Wednesday, July 12, 2023

Indian Well's Great Gully

"Great Gully" location at Indian Well State Park

The vast, mostly man-made gully at Indian Well State Park has cut the park in half and is getting close to  the Paugussett Trail. After every major storm, torrents of sand rush down the hillside and are dumped on Indian Well Road.

Much of the sand likely washes into Lake Housatonic, filling in the reservoir that generates hydroelectricity.  With no efforts to stop it, the head of the gully advances up the hill a few feet every year towards the homes along Village Drive. 

It's not easy walking up the gully, but you can do it. Park at the hiker lot located just across the street from the main park entrance to the beach and boat launch facilities. This is where a white-blazed trail goes steeply up the hill towards the Paugussett Trail. Instead of going up the trail, follow the utility road off to the right (north), through an open area with giant piles of sand, until you reach the normally dry streambed. Just go up that, dodging fallen trees. 
Undermined trees fall into the gully

If you're a geology geek, you'll love this. There are glacial sediments deposited by temporary glacial lakes. There's lots of unstable sand and obvious bedding. 

The lower parts almost never have water in them. 

As you proceed up the gully, it gets larger and steeper. You probably can't get out of it by climbing up the sides at this point. 

Approaching the head of Great Gully.

The rock under foot is loose, so bring a walking stick and some good boots. 

Pass under some roots next to 'the island'
Nearing the top, there is an island of sorts on the left that will eventually collapse, but for now a large Black Birch is hanging on to dear life. Duck under some tree roots to reach the head of Great Gully. 

The head of the gully

The head of the gully is constantly changing as it chews its way up the hill. As of 2023, it's now wide enough to enter from below. For a few years, it was as narrow as a construction trench and 12 feet deep. Very unsafe to enter. But it's pretty wide this year. Sadly. 

Head of Great Gully
The gully is both interesting (for geology nerds) and tragic. The way to stop it from getting worse is to stabilize the head. That's where water falls over the edge and eats away at the bottom, undermining the layers above until they collapse. There are engineering ways to do this, but the state has taken no interest. 

While there was undoubtedly always a stream channel here, Giant Gully is man-made. The houses and roads up the hill off Village Drive were built back before stormwater measures were required. If the housing developments were built today, a stormwater detention pond would probably be required so that floodwaters from the roads, driveways, and rooftops don't immediately wash into the stream channel.  The steep slope and sandy soil are no match for the uncontrolled runoff from these hard, man-made surfaces, and there is no room up above for a retro detention pond. The only solution is to come in from below and stabilize the head of the gully. It will be easier to do it now than later when it gets near the houses on Village Drive. 

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