How road salt led to poisoned water in Flint, MI

.
It's time to recognize that spreading too much salt in Madison could have dangerous and unforeseen consequences.

In Flint, MI, road salt played a role in poisoning the public water supply.  When Flint switched the source of its water from Lake Huron to the Flint River, salt in the city's water soared from from 11.4 mg/l to 92 mg/l.  Salt in the river came largely from overuse of de-icing salt on roads.

Salt (chloride) is extremely corrosive.  It caused Flint's lead pipes to corrode, releasing lead that can cause brain damage in children.  At the home of Lee-Ann Walters and her 3-year-old son, average lead levels were measured at 2,000 ppb, sometimes exceeding the EPA criterion for "toxic waste."

Despite the increase in salt, the city did not add a corrosion inhibitor* to the water as many cities do. So both iron and lead pipes corroded, resulting in lead poisoning of many children.

Could Flint's poisoned water happen here?

Our situation is different, because Madison has replaced all its lead plumbing.  But three of Madion's shallower wells are becoming contaminated with salt (up to 37 mg/l in 2013).   The level of chloride in Lake Wingra is 130 mg/l and headed upward.  MG&E has been pumping millions of gallons of salty water into the ground with the Odana Project.

Even without lead pipes, chloride in city water can cause big problems.  The chloride corrodes iron pipes and water mains.  Flint has reported increased leaks--the corrosive water will cost millions of dollars in damage to pipes.  And when iron pipes corrode, they use up chlorine added to the water to kill bacteria.  That's why Flint had bacteria in their water--chlorine was rapidly used up after leaving the wells, leaving the water reaching consumers unprotected.

Madison's older water mains can rust from the inside and the outside. Chloride in both tap water and groundwater has been steadily increasing. Madison needs to replace half of its 400 miles of pipe.  By 2020, the annual cost of replacing or relining Madison's water pipes will be $12.7 million.

While the US does not consider chloride to be a pollutant, Canada does consider it "toxic," based on potential damage to the environment.  How long before Madison's salt reaches crisis levels? We already know salt causes billions of dollars in property damage, rusting autos, corroding bridges, and weakened parking ramps.  Now Flint demonstrates salt can have dire and unpredictable health consequences.  Our leaders should lead by taking decisive action to limit salt. 

Sources

How corrosion of iron pipes reduces chlorine

Details on effects of salt on Flint's tap water

Chloride in Madison's tapwater See p. 3. The median level of chloride in Madison's wells is 24 mg/l, ranging from 2.2 to 106 (2013).

* A corrosion inhibitor has been rejected by Madison's Water Utility, because it contains phosphorus which would also harm our lakes and streams.