I was confused. The falls upstream gush with water all year...
... but the water under the bridge is usually deep and slow-moving, because of the dam just downstream.
I wondered if dry conditions had exposed some of the rocks in the channel, but it had rained recently, and the river was running a bit higher than it had been previously. I glanced across the street and noticed a crane on the dam.
The water behind the dam was about 8 feet below its normal level, probably due to the construction or maintenance occurring on the dam. The lowered water level allowed a glimpse of the riverbed that is usually flooded behind the dam.
In addition to the exposed bedrock, there was a smaller concrete structure that I'd never seen before.
I'd assumed that the mill dam was built on a steep falls, just like the Middlebury waterfall, but in fact, the dam holds back water that would otherwise cascade over a series of rapids.
The area just below the dam is called 'salmon hole', and for good reason - Lake Champlain and the Winooski River support a population of landlocked salmon.
Above: "Salmon Hole" during April snowmelt from April 2011, after a winter of record snowfall in Vermont.
Before the dam was built, the salmon must have been able to work their way up the rapids. Now that the dam exists, the salmon are blocked in their path to spawn, but there is a cooperative effort to move the salmon beyond the dam and another dam just upstream. The dam also produces clean hydroelectricity - and unlike other larger dams, it doesn't flood a large area.
It does flood the Winooski
I'm not sure how long the construction will be going on, but if you're in the area, you might as well wander down to the bridge and check it out. Even if the construction has ended, it's a good excuse to go visit the river.
Click here for some historic photos of this dam and other dams on the Winooski.