The DuPage River Salt Creek Workgroup, DRSCW, formed in 2005 in response to concerns about Total Maximum Daily Loads, TMDLs, developed for the east and west branches of the DuPage River and Salt Creek located in portions of Cook, DuPage, and Will counties in northeastern Illinois. The DRSCW seeks to implement targeted watershed activities that resolve priority waterway problems cost- effectively.
In 2015 and 2020, a Special Condition to DRSCW National Pollutant Discharge Elimination
System permits was added that substantially increased financial commitments to restoration efforts focused on improving aquatic life. The Special Condition includes 10 stream restoration projects, two studies, and the development of a Nutrient Implementation Plan.
For more information, see drscw.org.
Physical Projects
Spring Brook Phase 2
In 2023 and 2024, Year 3 and 4 of a planned five-year post-project monitoring was conducted at the Phase 2, Stream Restoration Project at the Blackwell Forest Preserve in Wheaton, DuPage County. This stream restoration project included the removal of the Arrow Road dam. The channel was realigned into the adjacent floodplain in order to increase sinuosity, mimic natural geomorphology, and create 22.8 acres of wetlands. After four years of post-project monitoring, Spring Brook Phase 2 met its post-project targets for Qualitative Habitat Evaluation Index and Fish Index of Biotic Integrity both within the project footprint and at sites monitored as part of the post-project impact evaluation. Post-project Macroinvertebrate Index of Biotic Integrity, mIBI, targets were not met but are expected to continue to increase at the site as the restoration project matures.
Klein Creek Streambank Stabilization Project
The DRSCW entered a Memorandum of Understanding with the Village of Carol Stream to fund the river resource improvement elements of the Klein Creek Section Stream Bank Stabilization Project which was completed in 2022. This project re-meandered a section of the channel and increased its length approximately 200 feet. As the longitudinal slope was too flat for riffle structures, two rock substrate areas were added to provide riffle-type benefits. Stream banks were stabilized with vegetated rock toes or rootwads embedded at outside bends, as well as rock vanes (stream barbs) at strategic locations. The top of bank was lowered adjacent to approximately 1.4 acres of newly created wetlands.
Activities in 2023 and 2024 at the project focused on plantings and maintenance and monitoring activities. Trees and shrubs were planted in late spring 2023 and plugs were planted in early fall 2023.
Maintenance and monitoring continued in 2024 and included several naturalized areas: 16.76 acres of upland prairie/economy prairie, 3.74 acres of open riparian area, 1.44 acres of sedge meadow, and 0.93 acres of shallow emergent area. Based on the results of the 2024 monitoring, the project exceeded expectations for its second year. Planted species, as well as native species from the seed soil bank, are abundant and will continue to increase in coverage in 2025. The in-stream structures, upland restoration zones, and wetland restoration zones have all met the designated second-year performance standards and are expected to exhibit continued progression in subsequent growing seasons.
2024 was also the first year for biological monitoring and for habitat five-year post-project monitoring at the site. Post-project Macroinvertebrate Index of Biotic Integrity, Fish Index of Biotic Integrity, and Qualitative Habitat Evaluation Index have all improved since the pre-project monitoring and are expected to continue to increase as the restoration matures.
Fullersburg Woods Dam Removal and Stream Restoration
In November 2023, the DRSCW, in cooperation with the Forest Preserve District of DuPage County, began construction on the Fullersburg Woods Dam Removal and Stream Restoration Project in the Fullersburg Woods Forest Preserve in the Village of Oak Brook and DuPage County. The project was designed and permitted with assistance from Hey and Associates. It was constructed by V3 Companies with construction management services provided by the Metropolitan Water Reclamation District of Greater Chicago. The project objectives were to establish fish passage on Salt Creek by removing the Graue Mill Dam, to improve dissolved oxygen, and to raise Macroinvertebrate Index of Biotic Integrity, Fish Index of Biotic Integrity, and Qualitative Habitat Evaluation Index scores in Salt Creek.
On November 27, 2023, instream work for the removal of the Graue Mill Dam, also known as the Fullersburg Woods, began with the installation of a causeway upstream of the dam. Dam demolition began on Nov. 30, 2023. By the end of that day the majority of the dam above the water line had been removed. December 2023 work focused on the removal of the dam to its spread footing and the removal of the dewatering structure located on the north bank. Construction of Riffle #1 at the former location of the dam began Dec. 15, 2023, and was completed by Dec. 19.
Summer 2024 activities focused on the installation of stream restoration practices along 1.25 miles of Salt Creek upstream of the former dam. Eight additional riffles were installed upstream of Riffle #1. The original project design also included pool excavation upstream of each constructed riffle. However, a site survey conducted after the dam removal found the presence of existing, natural pools upstream of riffles 3, 4, and 8. Additionally, pools 2, 5, and 6 were eliminated from the design due to the channel configuration of Salt Creek post dam removal. Approximately 1,000 linear feet of bank stabilization was installed in summer 2024.
In addition to the stream restoration practices, all of the amenities included in the Master Plan for Salt Creek at Fullersburg Woods were installed in the summer and fall of 2024. Amenities near Graue Mill included an ADA-accessible trail, a river overlook, a landscape feature smaller overlook on the opposing bank, a re-designed mill raceway with water source, cascade, and motor to turn the waterwheel. Work conducted by the Fullersburg Woods Nature Center included rehabilitation and waterproofing the existing, failing, floodwall.
Seeding of all disturbed areas associated with the project was completed in November and December 2024. In total, 11.25 acres of wetland conversion, 23.6 acres of wetland enhancement, and 14.5 acres of upland buffer were seeded. Impact assessment of biological metrics and water chemistry will commence in 2025.
Nutrient Implementation Plan
In December 2023 the DRSCW, in cooperation with the Lower DuPage River Watershed Coalition submitted the Nutrient Implementation Plan, NIP, for the East Branch DuPage River, West Branch DuPage River, Lower DuPage River, and Salt Creek to the Illinois Environmental Protection Agency. A crucial step in developing this NIP was establishing a watershed threshold concentration for total phosphorus that is protective of aquatic life in the NIP area. A relationship between total phosphorus concentrations, fish species and macroinvertebrate taxa and their indices of biotic integrity was established using a multivariate analysis published in 2023 by the watershed groups. The analysis, which drew on paired biological, chemical, and physical data from 640 sites in northeast Illinois, found fish species and the Fish Index of Biotic Integrity, fIBI, were more sensitive to total phosphorus concentration variation than the macroinvertebrate taxa and the Macroinvertebrate Index of Biotic Integrity. The 75th percentile of sites in the fIBI range of 41 and 49 (meeting and exceeding the General Use standard for aquatic life) was found to correspond to an upper total phosphorus threshold concentration of 0.277 milligrams per liter. The NIP adopted this as the upper threshold of the watershed total phosphorus target.
Analysis of the mean total phosphorus concentrations at sites monitored by the watershed groups’ rolling bioassessments under various flow regimes show a clear differentiation between sites. Water downstream of Waste Water Treatment Plants, WWTPs, is a product of both wastewater and non-wastewater. Non-wastewater is comprised of stormwater and background sources, summarized as urban. Annual mean concentrations at these sites ranged from 0.70 mg/L to 2.12 mg/L. Concentrations at urban-only sites, or upstream of any WWTP influence, had total phosphorus concentrations ranging nearly an order of magnitude lower, 0.03–0.53 mg/L. Instream flow was an important factor, with total phosphorus concentrations falling both at wastewater-influenced and at urban sites as flow increased. Mean annual concentrations at all urban sites were beneath the watershed threshold of 0.277 mg/L in all years sampled when flows were above the 25th percentile. Sites downstream of WWTPs outfalls had a total phosphorus concentration significantly higher than the watershed threshold in all years. Aggregation of the flows and water quality data to allow for reduction scenarios modeling showed that while WWTPs contributed 13% to 28% of annual flow, they contributed more than 80% of annual ambient instream total phosphorus.
Modeling was conducted using the QUAL2Kw platform to identify potential management scenarios that would decrease ambient instream total phosphorus concentrations below the identified total phosphorus watershed threshold. Receiving water models were developed for each basin and included the connectivity of the East and West Branches of the DuPage River model outputs to inform the headwater conditions of the Lower DuPage River. Notably the headwater condition includes the assumption, as recommended by the NIP, that all upstream WWTPs will be operating with a 0.35 mg/L total phosphorus limit. Following model calibration, channel geometry and hydraulics were modified for the Lower DuPage River and Salt Creek to reflect the imminent removals of dams on these waterways; both dams have since been removed. Ultimately, the suite of scenarios modeled demonstrated that an effluent total phosphorus permit limit of 0.35 mg/L (for an effective effluent concentration of 0.28 mg/L) for WWTPs along Salt Creek and the West and East Branches of the DuPage River would be sufficient to achieve the watershed threshold value satisfactorily.
The modeled reductions of effluent total phosphorus concentrations did not show meaningful improvements in predicted minimum and mean dissolved oxygen, DO, concentrations due in part to localized persistence of low gradients or flow restrictions which also factor into existing DO impairments.
The NIP recommended implementation of targeted physical projects focused on eliminating DO sags and improving instream habitat. Recommendations include that WWTPs discharging to Salt Creek and the East and West Branches of the DuPage River adopt an effluent limit of 0.35 mg/L total phosphorus. This limit would lead to an effective mean effluent concentration of 0.28 mg/L, assuming a 20% margin of safety. The limit would be a seasonal geometric mean for warm weather months of May through October as part of an annual 0.50 mg/L total phosphorus geometric mean.
