When we talk about water quality, we are looking at the chemical, physical and biological attributes of a stream. The Bioassessment program pairs traditional chemical data with a Qualitative Habitat Evaluation Index (QHEI) score and fish and macroinvertebrate community data. This approach allows us to assess the health of the stream system and to identify stressors to aquatic life.
The Bioassessment Program for the LDWG watershed area is completed over a 5-year cycle, with sampling occurring the first four years and one year off to catch up on report writing. The mainstem Des Plaines River is broken up across the first and second year of sampling. The first year going from the confluence with the Kankakee River up to the I-355 bridge and the second year continuing upstream to just past the confluence with Willow Creek in the Rosemont area. A couple of small tributaries around O’Hare Airport are also picked up in year two. The third year of the cycle focuses on the Hickory Creek Watershed and the fourth year finishes the remaining tributaries, mostly in Will and southeast DuPage Counties.
The first of the Bioassessment Reports will be available by the end of 2021, with a single report for the mainstem Des Plaines River and a separate report for the Hickory Creek Watershed.
In addition to the Bioassessment monitoring, an Expanded Dissolved Oxygen Program was started in 2020 in the Hickory Creek Watershed to further support the development of the Nutrient Assessment and Reduction Plan. This program incorporates week long deployments of multi-parameter probes that collect dissolved oxygen, temperature, pH and specific conductivity data every 15 minutes. During the deployment an expanded suite of water chemistry parameters are collected including sestonic (in the water column) chlorophyll-a. A benthic chlorophyll-a sample is also collected by scraping algae off of rocks for other substate in the stream. The stream cross section and flow are also measured. This information will help us to better understand how nutrients are functioning in the stream. Sites for this analysis are located downstream of wastewater treatment plants and in a few headwater areas. This program will continue for all future sampling seasons.