons treated
Green Right-of-Way
In 2016, over one acre of paved and gravel surfaces in the City’s right-of-way was replaced with grass & trees using a Clean Water Partnership Grant. Runoff from over six acres of land is filtered by flowing through the new vegetation before entering the street and storm drain system. Not only does this project contribute to improved stormwater quality, but it also enhances and beautifies this heavily developed part of town by adding green space and 62 trees.
Annually, the green right-of-way diverts an estimated:
- 4,200 lbs. of sediment
- 10.1 lbs. of phosphorous
- 2,500,000 gallons treated
Regional Treatment Systems
Regional underground stormwater treatment systems act like underground ponds, maintaining a 4-foot ponding depth in the pipe. The systems utilize several baffles and weirs to contain floatables and allow solids to settle and be contained in the pipe, reducing the amount of sediment discharged to the Mississippi River. Four regional treatment systems have been installed in the northeast area.
Regional Treatment System #1
Using a Clean Water Legacy Grant in 2016, the City partnered with Benton SWCD and the businesses of MN Structural Steel and Ferguson, to install an underground stormwater treatment system under 4th Street NE. The system consists of three 160 foot rows of 11’ diameter CMP pipe with over 17,700 cubic feet of water storage capacity. The system treats 45 acres of stormwater runoff and captures 5.2 tons of sediment annually from the Lincoln Avenue NE area, which is 10.2% of the sediment reduction goal.
Annually, regional treatment system #1 diverts an estimated:
- 10,200 lbs. of sediment
- 19.7 lbs. of phosphorous
- 14,500,000 gallons treated
Sediment accumulation prior to cleaning
Regional Treatment Systems #2 & #3
In 2019, using funds from a Clean Water Legacy Grant, two regional treatment systems were installed in partnership with a neighborhood redevelopment project. These treatment systems have over 16,000 cubic feet of water storage capacity, treating 35 acres of stormwater runoff, and removes 4.5 tons of sediment annually, or 9.2% of the sediment reduction goal for the northeast area.
Annually, these two regional treatment systems divert an estimated:
- 9,220 lbs. of sediment
- 14.4 lbs. of phosphorous
- 13,400,000 gallons treated
Regional Treatment System #4
In January of 2020, the City received a Clean Water grant to install another underground regional stormwater treatment system near Simonson Lumber. This treatment system has over 13,000 cubic feet of water storage capacity, treating 19.6 acres of stormwater runoff that previously drained directly to the Mississippi River untreated. This system removes 2.2 tons of sediment annually or 4.4% of the sediment reduction goal for the northeast area.
Annually, this regional treatment system diverts an estimated:
- 4,373 lbs. of sediment
- 10.7 lbs. of phosphorous
- 5,600,000 gallons treated
Water Quality Improvements
There have been seven completed grant funded projects since 2015 and numerous other City and private water quality treatment practices installed. An estimated 51% of the desired 70% sediment reduction goals has been achieved. Additional implementation, strong partnerships, and continued grant funding will be needed to achieve the rest of the goal.
Estimates based on modeled pollutant reductions for stormwater treatment practices implemented.
Visual inspections of the Northeast drainage area outfall have shown improvements as shown by the photo comparison below. These improvements demonstrate significant progress in water quality improvement. However, it is important to recognize that there remains work to be done in order to fully achieve the target of a 70% sediment reduction. Continued efforts are necessary to ensure that this goal is met, and further improvements are realized in both the efficiency and effectiveness of the drainage system.
2009 (left) vs 2020 (right) Visual inspection comparison of similar rain events showing a greatly reduced sediment plume.
Project Partners
For additional information, check out the links below:
Contact Us:
stormwater@ci.stcloud.mn.us (320) 255-7226 ci.stcloud.mn.us/1868
