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Loretto Creek Restoration

Loretto Creek, an east tributary to Lake Sarah, is a DNR protected water and is located within the cities of Loretto and Medina.  A Total Maximum Daily Load (TMDL) study was completed and it was determined that Loretto Creek carries approximately 269 pounds of sediment and nutrients per year to Lake Sarah.  Grant money was received from the Clean Water Legacy Grant Program to provide treatment for approximately 490 acres of watershed, with the total project footprint at 2.9 acres at the Loretto ball fields.

The project includes the following main components:
  • Stabilizing the pipe outlets just west of County Road 19
  • Re-establishing 350 feet of DNR channel that was previously filled and piped
  • Constructing a small sedimentation pond to allow for routine cleaning
  • Constructing a 3/4 acre water quality pond
  • Restoring a historically filled wetland within the ball fields
  • Establishing native seed in open space areas

A water quality model was completed by Three Rivers Park District for the proposed concept plan.  The model predicts that this project will remove approximately 140 pounds of phosphorus per year.  As established in the TMDL study, the Waste Load Reduction (WLR) allocation for Loretto is 37 pounds of phosphorus per year and 247 pounds per year for Medina.  The project will slow down flows by creating more storage within the restored creek and wetland and adjacent native vegetation along with the sedimentation pond.  Flows from a 2.5 inch rainfall event will be diverted into the water quality pond and restored wetland.  This will further reduce peak flows, increase retention, and encourage infiltration and biofiltration through the use of native plants.

Funding sources for the project will consist of a combination of Medina's stormwater utility fee, City of Loretto land contributions, Pioneer-Sarah Watershed Management Commission support, and grants.  Long-term operation and maintenance needs will include verification of established wetland plants, stream channel stability, and storage capacity of the stormwater treatment system.

The project started in 2012, and the major construction and excavating is now complete.  The remaining punch list items include access roads, soil stabilization, and seeding.

Follow the link below to a document published by the Minnesota Board of Water and Soil Resources, which gives detailed information as well as photos and maps of the project.