The Lower Des Plaines Watershed Group, LDPWG, formed in 2017 as a proactive way for municipalities and other dischargers to work together to address water quality issues in the watershed. The watershed encompasses approximately 490 square miles from Willow Creek, just north of O’Hare Airport in Cook County, to the confluence with the Kankakee River in Will County. All but two municipal dischargers are participating in the LDWG. In 2018, the LDWG worked with Illinois EPA to develop special conditions language for National Pollutant Discharge Elimination
System permits that allow and encourage dischargers to work together to develop a NARP.
For more information, see www.LDPWatersheds.org.
Bioassessment Activities
The Lower Des Plaines Watershed Group coordinates a watershed bioassessment program to identify and address priority water quality issues in the Lower Des Plaines River and its 19 tributaries. The bioassessment program include sampling at 146 stations across the Lower Des Plaines River and 19 tributaries. Sampling includes water and sediment chemistry, fish, macroinvertebrates, and habitat assessments. Additional dissolved oxygen, nutrient, and chlorophyll sampling was done at a subset of sites. As a means of dividing this large scale sampling effort over multiple years, the bioassessment is conducted over a five-year cycle with one of four sub-basins sampled in a consecutive year followed by one year off: Year 1: Upper Main Stem Des Plaines River, Year 2: Lower Main Stem Des Plaines River, Year 3: Hickory Creek Sub-Watershed, Year 4: Other Major Tributaries and Year 5: No bioassessment sampling conducted. In the 2023, bioassessment sampling was conducted in the Upper Main Stem Des Plaines River and in 2024 sampling was conducted in Lower Main Stem Des Plaines River. The 2023 and 2024 sampling was the second round of bioassessment sampling for the mainstem Des Plaines River as these sub-basins were previously sampled in 2018 and 2019, respectively.
NARP Related Activities
In December 2023, the LDWG submitted their Nutrient Assessment and Reduction Plan, NARP, for all wastewater treatment plants, WWTPs, discharging to the mainstem Des Plaines River. The 2023 NARP for the non-wadeable sections of the Lower Des Plaines River included an Implementation Plan that included the following tasks:
- LDWG members shall continue active workgroup participation and funding
- Continued implementation of the bioassessment program
- Collection of additional water chemistry, biological and habitat data to develop an Identification and Prioritization System, IPS, Tool for the determination of a non-wadeable total phosphorus, TP, target
- Development and calibration of a continuous QUAL2Kw receiving water quality model for the non-wadeable Lower Des Plaines River
- Develop and run various management application scenarios for future conditions to understand the potential impacts of changes to regional and local WWTP discharge limits of total phosphorus concentrations with the IPS target for non-wadeable streams as the goal.
The NARP Implementation for the non-wadeable section of the Lower Des Plaines River is scheduled to be completed by December 2028.
Additionally, in December 2024, the LDWG submitted their NARP for all WWTPs discharging to tributaries of the Des Plaines River. A crucial step in developing this NARP was establishing a watershed threshold concentration for total phosphorus that is protective of aquatic life for the NARP area. For wadeable streams, a relationship between total phosphorus concentrations and fish species, macroinvertebrate taxa and their indices of biotic integrity was established by a multivariate analysis published in 2023 by the DuPage River Salt Creek Workgroup, DRSCW, and Lower DuPage River Watershed Coalition, LDRWC. The analysis, which drew on paired biological, chemical, and physical data from 640 sites in northeast Illinois found fish species and Fish Index of Biotic Integrity, fIBI, were more sensitive to total phosphorus concentration variation than macroinvertebrate taxa and Macroinvertebrate Index of Biotic Integrity, mIBI. The 75th percentile of sites in the fIBI range of 41 and 49 (meeting or exceeding the General Use Standard for aquatic life) was found to correspond to an upper total phosphorus concentration of 0.28 milligrams per liter (mg/l).
The 0.28 mg/L TP instream threshold was utilized to develop appropriate effluent targets for the ten (10) major and three (3) minor WWTPs that discharge to tributaries. Preliminary effluent limits of 1 mg/l (minors), 0.5 mg/l and 0.35 mg/l are recommended based on the observed ambient concentrations downstream of the plant and the facilities current level of TP removal. Limits are preliminary as current ambient data is limited to one year and the NARP recommends future monitoring be implemented ahead of the limit adoption schedule to refine the recommended limits.
Additional details on both NARPs can be found at https://ldpwatersheds.org/about-us/lower-des-plaines-watershed-group/our-work/narp/.
Other Activities
- Working with the LDRWC, the LDWG continues to expand and develop new materials to help members meet MS4 outreach requirements. Campaigns focus on ways residents can reduce their negative impacts on water quality. Topics include using native plants, rain gardens, and rain barrels, detention basin maintenance, pet waste, proper leaf disposal, and reducing chlorides. Outreach materials include social media posts, articles for newsletters and websites, printable handouts, and posters. All materials are available on the website ldpwatersheds.org/outreach with additional winter-related materials at www.SaltSmart.org.
- To further facilitate the coordination of outreach and education activities, a joint website between LDWG and the Lower DuPage River Watershed Coalition was maintained through 2023 and 2024. The website can be found at www.LDPWatersheds.org and includes information about each group and joint information about water quality related topics, stream ecology, involvement opportunities for residents.
- The LDWG, LDWRC, DRSCW, and Chicago Area Waterways Chloride Workgroup, CAWCW, collaborated with staff from Lake County Department of Transportation and Health Department to host technical deicing workshops in 2023 and 2024. In 2023, three virtual Public Roads Deicing Workshops were held and survey results indicate that a minimum of 690 persons from Cook, DuPage, Kane, Lake, McHenry and Will counties attended the workshops. Also, in 2023, two virtual Parking Lots and Sidewalk Deicing Workshops were held and attended by 330 individuals. In 2024, a new Salt Smart Roads Workshop was presented at three in-person and three virtual workshops and survey results indicate that a minimum of 870 persons from Champaign, Cook, DuPage, Fulton, Kane, Kendall, Lake, McHenry and Will counties attended. Additionally in 2024, one in-person and two virtual Parking Lots and Sidewalk Deicing workshops were held with a minimum of 425 persons in attendance.
On Sept. 12, 2023, the LDWG, LDWRC, DRSCW, and CAWCW, the Conservation Foundation, and the SaltSmart Collaborative hosted an in-person Northeast Illinois Salt Conference at Medinah Shriners. Presentations covered Weather and Pavement Temperature, Route Management, and Liquids, Plow Driver training, and the Salt Smart Certified program for parking lots and sidewalks. The workshop was attended by 101 public works directors and supervisors.
