text from wordpess link in post #3:
"Where the pool stops"
"There is one stream in the Delaware Water Gap National Rec Area that is the coldest in the park. Conashaugh Creek at the northern side of the PA side. It comes steep through several deep ravines and when it hits the flat piece of topography about a kilometer above the Delaware River it dips underground for a few hundred meters before coming puddling back out for the last downhill bit. It’s off a side road (that is now closed from flood damage) and as far as I can tell no one really goes back there except for a few horses (and their people). All of these reasons make Conashaugh The-Greatest-Stream-In-The-Park.
For being largely spring fed and with all that underground flow, Conashaugh generally stays in a range of 7-12C. This year, a hot droughty year, it made it all the way to 15C in one section. Most streams in the park are topping 18-21C, which is a big difference when you’re a brook trout (who must migrate out of a stream, find a deep cold pool, or die around 23C). Going underground makes a huge difference.
(image here)
That pool is about 1.5km from where it meets the Delaware, is about 8ft deep, frigid in the middle of summer, and doesn’t resurface for another 500m+.
The pool in the picture above amazes me. It’s deep, cold, and there is a significant amount of water flowing into it. But there is no outflow. It just stops. Right there. The start of an underground stream. Geology is kind of amazing like that: the water doesn’t just diffuse everywhere underground (like I think it should), it still moves along like a stream, flowing in the same way that it does above ground.
It used to be that Conashaugh was the only stream that did that. This year, however, several other streams have joined Conashaugh in going underground for a short way. Although these new underground streams are less by natural ability and more as the result of (you guessed it) last fall’s flood.
For example, let’s take a look at Dingmans Creek:
(images)
Where’s the stream? Or rather, where’s the hillside that used to be there?
Mary is standing where a 15ft wide stream used to be. There also used to be a tree-ed hillside behind her. Well, we can see where the trees went. Here’s a pulled back view:
Well… it sure is flat.
And so, Dingmans Creek now has its own groundwater (sort of). Mostly because the ground covered over it. I can assure you, though, that it does come out the other side again. We didn’t measure the temp on the downstream side, but it sure felt quite a bit cooler. And therein lies the tricky part about working in ecology, or just about any of the sciences where you actually work with nature outside: everything is a trade-off. Yes, the hillside collapsed and caused some massive erosion and damage, but there is now a lot of large woody debris (trees and limbs and whatnot) in the stream which are excellent for habitat, in-stream nutrients, and food resources. Yes, the stream is now buried and fragmented, and to anyone walking by it looks entirely dead, but the water is just underground where it can get cool again, which is better for the fish (or at least the fish I’m studying).
A similar thing happens in a stream further south called Spackmans.
(image)
Quite the pool, and the debris jam.
Hill collapse. Tree jam. Buried and gone for just under 50m before coming out the other side. Just at the end of the pool."
