What Road Salt Does to Rivers
The District has taken a degree of crap over the last couple of months for dumping tons of salt on the roads, only to see minimal snowfall. Seeing berms of salt develop on city streets reminded me of Seattle two years ago, where officials were concerned enough about the negative environmental effects of snow on surrounding bodies of water that they used sand instead. This didn't work out too well either; the grit stayed for months, casting a brown haze over the city and not doing much for road safety either (it's no accident that the mayor got voted out in the next election). Still, it made me wonder: Isn't all this salt kind of bad for the rivers D.C. sits on?
I posed the question to the Anacostia Watershed Society, which answered that yes, it does have negative effects. The above graph shows spikes in "conductivity," which is an indication of salinity, in the Anacostia at Riverdale, Maryland. Sure, this is upstream from D.C.'s runoff, but the spikes correspond directly to the times when everybody was salting their roads in advance of storm warnings. Many forms of aquatic life don't do well in brackish water; tadpoles die in concentrations above 6,000 microsiemens per centimeter, which was reached on January 18th. Last year, Slate explained that even though the damaging effects of road salt are pretty well-known, cities still use it because it's cheap.
You can understand DDOT's position here: They can't help it if all signs point to snow, they salt the roads, and it ends up being for naught. They're also doing what they can to reduce the amount of salt needed by pre-treating the roads with beet juice and brine. So far this year, that's still come out to 24,000 tons of sodium chloride on the roads and in the river (last year, the total was 85,000 tons). The District Department of the Environment apparently did a study on alternatives, finding that something called IceBan is the safest deicer. If we're serious about cleaning up the Anacostia, it would be nice to see it at least considered.
UPDATE, Saturday, 8:20 a.m. – AWS' water specialist Masaya Maeda brings up a good point: IceBan may be better for the environment, but it's not cheap. The better solution would be for more people to just work from home when snow hits, so that road crews can clear snow mechanically. And of course, it's always easier when people live near enough to their workplace to walk there, rather than driving in from the suburbs.