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Time Limited Water Quality Standard for Chloride

The Chicago Area Waterways Chloride Workgroup (CAWCW) will be coordinating the implementation of the Time Limited Water Quality Standard for Chloride (aka the Chloride Variance or Chloride TLWQS) for the portion of the Chicago Area Waterways System (CAWS) that is included in the variance. 

In the early 2010s discussion began about changing the designated use for the Chicago Area Waterways System. As part of the rulemaking process, the Illinois Pollution Control Board adopted aquatic life water quality standards. This included an update to the water quality standard for chloride from 1,500 mg/L during the winter and 500 mg/L during the summer to 500 mg/L all year round. This change in the chloride water quality standard took effect in 2018.  

Portions of the CAWS were not going to meet this new standard, especially during the winter. Individual petitioners submitted petitions for a variance to the new standard in 2015 and a joint submittal for a watershed-based variance was submitted in 2018 with additional petitioners signing on to the joint petition. Between 2015 and 2018, a lot of work was done by a variety of organizations working together to set the groundwork for the Chloride variance and justify the need for the variance. In addition, milestones and best management practices were included in return for allowing the variance so that progress can be made towards ultimately reaching general use water quality standard for the watersheds.  

Between 2018 and 2020 public comments were collected incorporated into the variance and a public hearing was held by the Illinois Pollution Control Board in February 2020. Additional post-hearing public comments were received to provide additional input to the variance.  

On November 4, 2021, the Illinois Pollution Control Board issued an Opinion and Order for the Time Limited Water Quality Standard for Chloride for portions of the CAWS and Lower Des Plaines Watersheds. The Lower Des Plaines Watershed was included as it is receives water from the CAWS. Requirements of the Chloride TLWQS begin on Page 65 of the Illinois Pollution Control Board’s Opinion and Order Document from November 4, 2021. On January 6, 2022, the Illinois Pollution Control Board issued an order clarifying the November 4, 2021 opinion and order for the Chloride TLWQS. The CAWCW strongly encourages petitioners to read the November 4, 2021 order and the January 6, 2022 clarifying order for the exact language and requirements related to the Chloride TLWQS. The CAWCW prepared a summary handout for members about the Chloride TLWQS and the requirements for petitioners. Once the USEPA grants approval, the Illinois EPA will write permits to include the Chloride TLWQS requirements for all of the petitioners involved. 

The Chloride TLWQS is a watershed-based approach to reducing the amount of chloride in the CAWS and Lower Des Plaines River. This will be one of the first watershed-based variances adopted by the Illinois Pollution Control Board. Typically, variances to water quality standards are requested on an individual petitioner basis. The Chloride Variance Petition has over 40 agencies and organizations from across the CAWS and Lower Des Plaines watersheds participating as joint petitioners. Implementing various requirements of the Chloride TLWQS are done at a watershed wide scale rather than individually, including reporting, training, and outreach. All petitioners are required to join one of the two watershed workgroups providing this coordination, the CAWCW or the Lower Des Plaines Watershed Group. 

The Chloride TLWQS requires all petitioners to create Pollutant Minimization Plans and implement specific best management practices based on their operations to reduce their chloride use. Some of these best management practices include annual training, outreach on chlorides, ensuring good housekeeping practices, and reporting of annually on their progress. The reduction efforts made by the petitioners is a big step towards reducing chlorides getting into our waterways, all while ensuring public safety during winter weather. By following industry recognized best management practices will allow the petitioners to maintain their expected level of service to their communities, while using less salt.