Salt on the roads: Good for safety, bad for environment

The thousands of tons of salt that made roads passable this week have not reached their final destination, nor had their final effect. As the snow melts, the salt will be flowing into storm drains and beyond, adding to the steady salting of the region's waterways.

Over the last 60 years - pretty much since regular use of sodium chloride on roads began - the annual average sodium concentration in the Delaware River has nearly tripled and chloride has increased fivefold, researchers have found.

At times, sodium concentrations at the Philadelphia Water Department's intakes already exceed American Heart Association and U.S. Environmental Protection Agency "guidance levels."

Because the department, like many others, can switch intakes and mix in water with lower salinity, the final product contains lower levels, said Chris Crockett, director of planning and research.

If current trends continue in the coming decades, however, experts say that aquatic life will suffer and water supplies could be threatened. Sodium is a concern for people with medical conditions such as hypertension.

"This cannot go on indefinitely. It is not sustainable," said Jonathan Husch, chair of Rider University's department of geological, environmental and marine sciences, which has been researching salt issues locally.

Just since Sunday, PennDot has spread 8,000 tons of salt in Southeastern Pennsylvania. The City of Philadelphia put out an additional 7,000 tons. Hundreds of smaller municipalities, thousands of businesses, and millions of residents tossed more.

Unlike the pollutants that are typically removed by water-treatment plants, getting the salt out can require entirely different technologies such as reverse osmosis.

Eventually, said Crockett, governments may need to decide on which end of the process to spend precious public funds: more environmentally friendly deicers for the roads or new treatments for the water. Both cost more.

Officials - especially those in more northern areas - have been aware of the problems with salt for more than a decade. But it's only been in the last few years, with increased public focus on the environment, that significant innovations have emerged.

Highway crews in both Pennsylvania and New Jersey, for example, have been spraying ahead of time with a salty brine solution. The liquid - look for the stripes down the lanes before a storm - stays on a bare road better than salt, it delays the formation of ice and, when salt is spread later, it speeds melting.