Minnesota's Chloride Management Plan: Reducing Chloride Impacts on Water Quality and Costs, Lecture notes of Technology

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Minnesota Statewide

Chloride Management Plan

Acknowledgements The development of this plan was accomplished through a partnership approach with many agencies and organizations across the state. Their contribution to this plan and commitment to the issue has allowed us to develop this comprehensive and strategic approach to reducing salt use while maintaining public needs. Significant Contributors: The MPCA contracted with Fortin Consulting, Inc. to provide the necessary research, civic engagement efforts, and development of statewide winter maintenance best management practices (BMPs) for inclusion in the Statewide Chloride Management Plan and Smart Salting Assessment Tool (SSAt). Fortin Consulting also assisted in the development of many sections of this plan and provided critical review throughout its development. This work was funded through State Clean Water Funds. The MPCA contracted with LimnoTech to provide the necessary research, data analysis, and development and review of many sections of the plan. This work was funded through State Clean Water Funds. Partnerships: American Public Works Association - Minnesota Chapter Bassett Creek Watershed Management Commission Becker County Big Stone County Board of Soil and Water Resources Capitol Region Watershed District Carver County Casper Construction Chippewa County City of Burnsville City of Cohasset City of Detroit Lakes City of Duluth City of Fargo City of Grand Rapids City of Granite Falls City of Hermantown City of LaPrairie City of Luverne City of Marshall City of Minneapolis City of Montevideo City of Moorhead City of Nisswa City of Pipestone City of Plymouth City of Red Wing City of Redwood Falls City of Rice Lake City of Rochester City of Sartell City of Shoreview City of St. Cloud City of St. Paul City of Superior City of Willmar City of Waconia City of Wadena Clay County Crow Wing County D & G Excavating Inc DeSaer Outdoor Creations

Table of Contents

Figure 18: Minnesota Average Winter Daily Minimum Temperatures ...................................................... 35 Figure 19: Minnesota Average Annual Precipitation, 1895- 2015 ............................................................... 36 Figure 20: Chloride Condition in TCMA Surface Waters ............................................................................. 49 Figure 21: Comparison of lakes and wetlands in the TCMA ....................................................................... 50 Figure 22: Comparison of streams in the TCMA that are listed on the MPCA’s 2018 Impaired Waterbodies list. ......................................................................................................................................... 51 Figure 23: Comparison of high risk lakes in the TCMA that are not listed on the 2018 Impaired Waterbodies list. ......................................................................................................................................... 52 Figure 24: Comparison of high-risk streams in the TCMA that are not listed on the 2018 Impaired Waterbodies list. ......................................................................................................................................... 53 Figure 25: Chloride Conditions in Statewide Minnesota Surface Waters. The concentrations of all high risk waterbodies (the lakes, wetlands, and streams with at least one chloride measurement within 10% of 230 mg/L within the last 10 years) and those waterbodies with an exceedance of 230 mg/L .............. 55 Figure 26: Comparison of statewide lakes outside of the TCMA that are listed on the 2018 Impaired Waterbodies list or are of high risk. ............................................................................................................ 56 Figure 27: Comparison of statewide streams outside of the TCMA that are listed on the 2018 Impaired Waterbodies list or are of high risk. ............................................................................................................ 57 Figure 28: Map showing temporal trends in chloride concentrations in Minnesota’s groundwater, 2005-

2017. ........................................................................................................................................................... 63 Figure 29: Chloride concentrations in ambient groundwater from the sand and gravel aquifers ............. 64 Figure 30: Chloride Trends (Demuth and Scott 2020) ................................................................................ 65 Figure 31: Distribution of Monthly Surface Cl Concentrations in Lakes Normalized by Total Mean Lake Concentrations. ........................................................................................................................................... 67 Figure 32: Monthly average chloride concentrations in Powderhorn Lake (27- 0014 - 00). Surface concentrations were significantly less in January and February (Wilcox Mann Whitney test, p < 0.05). .. 67 Figure 33: Monthly average chloride concentrations in the Buffalo River (09020106-501) in the South Fork Crow River Watershed ........................................................................................................................ 68 Figure 34: Monthly average chloride concentrations in Battle Creek (07010206-592) in St. Paul. ........... 68 Figure 35: Monthly chloride concentrations (average, maximum, and minimum) in Sand Creek ............. 69 Figure 36: Monthly chloride concentrations (average, maximum, and minimum) in Beaver River (04010102-501)........................................................................................................................................... 69 Figure 37: Trend Analysis for % Increase in Chloride Concentration per year in TCMA Surface Waters (Lakes) with at least 10 years of data. ........................................................................................................ 72 Figure 38. Increasing chloride concentration in surface samples in Gervais Lake from 1983-2016. ......... 73 Figure 39: Trend Analysis for % Increase in Chloride Concentration per year in Minnesota Lakes with at least 10 years of data. (Excluding the TCMA) ............................................................................................. 74 Figure 40. Increasing chloride concentration in surface samples in Zumwalde Lake (73- 0089 - 00) from 1978 - 2009. .................................................................................................................................................. 75 Figure 41. Increasing chloride concentration in surface samples in Horseshoe Lake (73- 0157 - 00) from 1978 - 2009. .................................................................................................................................................. 75 Figure 42. Average monthly chloride concentrations in surface and subsurface samples in Brownie Lake (27- 0038 - 00) ............................................................................................................................................... 76 Figure 43. Average monthly chloride concentrations in surface and subsurface samples in Peavey Lake (27- 0138 - 00) ............................................................................................................................................... 76

Figure 44. Average monthly chloride concentrations in surface and subsurface samples in Spring Lake (27- 0654 - 00) ............................................................................................................................................... 77 Figure 45: Seasonal patterns of salt accumulation and flushing. (Photo courtesy of Dr. Jacques Finlay at 2019 Annual Salt Symposium) .................................................................................................................... 78 Figure 46: Salt inhibits mixing of Stormwater ponds. (Photo courtesy of Dr. Jacques Finlay at 2019 Annual Salt Symposium) ............................................................................................................................. 78 Figure 47: Diagram of potential impacts of increased chloride concentrations to stormwater ponds. (Photo courtesy of Dr. Jacques Finlay at 2019 Annual Salt Symposium) .................................................... 79 Figure 48: Long Term Water Quality Trends at Minnesota Milestone Sites - Chloride .............................. 80 Figure 49: Long-Term Water Quality Trends at 80 Minnesota Milestone Sites ......................................... 81 Figure 50: Flow-Adjusted Chloride Concentration Trends in the Mississippi, Minnesota, and St. Croix Rivers, 1985- 2015 ....................................................................................................................................... 82 Figure 51. Winter chloride concentrations (November-March) in TCMA lakes versus Osgood Index (p <0.05) .......................................................................................................................................................... 84 Figure 52: Relationship between road salt load and median winter stream chloride concentration. (Wenck 2009) .............................................................................................................................................. 85 Figure 53. Relationship between road density and median winter chloride concentration. (Wenck 2009) .................................................................................................................................................................... 85 Figure 54. 2010 Road Density in the TCMA ................................................................................................ 86 Figure 55. 2010 Statewide Road Density: (Road density from MPCA based on roads from MnDOT and catchment watersheds from DNR) ............................................................................................................. 87 Figure 56: Ecoregions and Land Cover in Minnesota .................................................................................. 88 Figure 57. Storm sewer monthly chloride concentrations ......................................................................... 89 Figure 58: Mean monthly loading of chloride (lbs.) by flow regime (snowmelt vs. rainfall-runoff) observed at Alameda Pond Inlet over two years of continuous monitoring from Aug 1, 2015 to Jul 31, 2017 (Herb 2017). ....................................................................................................................................... 90 Figure 59. Chloride in Surface and Ground Water in the TCMA ................................................................. 91 Figure 60. Chloride and Road Density in the TCMA .................................................................................... 92 Figure 61. Increasing chloride concentrations in Eagle Creek from 2001- 2017 ......................................... 93 Figure 62. Average chloride concentrations (July-October) in Shingle Creek from 1996- 2017 ................. 94 Figure 63. Watershed with road densities 18% and greater in Minnesota .............................................. 107 Figure 64. Watershed with road densities 18% and greater in Southern Eastern Minnesota ................. 108 Figure 65. Watershed with road densities 18% and greater in Northeastern Minnesota ....................... 109 Figure 66: Prevalence of Minnesota communities with WWTPs having Reasonable Potential ............... 110 Figure 67: Annual chloride (tons) estimated from potash sales by district (Aicam 2020)........................ 111 Figure 68: General performance-based timeline for chloride management, applicable to all stakeholders. .................................................................................................................................................................. 112 Figure 69: Chloride Decision Tree for implementing Minnesota’s chloride water quality standard in wastewater discharge permits (MPCA 2017). .......................................................................................... 127 Figure 70. Cost Considerations Related to Salt Use .................................................................................. 166 Figure 71: City of Morris Water Treatment and Central Softening Facility .............................................. 172 Figure 72: Ventrac Salt Drop Spreader Used by Edina Public Schools ...................................................... 186 Figure 73: Precision Landscaping Brine Truck ........................................................................................... 189 Figure 74: City of Waconia Truck capable of dry/liquid material mix application. ................................... 197

Acronyms AUID Assessment unit identification BMP Best management practice BWSR Board of Water and Soil Resources CaCl (CaCl 2 ) Calcium Chloride CFR Code of Federal Regulations CMP Chloride Management Plan DNR Minnesota Department of Natural Resources EOC Education Outreach Committee EPA Environmental Protection Agency EQuIS Environmental Quality Information System gpg grains per gallon IPP Industrial Pretreatment Program KCl Potassium chloride LA Load allocation lb pounds MCES Metropolitan Council Environmental Services MgCl (MgCl 2 ) Magnesium chloride mg/L milligrams per liter MCWD Minnehaha Creek Watershed District MnDOT Minnesota Department of Transportation MPCA Minnesota Pollution Control Agency MPRB Minneapolis Park and Recreation Board MS4 Municipal Separate Storm Sewer System MSG Monitoring Support Group MWMO Mississippi Watershed Management Organization NaCl Sodium chloride NMCWD Nine Mile Creek Watershed District NPDES National Pollutant Discharge Elimination System RO Reverse osmosis RWMWD Ramsey-Washington Metro Watershed District SSAt Smart Salting Assessment tool SWCD Soil and Water Conservation District TCMA Twin Cities Metropolitan Area (Anoka, Carver, Dakota, Hennepin, Ramsey, Scott, Washington) TMDL Total Maximum Daily Load USGS United States Geological Survey WD Watershed District WLA Wasteload allocation WMO Watershed Management Organization WTP Water Treatment Plant WWTP Wastewater Treatment Plant

Executive Summary: What is the Statewide Chloride Management Plan? Reducing chloride at the source is needed throughout the state of Minnesota, not only to restore already impacted waters but also to protect all water resources. Chloride is persistent in the environment, and once it there, is difficult to remove. This also means that chloride will continue to accumulate in the environment over time. There are multiple sources to consider, a variety of options to reduce chloride, and a large geographical area to address. A main purpose of this plan is to provide guidance, resources, and information to individuals and organizations in assisting with making the important decisions of the what, how and when for managing chloride. The Minnesota Pollution Control Agency (MPCA) has partnered with local partners, other state agencies, and experts across the state to create a plan for effectively managing salt use to protect our water resources in a responsible and strategic approach. Solutions were developed collaboratively to find a balance between clean water and salt use. The Statewide Chloride Management Plan (CMP) incorporates water quality conditions, sources of chloride, salt reduction strategies, protection strategies, water quality monitoring recommendations, and measurement and tracking of results. The goal of this plan is to provide information and strategies to assist local partners in reducing salt at the source while providing safe and desirable conditions for the public. There are several sources of chloride impacting the state’s water resources including: salt applied to roads, parking lots, and sidewalks for winter maintenance; water softener brine discharges to municipal wastewater treatment plants (WWTPs) and septic systems; industrial discharges; agricultural fertilizers; land application of manure and WWTP sludge; and dust suppressants. The MPCA collaborated with multiple state agencies, local partners, and experts across the state to develop a plan to reduce chloride and protect Minnesota’s waters. This Statewide CMP incorporates water quality evaluation, source identification , implementation strategies , monitoring recommendations, and measurement and tracking of results into a performance-based approach for the state of Minnesota. The Minnesota Statewide CMP is intended to characterize water resources across Minnesota and the overall impacts of chloride. This plan is an adaptation of the Twin Cities Metropolitan Area (TCMA) CMP, which was published in 2016 (TCMA CMP 2016). The TCMA CMP was developed to address the major chloride concerns within the Twin Cities and surrounding counties, and paid particular attention to the role of winter maintenance Figure 1 : Timeline of Statewide Chloride Management Plan Implementation

approach doesn’t focus on specific numbers to meet, but rather on making progress through the use of BMPs. Progress is measured by degree of implementation and trends in ambient monitoring. The purpose, scope and audience for the CMP are presented in Figure 2. Prioritization and Critical Areas: Where Do I Start? Organizations interested in reducing the amount of chloride entering our water resources should begin with an effort to fully understand the problem and determine what role the organization plays in contributing, preventing, or slowing the growing trend of increased chloride in surface and groundwater. Road salt and water softening are two large statewide sources of chloride in the environment and many of the current reduction strategies focus on these two sources. This plan also identifies critical watersheds and locations around the state based on road density and potential demand for water softening, where chloride loadings are to be expected high and therefore implementation efforts to reduce chloride should be focused. For the protection of surface and ground waters implementation is encouraged statewide. Know what the primary sources of chloride are in your community. Consider your organization’s relationship with the primary sources of chloride in your community. Understand local water resources and conditions, both surface water and groundwater. Addressing these considerations can help determine priorities and critical areas. Implementation Strategies The statewide CMP provides the overall framework for the implementation strategies that are necessary to protect and restore our water resources. Section 5 of this plan provides the implementation activities for specific audience and all sources of chloride. The over-arching implementation strategy is a performance-based approach. This approach allows stakeholders and regulators flexibility in the type of BMPs and the timing of implementation, and allows individuals an opportunity to develop specific chloride management strategies that are practical for their individual situation. Success under the performance-based approach is measured in terms of the progress made and BMPs implemented. Local priorities should be set with a plan in place within 1 to 2 years after this Statewide CMP is published. Local priorities will vary by various stakeholder groups and audiences. By years 3 to 5, an implementation plan should be set and successes and progress should begin to be monitored. Years 6 to 10 should be spent sharing successes and revising any necessary components of the localized plan. Find Your Section of the Plan This plan was developed to be used by many different audiences and organizations. Every organization will have different priorities based on their local watershed conditions, the role of their organization in the watershed or state, and their organization’s specific needs or goals. Section 5 of the Statewide CMP lay out implementation strategies for how each person or organization can reduce chloride based on the types of activities with which they are involved. Example strategies and timelines are also provided as templates. Because the Statewide CMP is meant to be used as a reference document to assist you or your organization in chloride reduction, Section 5 may be the most useful section for you to revisit as you develop and implement chloride reduction strategies.

Figure 2 : Minnesota Statewide Chloride Management Plan - Purpose, Scope, and Audience 13 Minnesota Statewide Chloride Management Plan Purpose - Scope - Audience Purpose  Highlight the impacts of chloride on statewide water resources  Develop an understanding of the competing demands of level of service and reduced salt usage  Set performance-based goals for the protection and improvement of water quality  Inform and guide implementation of best practices and policies  Provide education, guidance, and resources to reduce chloride  Point out need for more research and development of additional Best Management Practices (BMPs)  Status and trends of chloride levels in Minnesota lakes, wetlands, streams, and groundwater  Identify statewide sources of chloride  Chloride reduction and protection goals  Implementation strategies to reduce chloride impacts  Educational and training resources  Continued monitoring, tracking, and adaptive management Scope Audience  Local government and working groups (Watershed Districts, Municipalities, SWCDs, WMOs, Townships, etc)  Winter maintenance groups (MnDOT, local governments, private applicators, commercial property owner, residents, etc)  Elected officials and policy makers  Permit holders  State agencies (MPCA, MnDOT, DNR, BWSR, etc.)  Any industrial users of chloride (Water Softening Industry Uses, Fertilizer Users)  Dust control applicators  Anyone using chloride containing products in MN

out of the TCMA via streamflow in the Mississippi, Minnesota, and St. Croix Rivers (Stefan et al. 2008). Therefore, 70% to 78% of the applied chloride remains in TCMA lakes, wetlands, and groundwater, and it may also be stored in soil pore-water where infiltration is slow. Chloride stored in this latter location may be slowly released in base flow throughout the year (Corsi et al. 2015). Since chloride is an element and does not breakdown over time, the high percentage retained suggests that chloride will continue to accumulate, some of which can eventually be transported to shallow and deeper aquifers. This also implies that, on average, chloride concentrations in waterbodies are increasing with time if there is an external loading source. It should be noted that although chloride is considered to be largely inert in soil, which contributes to its ability to readily mobilize, chloride can be immobilized in the soil through chlorination reaction with organic matter (Osswald et al. 2016). Figure 3 : Conceptual model of anthropogenic sources of chloride and pathways If the chloride loading remains steady, the concentrations will level out when equilibrium develops between loadings and transport out of a particular waterbody. By the same token, if loadings are reduced sufficiently and persistently, the chloride concentrations in the waterbodies will begin to decrease and will continue to decrease until a new equilibrium is reached. Each of these sources is briefly described below. A 2019 report by University of Minnesota (UNM) researchers, estimated chloride contributions from statewide sources. From a statewide perspective, de-icing salt use, fertilizers, and WWTP (residential, commercial, industrial softening and other sources of chloride in the influent) make up the predominant sources of chloride, shown in Figure 4 (Overbo et al. 2019). Although the data available for statewide purchases and uses of chloride products estimate that the statewide mass balance contribution of WWTPs and fertilizer application are roughly equivalent, we are seeing more chloride impaired water bodies in urban areas, and that in past completed TMDLs the predominant sources to water bodies impaired by chloride are from de-icing salt and municipal WWTPs in others.

It has been difficult to quantify the contribution of chloride loading from agriculture specifically as many times the groundwater and non-permitted sources (outside MS4 permitted areas) will contain both natural background chloride, chloride applied as winter and gravel road maintenance, as well as agricultural sources chloride. A source assessment of chloride sources that goes beyond MS4 and WWTP contributions can be difficult. At the time of the development of this document, the MPCA is developing a new chloride source assessment model that will allow Minnesota communities to evaluate their specific sources and magnitude of chloride, and provide guidance to develop a community specific chloride reduction plan. More information on this project can be found in Section 5.3 below. 1.1. Winter Maintenance Activities Winter maintenance activities include snow and ice management. Application of de-icing and anti-icing chemicals, primarily salt, is common. Salt is applied to a variety of surfaces including roads, parking lots, driveways, and sidewalks. Runoff from salt storage facilities is another potential source of salt. As an example, an estimated 17% of salt is lost by storing salt/sand piles uncovered over the winter. By implementing the recommended BMP of storing salt/sand piles indoors, there is an estimated 17% reduction potential for a pile. The St. Anthony Falls Laboratory at the UMN developed an inventory of salt uses in the TCMA for a MnDOT Local Roads Research Board study (Sander et al. 2007). The inventory estimated the total amount of salt used for winter maintenance activities in the TCMA, based on purchasing records, to be 349,000 tons per year. Estimates of use by various entities are shown Figure 4. More recent research through the Water Resources Center at UMN estimates that 403,600 tons of de- icing salt are used each season in Minnesota, and that 249,100 tons of de-icing salt are used in the TCMA (Overbo et al. 2019). Figure 5 is an adaptation from an article by Sander et al. in 2007 that provides a summarized distribution of road salt use in the TCMA per season between certain public in Figure 4 : Fraction of annual chloride contributions from major point and nonpoint sources for State of Minnesota (Overbo et al. 2019) _Please note that Road salt use is actually all de-icing salt applied to roads, parking lots, sidewalks, and trails._*

Roads

The state of Minnesota is estimated to have over 2 85 ,000 lane miles of roadways (MnDOT 2018). Application rates range from 3 to 35 tons of road salt, per lane mile, per year, based on the salt purchasing records and the number or lane miles of MnDOT, counties, and cities in the TCMA (Wenck 2009). The preferred level of service and possible seasonal closure of certain roads may affect this estimate in rural counties. A survey of municipal winter maintenance professionals in the TCMA, done by LimnoTech in 2013, found that typical application rates range from 100 to 600 pounds of salt applied per lane mile per event, which is consistent with previous evaluations of road salt application rates. However, rates can be much higher on hills, near intersections, and other ice problem areas. Higher speed roadways and those that experience high average daily traffic volumes will typically have greater applications rates. Some events may require multiple passes of salt application.

Commercial Parking Lots, Driveways, and Sidewalks

Commercial sources of deicing salt can vary greatly between different watersheds and includes salt applied to parking lots, driveways, and sidewalks on commercial property. The land owner or tenant may conduct winter maintenance activities, or winter maintenance may be contracted with private winter maintenance providers. Because of this, the MPCA has developed Smart Salting training and certification program specific to property managers. Commercial sources are likely responsible for 10 % and 20% of the total salt applied to paved surfaces in the TCMA and other urban environments (Wenck 2009). The MPCA and Fortin Consulting conducted research to validate and refine assumptions regarding commercial and private salt application rates specific to Minnesota (Fortin 2012a). There is a range of reported application rates, which is to be expected, because rates should vary based on temperature, type of snow event, surface to where material is applied, number of passes over an area during an event, and type of material used. Application rates of salt on parking lots are estimated to range from 0.1 to 1 ton per acre per event, and typically 6.4 tons per acre per year. For sidewalks, the application rate is estimated to range from 8 to 25 pounds per 1,000 square feet per event (0.2 to 0. tons per acre per event). Review of available information and additional research included application rates from across the United States’ and Canada’s Snowbelt, with an emphasis on Minnesota specific data. It was determined that an average rate of 6.4 tons per acre per event is the appropriate application rate to expect on parking lots. As a percent of the total deicing salt usage, it is estimated that anywhere between 5% and 45% is used for commercial applications (parking lots, sidewalks, residential, private roads). The amount of chloride from commercial sources is variable, and is dependent on the characteristics of the watershed, including the amount of impervious area. Additional estimates of commercial salt use are presented below.  The Nine Mile Creek Chloride TMDL report used data on salt purchases from Sander et al. (2007) and Novotny et al. (2008), but weighted the data based on land use. It was determined that the relative contribution for commercial and packaged deicer in the Nine Nile Creek Watershed was 38% of the total amount of road salt that is applied (Barr Engineering 20 10 ).

 In the Shingle Creek TMDL, it was estimated that 7.5% of salt application was by commercial/private applicators. This figure was based on the estimates used in Canada. “Cheminfo (1999) estimated that commercial and industrial consumers represented approximately 5% to 10% of the deicing salt market. In quantifying total deicing salt application in Canada, Environment Canada used the midpoint of these data (7.5%) to represent commercial and industrial salt application (Environment Canada 1999).” (Wenck 2006).  Sander et al. (2007) estimated that the bulk deicing salt applied by commercial snow and ice control companies accounted for 19% of the total salt used in the TCMA, while packaged deicer for home and commercial use was estimated to account for 5% of the total in the TCMA.  Novotny et al. (2008) used market share amounts from the USGS annual mineral reports and the market share report published annually from the Salt Institute. TCMA amounts were estimated based on national amounts combined with the commercial bulk (19%) and packaged (5%) deicer estimates for a total of 24%. o On a national basis, the Salt Institute estimated that 20% of bulk de-icing salt purchases were by non-governmental entities. o The USGS estimated 13% of ice control salt is for commercial use.  A chloride TMDL study in New Hampshire reported a chloride application rate of 5.7 to 6.4 tons per acre per year for parking lots and drives (Sassan and Kahl 2007). Parking lots were 47% of paved surfaces in the watershed and accounted for 36% of the chloride load. The study also estimated that 45% of salt was applied by private applicators.

Residential Parking Lots, Driveways, and Sidewalks

Residential winter maintenance can also be an important chloride source. Residential winter maintenance salt use has been estimated from purchasing records. Packaged deicer for home and commercial use is estimated to account for 5% to 7 % of the total in the TCMA (Novotny et al. 2008) A Sidewalk Salt Survey was conducted to qualitatively assess the use of sidewalk salt by the general public in the TCMA. The survey was disseminated by local partners including RWMWD, MCWD, and MnDOT. The survey was administered through an on-line Survey Monkey link on the MCWD website (www.minnehahacreek.org) from November 2011 through March 2012. The survey was completed by 606 people online and 148 completed a paper survey. Approximately 47% of the respondents lived in St. Paul or Minneapolis, and other respondents lived in surrounding cities including Woodbury, Richfield, Plymouth, and Maplewood. Although the survey sampled 754 residents, the results represent a small percentage of the TCMA population and are non-random/voluntary; therefore, the survey is not representative of all residents in the state of Minnesota. However, the data provide valuable information on the use of sidewalk salt by a subset of Minnesota residents. The majority of residents that responded to the survey used sidewalk salt (57%), particularly on sidewalks and steps. Most people selected products based on performance in colder temperatures and environmental safety. The majority of respondents did not know how much sidewalk salt to use (59%). The majority of respondents that applied salt used instruction on the packaging as guidance for application rates. For complete results of the survey see Appendix B.