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Twin Cities Metropolitan Area Chloride Management Plan
What is the TCMA Chloride Management Plan?
The Minnesota Pollution Control Agency (MPCA) has worked with stakeholders in the Seven County Twin Cities Metropolitan Area (TCMA) to assess the level of chloride in water resources, including lakes, streams, wetlands and groundwater. There are two primary sources of chloride to the TCMA water resources: 1) salt applied to roads, parking lots and sidewalks for deicing; and 2) water softener brine discharges to municipal wastewater treatment plants (WWTPs). The MPCA and stakeholders also worked together to develop a plan to restore and protect waters impacted by chloride. This Chloride Management Plan (CMP) incorporates water quality assessment, source identification, implementation strategies, monitoring recommendations, and measurement and tracking of results into a performance-based adaptive approach for the TCMA. The goal of this plan is to develop the framework to assist local partners in minimizing salt (chloride) use and provide safe and desirable conditions for the public.
The CMP is intended to characterize water resources across the TCMA and the overall impacts of chloride. As part of the CMP, waters not meeting state standards have been listed as impaired and Total Maximum Daily Loads (TMDLs) developed. However, water quality is not the only factor driving the need to reduce chloride entering TCMA waters. Improved practices for anti-icing and deicing roads, parking lots and sidewalks not only reduce chloride impacts on water quality, but they can also lead to long-term cost-savings as a result of purchasing less salt for winter maintenance and reduced impacts on vegetation and corrosion of infrastructure and vehicles. A key challenge in reducing salt usage is balancing the need for public safety with the growing expectation for clear, dry roads, parking lots, and sidewalks throughout the mix, severity, and duration of winter conditions in the TCMA. Notable efforts have already been made by the Minnesota Department of Transportation (MnDOT) and some TCMA cities, counties, and others to improve winter maintenance while reducing salt usage. This CMP is intended to learn from and build on these efforts. The CMP will guide and assist agencies, local governments, and other TCMA stakeholders in determining how best to restore and protect water resources impacted by elevated chloride levels while balancing the need for public safety, level of service considerations, as well as water softening needs. This CMP is not intended to resolve all issues. Rather, it provides understanding and guidance for management activities over the next 10 years. While this plan was developed to address chloride impacts specifically to waters in the TCMA, the restoration and protection goals, implementation strategies, and monitoring and tracking recommendations can be applied statewide. The purpose, scope and audience for the CMP are presented on the next page.
Purpose - Scope - Audience
Purpose
- Highlight the impacts of chloride on TCMA water quality
- Develop an appreciation of the competing demands of level of service and reduced salt usage
- Set performance-based goals for restoration and protection
- Inform and guide implementation of improved winter maintenance practices and policy needs
- Demonstrate the success and economic benefits of improved practices
Scope
- Status and trends of chloride levels in lakes, wetlands, streams and groundwater
- Sources of chloride
- Restoration and protection goals
- Implementation strategies to reduce chloride impacts
- Educational and training resources
- Continued monitoring , tracking and adaptive management
Audience
- Local working groups (local governments, watershed management groups, etc.)
- Winter maintenance groups (MnDOT, local governments, private applicators, commercial property owners, residents, etc.)
- Elected officials and policy-makers
- State agencies (MPCA, MnDOT, DNR, BWSR, etc.)