"Unsustainable" means... "change is coming." And, you might not like the form change takes.
By the time people start talking about the sustainability of something--like spreading salt on streets--you can bet it's been going on for a long time. And, you can bet there's a good reason why people don't want to change. So, sustainability issues always involve tough choices. And if we don't make those tough choices, then reality forces change upon us.
Salt on roads
Take de-icing salt as an example--as practiced by the Madison. Salt use began in 1959. By 1973 it was recognized as a problem, and by 1977 the city set a target for the maximum amount to be spread in any winter. But salt use continued to rise more or less steadily. For the last decade, we've exceeded that target by 265%. So, for 34 years, we've been failing to solve the salt issue.
Meanwhile, the salt levels in all of Madison's lakes have continued to climb, while salt levels in half the city's wells are trending higher. Three of the wells exceed levels of salt recommended for people on low-salt diets. Scientists warn that if these trends continue, there could be widespread damage in aquatic ecosystems. But they can't say exactly when or how that damage will occur. It's like our own local version of the climate debate.
Each city administration tinkers with some technical adjustments to the salt spreading machines, while kicking most of the problem down the road to the next administration. So, do we just wait around for the universe to lower the boom on us, in some unpleasant way? Or do we decide for ourselves how we want to avert whatever unpleasant future might be lurking?
If only there were some clear cut menace waiting down the road, it would be easier to take action. But probably, the "end of sustainability for salt" won't arrive with trumpets and lightning. Instead, with a little imagination, here's what could happen.
Our bridges rust away until, combined with other severe economic pressures, the city finds them too expensive to repair. Cars become more expensive to operate, because of the increasing cost of fuel, added to heavy depreciation from rust--caused by road salt. So tourists stay home, and we lose all that revenue. And, people also stay home because the fish are floating belly up in our lakes. As wells become more salty, the city defends against expensive lawsuits from people whose health has been harmed, and then millions more are spent to drill deeper wells.
The end to salt finally comes when a bankrupt city simply finds it too expensive to send out fleets of trucks every winter to spread the stuff. If only we had saved the money spent on salt, BEFORE all that corrosion and environmental damage bankrupted the city.
Here's something to think about. This problem is a ticking bomb, because groundwater flows very slowly. More than half the salt makes its way into the groundwater. The groundwater is a giant reservoir that dilutes all the salt, and makes it seem less of a problem. The pure groundwater still there seeps into our lakes and streams all year, diluting the salt recently flushed into the streams.
But once the groundwater reservoir becomes salty, we lose that natural flushing. Each spring thaw will dump salty water into streams already salty. Then, the whole destructive process will accelerate--with the lakes building salt levels faster.
Or, if the city eventually does start to cut back on salt, their good efforts will have less and less effect, due to salt seeping out of the ground.
Over two thousand years ago, Rome finally conquered the rival city of Carthage. To make sure Carthage would never rise again, Rome salted the ground of Carthage, to destroy their economic base. Isn't it strange... we seem to be doing the same thing to ourselves--ever so slowly. Tick, tick....
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More about salt overuse in Madison here.
The photo at top was one of many carp found dead at Odana ponds, on 4/1/11. Biologists said it was likely due to oxygen deficiency. But... it turns out that high salt levels make oxygen depletion more likely. And, very high levels of salt were measured in the pond about this time. This is a good eaxample of how we have to take action, even when the science isn't very clear.