TCMA Chloride Management Plan - TCMA Chloride Conditions

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This section of the manual is under construction and will be populated over the next few months. Changes and updates will be posted in the What's new page in the manual. Information on road salt and water quality can be found on MPCA's website

Chloride data across the TCMA was compiled and assessed to support the development of the CMP. As part of the TCMA Chloride Project, the MPCA worked with local partners to develop and implement a chloride monitoring program. The objective of the monitoring program was to better inform an understanding of chloride conditions across the TCMA, including seasonality, trends over time, and the potential for high chloride concentrations in the deepest part of lakes. Seventy-four lakes, 27 streams, and eight storm sewers were monitored as part of this effort from 2010-2013. The Chloride Monitoring Guidance for Lakes and Chloride Monitoring Guidance for Streams and Stormsewers were developed by the MPCA and local experts from the TCMA Chloride MSG and can be found on the MPCA’s TCMA Chloride Project website. The monitoring guidance provides recommendations on sample collection, times of the year to sample, as well as guidance for monitoring high risk waters. In addition to data collected in 2010-2013 following the TCMA Chloride Project monitoring program, chloride data from a host of other sources and timeframes were compiled. The data were collected by several local organizations including the MPCA, the United States Geological Survey (USGS), Capitol Region Watershed District (CRWD), Metropolitan Council Environmental Services (MCES), Minneapolis Park & Recreation Board (MPRB), Minnehaha Creek Watershed District (MCWD), Mississippi Watershed Management Organization (MWMO), Ramsey County Environmental Services, Ramsey-Washington Metro Watershed District (RWMWD), Rice Creek Watershed District, Scott County Watershed Management Organization, and Three Rivers Park District. A large portion of the data were compiled and submitted to the State of Minnesota’s Environmental Quality Information System database (EQuIS). All data collected by Metropolitan Council are available on their Environmental Information Management System (EIMS) database, and data collected by USGS are available on their water-quality data for the Nation database: waterdata.usgs.gov/nwis/qw.

Information: A STREAM, LAKE OR WETLAND IS IMPAIRED BY CHLORIDE IF Two or more samples exceed 230 mg/L within a three-year period; Or, One sample exceeds 860 mg/L.

The impacts of climate change create uncertainty related to winter salt application and chloride levels in TCMA waters in the future. Predictions provided by the United States Global Change Research Program for the TCMA area include warmer winter temperatures by 5 - 6 degrees Fahrenheit, longer freeze-free seasons increasing by 20-30 days, greater winter precipitation, and the likelihood of more frequent extreme events (Kunkel et al. 2013). On the one hand, these predictions of climate change may result in reduced salt use. On the other hand, more frequent snow events, more extreme events, and potentially more frequent ice storms may result in greater needs for deicing roads. Continued monitoring of climate change and chloride concentrations in the TCMA waters, tracking of salt use on all paved surfaces, and an adaptive process will be needed to restore and protect the TCMA waters from chloride impairments with the prospects of a changing climate.

The remainder of this section will present an overview of the assessments conducted based on the available data, including determinations of impairment, time and spatial trends in chloride concentrations, the TMDLs developed for impaired waters, and waters showing a high-risk for future impairment.

TCMA Chloride Management Plan - TCMA Chloride Conditions - Condition status

TCMA Chloride Management Plan - TCMA Chloride Conditions - Chloride sources

TCMA Chloride Management Plan - TCMA Chloride Conditions - Chloride trends

TMDL summary

The Total Maximum Daily Loads (TMDLs) were developed for each of the lakes, wetlands and streams in the TCMA impaired for chloride, with the exception of Shingle Creek and Nine Mile Creek which already have existing TMDLs. A TMDL quantifies the allowable pollutant loading to a lake, wetland, or stream that will result in water quality standards being attained. The water quality target for the TMDLs was set to the chronic water quality criterion for chloride of 230 mg/L. The total allowable load, or TMDL, is allocated to the various sources contributing chloride as well as consideration of a margin of safety and reserve capacity. Margin of safety is intended to account for uncertainty in the development of the TMDL. Reserve capacity is intended to set-aside a portion of the TMDL for future growth. For the TCMA chloride TMDLs, reserve capacity was set to zero assuming that any further development and additional impervious surfaces would be expected to have the same level of best management practices (BMPs) implemented for winter maintenance activities as for the remainder of the watershed. The complete details of the TMDL development are presented in the TCMA Chloride TMDL report (see Appendix A).

A total of 39 waterbodies are listed as impaired by chloride, and TMDLs for Shingle Creek and Nine Mile Creek have already been prepared under separate projects. A total of 37 TMDLs were completed as part of this project. Summaries of the TMDLs are presented in the Summary of TMDL and Components for Impaired Lakes and Wetlands in the TCMA table for lakes and the wetlands and the Summary of TMDL and Components for Impaired Streams in the TCMA table.

Summary of TMDL and Components for Impaired Lakes and Wetlands in the TCMA
Link to this table

Lake/Wetland	AUID	Watershed Area (ac)	TMDL and Components (all values in lbs/yr of chloride)
			Loading Capacity (TMDL	WLA		LA		Margin of Safety
				MS4 Categorical	Wastewater Sources1	Non-Permitted Aggregate	Natural Background
Battle Creek Lake	82-0091-00	4,326	2,153,699	1,766,033	0	0	172,296	215,370
Brownie Lake	27-0038-00	452	341,418	279,963	0	0	27,313	34,142
Carver Lake	82-0166-00	2,242	1,071,123	878,321	0	0	85,690	107,112
Como Lake	62-0055-00	1,850	994,078	815,144	0	0	79,526	99,408
Diamond Lake	27-0022-00	744	486,017	398,534	0	0	38,881	48,602
Kasota Ponds North	62-0280-00	10	6,234	5,112	0	0	499	623
Kasota Ponds West	62-0281-00	6	5,742	4,708	0	0	459	574
Kohlman Lake	62-0006-00	7,533	4,839,183	3,106,733	1,050,484	0	303,096	378,870
Little Johanna Lake	62-0058-00	1,703	1,224,242	1,003,879	0	0	97,939	122,424
Loring Pond (South Bay)	27-0655-02	34	9,764	8,007	0	0	781	976
Mallard Marsh	62-0259-00	16	9,851	8,077	0	0	788	985
Parkers Lake	27-0107-00	1,064	1,431,262	528,161	787,163	0	51,528	64,410
Peavey Lake	27-0138-00	776	205,995	165,889	3,692	0	16,184	20,230
Pike Lake	62-0069-00	5,735	3,591,268	2,943,971	1,059	0	287,217	359,021
Powderhorn Lake	27-0014-00	332	218,588	179,242	0	0	17,487	21,859
Silver Lake	62-0083-00	655	370,011	303,409	0	0	29,601	37,001
South Long Lake	62-0067-02	114,785	26,334,624	21,534,261	4,030	0	2,106,448	2,633,059
Spring Lake	27-0654-00	39	15,600	12,792	0	0	1,248	1,560
Sweeney Lake	27-0035-01	2,439	1,456,271	1,194,142	0	0	116,502	145,627
Tanners Lake	82-0115-00	1,732	826,520	677,746	0	0	66,122	82,652
Thompson Lake	19-0048-00	178	134,340	110,159	0	0	10,747	13,434
Valentine Lake	62-0071-00	2,404	1,165,072	955,359	0	0	93,206	116,507
Wirth Lake	27-0037-00	426	1,095,000	897,900	0	0	87,600	109,500

¹ WLA=0 in the wastewater sources column means that there is no wastewater discharges in that watershed

Summary of TMDL and Components for Impaired Streams in the TCMA
Link to this table

Stream	AUID	Watershed Area (ac)	TMDL and Components (all values in lbs/yr of chloride)
			Loading Capacity (TMDL	WLA		LA		Margin of Safety
				MS4 Categorical	Wastewater Sources1	Non-Permitted Aggregate	Natural Background
Bass Creek	07010206-784	5,434	1,746,399	1,432,047	0	0	139,712	174,640
Bassett Creek	07010206-538	25,209	9,334,219	6,642,961	1,233,048	0	648,094	810,117
Battle Creek	07010206-592	7,246	2,328,721	1,909,551	0	0	186,298	232,872
Elm Creek	07010206-508	66,382	21,332,410	17,386,888	0	105,688	1,706,593	2,133,241
Judicial Ditch 2	07030005-525	1,587	510,115	418,294	0	0	40,809	51,011
Minnehaha Creek	07010206-539	109,151	35,997,083	28,679,140	1,004,128	0	2,806,140	3,507,675
Raven Stream	07020012-716	42,750	15,023,193	442,771	1,284,983	10,822,561	1,099,057	1,373,821
Raven Stream, East Branch	07020012-543	14,751	6,025,349	442,093	1,284,983	3,445,007	379,229	474,037
Rush Creek, South Fork	07010206-732	13,844	4,470,069	3,646,696	21,010	1,532	355,925	444,906
Sand Creek (South) - includes 07020012-662	07020012-513	175,578	59,480,179	4,402,547	3,056,425	41,864,932	4,513,900	5,642,375
Unnamed creek (Headwaters to Medicine Lk)	07010206-526	6,447	2,071,959	1,699,006	0	0	165,757	207,196
Unnamed creek (Unnamed ditch to wetland)	07010206-718	793	254,852	208,979	0	0	20,388	25,485
Unnamed Stream (Unnamed lk 62-0205-00 to Little Lk Johanna)	07010206-909	1,627	522,817	428,710	0	0	41,825	52,282

¹ WLA=0 in the wastewater sources column means that there is no wastewater discharges in that watershed

Protection of surface and groundwater

Protection is an opportunity to prevent waters from continued degradation which may result in impairment. Prevention or protection is often more easily accomplished than the restoration of an impaired waterbody. Protection efforts also may eliminate the need for additional permit and other regulatory requirements to reduce pollution. Successful protection efforts rely on understanding how current practices or conditions may be contributing to water quality conditions.

High risk surface waters

Preventing a waterbody from being contaminated with chloride is easier and more cost effective than restoration. Chloride is a conservative ion and will not break down over time but rather it accumulates in waters. Therefore, efforts should be made to protect waters that show an increasing trend in chloride concentration or have been shown to have chloride concentrations approaching the water quality criteria. Lakes, wetlands, or streams with at least one sample within 10% of the chronic water quality standard within the last 10 years have been identified as a high risk waterbody (one exceedance of 207 mg/L chloride). Proactive actions to reduce chloride loads to these high risk waterbodies should be pursued. Proactive actions similar to actions listed for impaired waters should be explored to protect high risk waters. These waters are considered to be approaching the water quality standard and if no actions are taken, they will likely reach impairment status in the near future. The TCMA lakes and streams identified as being at high risk for potential chloride impairment are shown in the High Risk Lakes in the TCMA table and the High Risk Streams in the TCMA table, respectively.

It should be noted that there are potentially many more high risk waters in the TCMA that have not been identified because there is limited or no monitoring data available for those waters. For this reason, similar proactive approaches to chloride management should be taken to prevent chloride contamination.

All surface waters and groundwater

In addition to the high risk waters listed above, protecting all surface waters and groundwater from further degradation due to chloride is important. By implementing salt reducing practices throughout the TCMA, both the need to restore those waters already impaired and also protect those waters not yet exceeding the standard are addressed. The practices necessary for protection of groundwater are the same as those for restoring and protecting surface waters. Through targeting and prioritization a starting point can be established. Management practices and BMPs used for impaired and high risk waters can be the same for all waterbodies and should provide the same level of protection and chloride reduction.

High risk lakes in the TCMA
Link to this table

Lakes	AUID
Beaver Lake	62-0016-00
Bennett Lake	62-0048-00
Calhoun Lake	27-0031-00
Centerville Lake	02-0006-00
Crosby Lake	62-0047-00
Crystal Lake	27-0034-00
Fish Lake	19-0057-00
Gervais Lake	62-0007-00
Hiawatha Lake	27-0018-00
Johanna Lake	62-0078-00
Keller Lake (Main)	62-0010-02
Lake Of The Isles	27-0040-00
McCarron Lake	62-0054-00
Medicine Lake	27-0104-00
Ryan Lake	27-0058-00
Taft Lake	27-0683-00
Unnamed Lake	62-0278-00
Wabasso Lake	62-0082-00
Wakefield Lake	62-0011-00

High risk streams in the TCMA
Link to this table

Streams	AUID
Bevens Creek	07020012-718
Bluff Creek	07020012-710
Classen Lake Creek	07010206-703
Clearwater Creek	07010206-519
County Ditch 17 (Spring Brook)	07010206-557
Credit River	07020012-517
Diamond Creek	07010206-525
Dutch Lake Outlet	07010206-678
Fish Creek	07010206-606
Painter Creek	07010206-700
Rush Creek	07010206-528
Unnamed Creek	07010206-704
Unnamed Creek	07010206-740
Unnamed Creek (Pleasure Ck)	07010206-594
Unnamed Stream (Perro Ck)	07030005-612
Unnamed Stream (Sand Ck)	07010206-744
Unnamed Stream (Trib To Long Lk) (Furgala Creek)	07030005-765
Unnamed Stream In Plymouth	07010206-738
Unnamed Stream Receiving Wtr From Medicine Lk	07010206-785