JD2 Project Team

Judicial Ditch 2 Sediment Retention Ponds

Situated just west of Lake Osakis, the Judicial Ditch #2 (JD2) sediment retention ponds were constructed between 2002 and 2004. They are owned and operated by the Sauk River Watershed District (SRWD). The project was undertaken in an effort to address the sedimentation issues in Lake Osakis. The SRWD received a demonstration grant from the Board of Water & Soil Resources (BWSR) in 2001 to install the project. It is a 2-pond system that is situated off of the main channel of JD2 in Douglas and Todd Counties.

JD2, also referred to as Crooked Lake Ditch, is a legal drainage system that drains a large portion of the historic Crooked Lake area and outlets into Lake Osakis. Crooked Lake was a 2200-acre shallow basin that once supported a diverse aquatic community. This basin was drained in the early 1900s to be converted to cropland, which is effectively the function of JD2. The land that drains to JD2 accounts for about 30 percent of Lake Osakis’s watershed, carrying sediment and nutrients from the ditch to the lake. The design of the sediment ponds, which diverts the flow of JD2 into the ponds, allows these sediments and nutrients to settle out of the water column. It includes an initial small, deep pond and a large, shallow secondary pond. The primary pond is 0.75 acres and deeper, while the secondary pond is 10 acres and shallow. Water flows through the system and eventually enters back into the ditch before reaching Miller Bay, which is about a mile south of the sediment ponds.

This project is estimated to have a sediment reduction rate of 50 percent and a particulate phosphorus reduction rate of between 20 and 30 percent. According to the Osakis Lake Area Total Maximum Daily Load (TMDL) study completed in 2012, JD2 carries approximately 3,800 pounds of phosphorus to Lake Osakis per year. So, how have the ponds been doing at reducing sediment and nutrients in the system? There have been 3 cleanouts of the ponds since their construction. The 2009 cleanout removed 750 tons of sediment from the primary pond. Another cleanout in 2012 removed 757.5 tons of sediment from the primary pond. The most recent one in 2019 removed 22,000 tons of sediment (that’s about 1,769 dump truck loads) from the secondary pond. That means around 23,507.5 tons of sediment were prevented from entering Lake Osakis.

Design Plan

Project Timeline (click to enlarge)