With the arrival of warmer temperatures, Minnesotans may be putting their bags of de-icer into storage. But all the salt they sprinkled on the ground all winter in the name of safety?

It's hanging around.

In fact, it'll be here in July — and much, much longer than that. The sodium chloride, or salt, in most de-icers is now running off into lakes and streams with the meltwater, and it does not break down or disappear. And with no good way to treat it, the chloride has been accumulating in Minnesota's waters, slowly poisoning them.

About 50 Minnesota lakes and streams are now officially listed as impaired for chloride, meaning they don't meet water quality standards. Most are in the metro area. More are getting close to the limit. "It's a one-way street," said Sue Nissen, an Edina resident with a citizens' group called StopOverSalting (SOS). "I think that's what's alarming about it."

Concerned about this emerging pollution problem, state lawmakers are devising a new way to break Minnesota's winter salt habit. Bills currently in House and Senate committees would create a statewide program to certify the professionals who apply salt to sidewalks and parking lots, so they know how to best control ice without using excessive salt. The certification would cost individual contractors up to $350.

The bills target private snow and ice control companies who contract with property owners and managers. The measures are designed to help shield contractors from the threat of lawsuits, saying that certified applicators are not liable for damages from hazards resulting from accumulated snow or ice as long as they used "best management practices" for de-icing.

Addressing the fear of liability is crucial to changing the salt culture, said Brooke Asleson, a water pollution prevention coordinator for the Minnesota Pollution Control Agency (MPCA).

"The fear of slip-and-fall lawsuits is really a big barrier for them," Asleson said.

Homeowners out sprinkling their steps are not a significant source of the state's growing chloride contamination, said Asleson, and are not part of the bills.

Whether the liability protection is sufficient isn't clear. The bills also specify that liability isn't limited if the person applying the salt is negligent or should reasonably have known there was a dangerous condition, for example.

Joel Carlson, chief lobbyist for the trial lawyers group Minnesota Association for Justice, said his group supports the measures and worked on the clarifications.

"I can't think of a single instance where lowering someone's responsibility for polluting the environment has resulted in the outcome that you want," he said. "That just doesn't work."

The bills also don't address water softeners, the other main source of chloride pollution, said Rep. Peter Fischer, D-Maplewood, lead author of the House bill.

Cutting down on road salt alone won't solve the chloride contamination problem, but "it starts getting at it," Fischer said.

Forrest Cyr, government affairs director for the Minnesota Nursery and Landscape Association, has testified in support of the proposals. Cyr said he knows his members oversalt. They are under pressure, he said, from property owners and managers concerned about safety and mindful of negligence lawsuits. Owners want to see the salt, Cyr said.

"You can see the salt even on dry sidewalks," he said. "They put that down there just so there's no doubt in anyone's mind. It almost looks like snow."

Just check your shoes

Testifying at the State Capitol recently, Tim Malooly, owner of Irrigation by Design in Minneapolis, suggested committee members check their shoes for salt damage. They all looked down, he said.

Malooly said that while he hasn't been sued, he knows many vendors who have. The pressure is real, he said.

And it's grown in recent years as more people move into low-maintenance or no-maintenance communities, he said, such as senior developments. Residents hammer volunteer leaders in those communities with phone calls and e-mails when walkways get icy, he said. They want pristine sidewalks and driveways.

"They say: "Get out here and salt!' " Malooly said.

Limiting liability is crucial to getting buy-in, he said: "It gives us a great deal of cover to be able to reasonably stand up to the misunderstanding of some of our customers that want us to over-apply."

The new program would build on the MPCA's existing Smart Salting program, which focuses only on the Twin Cities. The expanded program would cost an estimated $200,000, including one new full-time position to run it.

The change can't come fast enough, some say.

"We have 10,000 reasons why we need that legislation," said Connie Fortin, president of Fortin Consulting, an environmental consulting company in Hamel. Fortin's company works with government agencies, and provides the training for the Smart Salting program, funded mostly with grant money.

Excessive chloride is toxic to fish and aquatic life, including bugs.

Saltwater is heavier than the freshwater. In lakes, it sinks to the bottom and creates a layer that can interfere with the way lakes naturally turn over their water, Fortin said, with water from the bottom moving to the top and stirring up oxygen.

"I don't think we've even begun to understand what that means for our lakes," Fortin said. "That's all new for us."