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Tiny Windham Brook Is A Roadblock In I-93 Widening Project

The widening of I-93 is without doubt a massive public works project. It’s also been a massive political issue. But its full build-out may end up being blocked by a tiny brook.

Driving south on I-93 in Windham, you won’t miss the fifty-foot wall of granite dwarfing the backhoes that chip away at it.

But what you won’t see from the road is a small stream known as Dinsmore Brook. Concerns over its water quality have been threatening to reduce the width of the road from four lanes to three.

“It seems like it’s the biggest kept non-secret that is going on in New Hampshire right now.”

Al Letizio is a Windham selectman and no fan of what he terms a ‘perception of a brook.’

And it’s true that Dinsmore isn’t much to look at. It crawls around and beneath the exit three area mostly through culverts and man-made ditches before spilling into nearby Cobbetts Pond. It contains little life but lots of chlorides.


Dinsmore is one of four streams between Derry and Salem with chronically high levels of chloride, mainly from road salt. And it’s become the hardest to clean up.

Tom Irwin with the Conservation Law Foundation says too much chloride in the watershed can be dangerous.

“Too much chloride pollution in our rivers and streams is having an adverse impact on fish and aquatic life.”

Which might be true in other water bodies across the state, but the DES confirms Dinsmore Brook is home to no aquatic life. And since it’s expected to be 70% artificial by next year, no one’s expecting life to bloom there any time soon.

The regulation that DES and EPA are working with is absolute, and it’s been a struggle for the state to meet it.

“This is a really, really big project,” says Ted Diers with DES, “and if you’ve been out there to visit, and anyone who’s driven through that area knows that this is a monumental task.”

DES came up with benchmarks that needed to be met before the state could move ahead with the fourth lane. They stipulated the amount of salt that de-icing trucks were allowed to use and how clean the water bodies needed to get (whichever comes first).

“We have this whole series of things that we have to track relative to flow and winter severity and amount of salt being put down and then run that against the actual monitoring data that we get in order to try to generate a picture of where we’re at.”

Diers says the other three brooks near ninety-three that had similar problems are now on track to meet requirements, but not Dinsmore.

The bottom line is that the DOT’s required to either cut its salt use in half by exit three or meet strict water quality standards.

Highway Project Manager Pete Stamnas is overseeing the widening of I-93. He says the state is making progress.

“What we’ve seen is about a 25% reduction of the salt that’s used in this watershed.”

Stamnas says salt trucks have been refitted to spread brine instead of rock salt and temperature sensors on the roads help them use the salt more efficiently. Each refit costs about $4,000, but they’ve been saving about $30,000 a year on salt. So they’re not only improving the water quality by salting less, they’re saving taxpayers money.

But it’s an open question whether the state will be able to lower its salt use by another 25 percent or if Dinsmore Brook will see any improvement in water quality.

In the meantime, the slow work of widening the highway continues. When it’s all said and done, it’s expected to cost more than three quarters of a billion dollars.

Folks like Al Letizio of Windham worry that a project that ends with anything less than four lanes would be a failure. 

“After all the expenditure of this money, and all of the time—the fourteen years—and all the waiting, the end point will not really do too much to change anything.”

The DOT hopes to complete construction around exit three in two years. Construction of the northern part of the corridor up to Manchester is slated to start next Spring.

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