Appendix A – TCMA Chloride Total Maximum Daily Loads (TMDLs)

Twin Cities Metropolitan Area Chloride Total Maximum Daily Load Study

Project Overview


The TCMA includes Anoka, Hennepin, Ramsey, Washington, Carver, Scott, and Dakota counties, 186 cities and townships and a population of approximately 3,000,000 people. It covers approximately 3,000 square miles with about one-third in urbanized areas. The area is fortunate to be home to nearly 1,000 lakes, creeks, and rivers. These water resources hold high value to the community and visitors to the area.

The TCMA receives approximately 54 inches of snow each year on average. The thousands of miles of streets and highways in the TCMA, along with parking lots and sidewalks, must be maintained to provide safe conditions throughout the winter. Winter maintenance of these surfaces currently relies heavily on the use of salt, primarily sodium chloride (NaCl), to prevent ice build-up and remove ice where it has formed. The chemical properties of sodium chloride make it effective at melting ice, but these properties also result in the chloride dissolving in water and persisting in the environment. The dissolved chloride moves with the melted snow and ice, largely during spring warm-ups, and ends up in the nearby lakes, streams, wetlands and groundwater. Residential water softener use is also a significant source of chloride. In areas with high hardness in their water supply, residential water softeners which use salt are common. The chloride from water softeners makes its way to the environment either through discharge to a septic system or by delivery to a municipal WWTP. Chloride is not removed from wastewater using conventional treatment methods.

At levels exceeding the WQS, chloride is toxic to aquatic life. Water samples from lakes, streams, wetlands, and groundwater show an increasing trend in chloride levels in urban areas across the state. Available monitoring data indicates 39 waterbodies in the TCMA currently exceed chloride levels protective of the aquatic community. This trend calls for immediate attention to the issue, the development of a plan to restore waters already impaired, and protection of waters at risk of further degradation.

The goal of this TMDL study is to:

  1. Determine the allowable chloride loading to impaired lakes, wetlands and streams in the TCMA;
  2. Allocate the allowable loading to the various sources of chloride and establish reasonable and practical expectations for meeting reduction goals; and
  3. Provide stakeholders and chloride users with guidance and tools to improve

Identification of Waterbodies

This TCMA Chloride Special Assessment conducted by the MPCA from 2013-2014 includes 39 waterbodies listed as impaired for chloride in the TCMA. Previously, two streams that had been listed as impaired by chloride had TMDLs developed and approved by the United States Environmental Protection Agency (EPA) (Nine Mile Creek and Shingle Creek). The lakes, streams, and wetlands included on the MPCA’s 303(d) list of impaired waters for chloride are shown in the 2014 Twin Cities Metro Chloride Assessment image and listed in the Lakes and wetlands impaired by chloride in the TCMA and Streams impaired by chloride in the TCMA table. High Risk waters are also shown in the 2014 Twin Cities Metro Chloride Assessment image; however, this TMDL has been developed to address only the impaired waters. See the TCMA Chloride Management Plan for protection strategies.

Lakes and wetlands impaired by chloride in the TCMA
Link to this table

Waterbody Name Waterbody Description Year Added to List Basin Lake or Wetland AUID (County + Lake) TMDL Target Start TMDL Target Completion
Battle Creek Lake 2014 UMiss 82-0091-00 2009 2015
Brownie Lake 2014 UMiss 27-0038-00 2009 2015
Carver Lake 2014 UMiss 82-0166-00 2009 2015
Como Lake 2014 UMiss 62-0055-00 2009 2015
Diamond Wetland 2014 UMiss 27-0022-00 2009 2015
Kasota Pond North Wetland 2014 UMiss 62-0280-00 2009 2015
Kasota Pond West Wetland 2014 UMiss 62-0281-00 2009 2015
Kohlman Lake 2014 UMiss 62-0006-00 2009 2015
Little Johanna Lake 2014 UMiss 62-0058-00 2009 2015
Loring (South Bay) Lake 2014 UMiss 27-0655-02 2009 2015
Mallard Marsh Wetland 2014 UMiss 62-0259-00 2009 2015
Parkers Lake 2014 UMiss 27-0107-00 2009 2015
Peavey Lake 2014 UMiss 27-0138-00 2009 2015
Pike Lake 2014 UMiss 62-0069-00 2009 2015
Powderhorn Lake 2014 UMiss 27-0014-00 2009 2015
Silver Lake 2014 UMiss 62-0083-00 2009 2015
South Long Lake 2014 UMiss 62-0067-02 2009 2015
Spring Lake 2014 UMiss 27-0654-00 2009 2015
Sweeney Lake 2014 UMiss 27-0035-01 2009 2015
Tanners Lake 2014 UMiss 82-0115-00 2009 2015
Thompson Lake 2014 UMiss 19-0048-00 2009 2015
Valentine Lake 2014 UMiss 62-0071-00 2009 2015
Wirth Lake Proposed 2016 - UMiss 27-0037-00 2009 2015

- Recent local water quality data indicates multiple exceedances of the standard. A formal assessment and listing process will be conducted when the data are received. The 2014 list is currently draft and has not yet been approved by EPA.

Streams impaired by chloride in the TCMA
Link to this table

Waterbody Name Waterbody Description Year Added to List Basin River AUID TMDL Target Start TMDL Target Completion
Bass Creek Unnamed wetland (27-0096-00) to Eagle Cr 2002 UMiss 07010206-784 2009 2015
Bassett Creek Medicine Lk to Mississippi R 2010 UMiss 07010206-538 2009 2015
Battle Creek Battle Creek Lk to Pigs Eye Lk 2008 UMiss 07010206-592 2009 2015
Elm Creek Headwaters (Lk Medina 27-0146-00) to Mississippi R 2014 UMiss 07010206-508 2009 2015
Judicial Ditch 2 Headwaters to Sunrise R 2012 StC 07030005-525 2009 2015
Minnehaha Creek Lk Minnetonka to Mississippi R 2008 UMiss 07010206-539 2009 2015
Ninemile Creek Headwaters to Minnesota R 2004 MnR 07020012-518 - -
Raven Stream E Br Raven Str to Sand Cr 2010 MnR 07020012-716 2009 2015
Raven Stream, East Branch Headwaters (Lk Pepin 40-0028-00) to Raven Str 2010 MnR 07020012-543 2009 2015
Rush Creek, South Fork Unnamed lk (27-0439-00) to Rush Cr 2014 UMiss 07010206-732 2009 2015
Sand Creek Porter Cr to Minnesota R 2014 MnR 07020012-513 2009 2015
Sand Creek T112 R23W S23, south line to Raven Str 2010 MnR 07020012-662 2009 2015
Shingle Creek Headwaters (Eagle Cr /Bass Cr) to Mississippi R 1998 UMiss 07010206-506 - - - -
Unnamed creek Headwaters to Medicine Lk 2014 UMiss 07010206-526 2009 2015
Unnamed creek Unnamed ditch to wetland 2014 UMiss 07010206-718 2009 015
Unnamed creek Unnamed lk (62-0205-00) to Little Lk Johanna 2014 UMiss 07010206-909 2009 2015

- TMDL plan approved 2010 – EPA TMDL ID #40253 - - TMDL plan approved 2007 – EPA TMDL ID #32032

This map shows the2014 Twin Cities Metro Chloride Assessment
2014 Twin Cities Metro Chloride Assessment

Priority Ranking

The MPCA’s projected schedule for the TMDL completions, as indicated on the 303(d) impaired waters list and the 2014 Twin Cities Metro Chloride Assessment image and listed in the Lakes and wetlands impaired by chloride in the TCMA and Streams impaired by chloride in the TCMA table above, implicitly reflects Minnesota’s priority ranking of this TMDL. Ranking criteria for scheduling TMDL projects include, but are not limited to: impairment impacts on public health and aquatic life; public value of the impaired water resource; likelihood of completing the TMDL in an expedient manner, including a strong base of existing data and restorability of the waterbody; technical capability and willingness locally to assist with the TMDL; and appropriate sequencing of TMDLs within a watershed or basin.

TCMA Chloride TMDL - Executive Summary

TCMA Chloride TMDL - Applicable Water Quality Standards and Numeric Water Quality Targets

TCMA Chloride TMDL - Watershed and Waterbody Characterization

TCMA Chloride TMDL - TMDL Development

TCMA Chloride TMDL - Future Growth Consideration/Reserve Capacity

TCMA Chloride TMDL - Monitoring Recommendations

TCMA Chloride TMDL - Implementation Strategy Summary

TCMA Chloride TMDL - Public Participation

TCMA Chloride TMDL - Literature Cited

TCMA Chloride TMDL - Water Quality Dashboards and Watershed Areas

TCMA Chloride TMDL - Impaired and High Risk Waterbodies by Location

TCMA Chloride TMDL - NPDES Point Source Permits by Waterbody

TCMA Chloride TMDL - TMDL Tables

Related pages

This page was last edited on 23 November 2022, at 16:37.