TCMA Chloride TMDL - Monitoring Recommendations
Monitoring Recommendations
Addressing the issue of chloride impacts on the environment in the TCMA is a long-term endeavor and it may take some time before water quality improvements are seen due to historical loadings, groundwater inputs, variable residence times, and other complicating factors. Therefore, continued monitoring of the TCMA lakes, wetlands, and streams for chloride is critical as well as the need to document changes in winter maintenance activities, wastewater source discharges, and water softener usage. Continued water quality monitoring, along with improved understanding of the sources of chloride, will allow adaptive management to take place and inform future steps needed to restore and protect the TCMA waters. The CMP is intended to be revisited within five years and revised based on improved understanding.
The MPCA has worked with the Monitoring Sub-Group to develop monitoring guidelines for lakes, streams, wetlands and storm sewers. Monitoring guidance documents are available on the MPCA Chloride Project website at: Metropolitan Area Chloride Project. The key components of continued monitoring to support the implementation of the CMP include:
- Collect samples during the critical periods for elevated chloride concentrations: January through May for lakes; and December through April for streams. However, always put safety first when assessing conditions for collection of samples through the ice.
- Analysis of chloride should also be included in typical summer season sampling. Analysis for chloride is relatively inexpensive and should be included if the effort is being made to collect samples for analysis of other parameters, such as phosphorus.
- In lakes with potential for stratification, collect a bottom sample and surface sample.
- Maintain consistency in sampling. Chloride concentrations may vary from year-to-year depending on the winter conditions. Assessment of long-term trends to determine if lakes and streams are improving or degrading will have greater confidence with consistent yearly datasets.
- Collect a "matching" conductivity reading with each sample taken for chloride analysis.
- Expand the sampling program to additional lakes, streams and wetlands as resources allow. Many waterbodies in the TCMA have not been sampled sufficiently to make a reliable assessment of potential impairment by chloride.
There are a number of organizations across the TCMA that monitor water quality or partner with others to conduct monitoring. In addition the MPCA, Metropolitan Council and the United States Geological Survey (USGS) also collect data throughout the TCMA. Incorporating the recommendations below into existing local water monitoring programs will provide valuable data to assist with tracking progress and meeting water quality goals. Monitoring should take place at the existing sites for consistency and comparison purposes. However, since monitoring activities are lead at the local level it will be dependent on available resources and local priorities. We encourage local monitoring data be shared with MPCA by routinely submitting data to the MPCA’s water quality database, EQuIS. The monitoring that MPCA conducts across the state follows the 10-year monitoring strategy as described in Minnesota’s Water Quality Monitoring Strategy report.