Fear for water

May 1, 2015

Minneapolis takes hard look at chloride in lakes, streams

The Minnesota Pollution Control Agency (MPCA) is charged with protecting the waters of our state.

We have 11,842 lakes and 92,000 miles of river. We not only love our water but we use our water. One out of six of us owns a boat, 900,000 are registered each year and with our 158 species of fish, we fish! In fact, over 1 million fishing licenses are sold each year, the most of any state. The fish stories also abound but that is not what we are here to write about. We have a problem. With the cold and snowy Minnesota climate and our high density of roads, parking lots and sidewalks, we have seen an increase in the salinity of our lakes, rivers and groundwater. Much of it is due to the large amount of road salt applied during the winter.

This is not a problem unique to metropolitan Minnesota, but a problem we share with many other cold-weather states and countries. 

Our traditional approach to addressing water pollution has been to monitor a waterbody and if it exceeds our standard for one or more pollutant it would be placed on the federal list of impaired waters, where we then develop a plan to meet the water-quality goals. Considering that this is a metropolis-wide issue and the long-term negative water-quality impacts that chloride has on the environment, we are trying a different approach. We are moving forward in developing a plan to protect all the lakes and rivers in the Twin Cities metropolitan area from chloride. We are looking beyond what we usually do, beyond what we have ever tried to do, to come up with a systematic approach to keep the roads safe and the waters clean.

78% is staying put

There are about 950 lakes and 9,600 miles of streams in the Twin Cities metropolitan area (TCMA), and 60% of the state’s population lives here. We have learned that approximately 75% of the chloride entering our waters is due to salt, and the remaining 25% is from nonroad-related sources such as wastewater-treatment facilities discharging the chloride used for water softening in the TCMA. Chloride is the primary pollutant in road salt that is toxic to the fish and bugs living in our waters. To help us better understand the current water-quality conditions with respect to chloride, we have spent the last several years compiling research and data, reviewing existing data and collecting additional water-quality data. 

A University of Minnesota study determined that 78% of the chloride applied through road salt is staying in Minnesota waters. This means our lakes, wetlands and groundwater are building up with chloride every year; it is not flushing out and moving down river. It also was estimated through salt-purchasing records that collectively we are applying approximately 365,000 tons of road salt each year in the TCMA. This was enough information for us to move forward with a project to determine how to address this very complicated and important issue.

We have gained some important insights about how chloride interacts with our waters. First is that how, when and where we collect chloride samples is important to getting the full picture. For instance, in streams it is critical to collect water-quality samples in the winter months when we have thaw events occurring. This is when we see the highest concentrations of chloride. It also is important to get chloride samples in summer to track the groundwater contributions to the stream. Without this critical information we would underestimate the water-quality implications of salt. We have found that our lakes tend to have higher concentrations of chloride in the bottom part of the lake versus the surface. In some of our lakes, just looking at the surface data alone would indicate that we are meeting the state’s water-quality standard, but the deep sample indicates otherwise. 

We also learned a bit more about the distribution of salt application rates across the TCMA and broke this down by state, county, municipal and commercial. This work was part of a feasibility study completed in 2009. As part of this study we also evaluated the current research regarding the impacts of road salt on the environment. The full report can be found at our website: www.pca​.state.mn.us/nwqhcf6.

To help us get a clearer understanding of the TCMA water-quality conditions we have coordinated with several of our local watershed partners to begin a targeted chloride monitoring effort. This effort includes 74 lakes, 27 streams and eight storm sewers and began in 2010. Selected locations were based on road density, existing data near standard, lake and stream characteristics and availability of partners. This monitoring effort has three objectives: to assist the MPCA in developing new monitoring guidance specifically for chloride; to improve the chloride database for the TCMA; and to inform the development of the TCMA Chloride Management Plan. We will conclude our final year of targeted chloride monitoring this spring (2013) and will follow that with an evaluation of water-quality conditions of all the surface waters in the TCMA. 

In the summer of 2013, we will complete a final evaluation of all the surface waters in the TCMA and determine which waters are above the allowable limit of chloride and which are below. This evaluation, also known as the impaired waters assessment, will determine which waters will require a total maximum daily load (TMDL) study versus a protection strategy. Those waters that are already above the allowable limit of chloride will have goals that will be required to be met through a permit. 

There have been two TMDL studies completed for chloride within the TCMA already—Shingle Creek and Nine Mile Creek—which both required a 60-70% reduction in salt use in their watersheds. We have been using those projects as examples for us to learn from. We are expecting at least 30 or more waters to be in violation of the chloride standard.

Once the formal evaluation is complete, we will have a clearer understanding of the water-quality conditions in the TCMA and we will use that information to assist us in developing goals that will need to be met in order to maintain healthy surface waters. Water-quality goals will be set for all surface waters in the TCMA so that we can protect those waters not yet polluted. It is much more cost effective to prevent a lake or stream from becoming polluted than it will be to clean up the water. For this reason we will not only set goals and develop a plan for the waters that are above the state’s chloride standard, but also set goals for all other waters. 

There are a significant number of surface waters in the TCMA where we will not have water-quality data, but we want to be protective of those waters as well. The amount of time it would take to collect sufficient chloride data on all surface waters in the TCMA would be too late for most of our waters. So moving forward to protect all waters is an important component of this effort and one that we will see great benefits from. 

But setting water-quality goals is only half of the picture. We also need to have a better understanding of all of the sources of chloride to our waters. The more detailed information we get, the better we will be able to know what we will need to do to meet our water-quality goals. We already know that 75% of the chloride is coming from salt, but we will need to split that further into specific applications and accurate amounts being used. We also will be investigating the contribution from other sources as well to ensure we are addressing all the chloride sources possible. Understanding the current water-quality conditions and the sources of chloride is critical to taking the next step of setting the goals needed.

Handing you a tool

Setting the necessary goals and the associated reduction targets is the next step in our project. We have put together a comprehensive stakeholder process that is intended to develop strong partnerships between the environmental organizations and the winter-maintenance industry. Our goal is to have the process of developing our plan to address the water-quality impacts of road salt be driven by our winter maintenance and local water resource partners. 

One of our key partners on this project is the Minnesota Department of Transportation (Mn/DOT). This partnership is key to a successful outcome, as they are leaders in winter maintenance in Minnesota, and their expertise, experience and dedication to protecting the environment are critical. We are working with several experts in the industry to help us find a realistic path to meeting our needed water-quality goals. In most cases we are expecting a need to reduce the amount of salt used, so working closely with the applicators is key to ensure that we are not compromising public safety.

In order to help winter-maintenance organizations meet the salt targets, we are in the process of developing a winter-maintenance assessment tool. In the past we often assigned a laundry list of best practices and suggested that everyone follow this list. However, we realize that in the complex world of winter maintenance, one size does not fit all. So we are trying something new. We are developing a tool that will allow the organization to generate its own list of best practices that will guide it toward water protection. Fortin Consulting Inc. is spearheading this part of the project for the pollution-control agency. The tool design will be completed in 2014 and out for use no later than 2015. Meanwhile, a technical expert group is working closely with Fortin Consulting to explain the many issues involved in winter maintenance. 

The tool will ask about 125 questions about many areas of winter maintenance, and the user will select the answer that best represents their practices both today and in a five-year projection. Answers are color-coded to show excellent, good and bad practices. Reports will be generated to help organizations see if they are lagging behind, operating as expected or leading the industry. 

We also are trying to integrate “salt-savings” predictions into the tool. So as you indicate where your organization plans to change, the tool can give you a rough estimate on the salt you would save by making that change. 

In Minnesota we are fortunate to have great lakes and rivers but also that the environmental community and maintenance professionals have come to know and respect each other. As you can imagine, it is easy to agree on the common goal of safe roads and clean waters. But the difficulty lies in creating the changes necessary in winter maintenance that will allow us to reach our goal. 

The MPCA has and will continue to encourage change in winter maintenance. The winter-maintenance assessment tool is a good example of this, but the power to protect our water lies in the hands of the winter-maintenance professionals. 

For more information about the TCMA chloride project contact Brooke Asleson at [email protected] or visit our website at www.pca.state​.mn​.us/r0pgb86 

For more information about the winter maintenance assessment tool contact Connie Fortin at connie@fortinconsulting​.com. WM

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