Tidal Brandywine

[geebee]

i walk the river below West st dam every day at lunch pretty much year round, and the last couple of days every hole over 3ft deep and out of the main current has been rammed with fish.

yellow perch, small carp, panfish, small bass, juvi stripers, and small pods of shad are all over the place and there are some large carp feeding agressively in the water at the dam.

it must of been a mild winter and relatively flood free spring, because the 'bait' is way up on the last two springs.

with the dam now top sliced and an easier path upstream for them, it could be a banner year on the B upstream for bass.

cheers

Mark.

 

[Fredrick]

I don't live to far from there if you want to meet up say the word

 

[troutbert]

geebee wrote:

with the dam now top sliced

Could you explain what this means? Does it refer to some sort of partial dismantling of the dam?

Are there any articles or photos available on line about this?

 

[geebee]

Hey troutbert, yes - last spring a big flood took off a 150ft 2-3ft section of blocks off the top of the dam.

hence, it was 'top sliced" - the Brandywine Conservacny had been lobbying for removal of the dam but the top slice has provided the shad easier access and the blocks have provided some nice structure just below for fish to hold in.

i've seen carp over 20lb and BIG muskies holding in the new dam pool.

Fredrick - i only work in wilmington so i've never fished it down there. I live up in Landenberg, so i fish it more up around shaws bridge or up on the EB at Dowlin Forge rd.

cheers

Mark.

 

[GRP]

I'm probably going to hit this up on Sunday. I'll post results.

 

[sarce]

Mark I think you're right about it being relatively flood free this past winter and spring. A quick check of one of the gages should confirm that. Never been that far downstream myself, wasn't aware there are muskies around. Sometimes they get out of Marsh Creek but I was always told they get shocked out and relocated to the lake because the trout fishermen fear they will eat all the stockies.

 

[troutbert]

geebee wrote:
Hey troutbert, yes - last spring a big flood took off a 150ft 2-3ft section of blocks off the top of the dam.

hence, it was 'top sliced" - the Brandywine Conservacny had been lobbying for removal of the dam but the top slice has provided the shad easier access and the blocks have provided some nice structure just below for fish to hold in.

Sounds good. I think in many cases a partial removal or partial breaching of dams, enough to allow easy fish passage, would be preferable to full removal.

Because leaving some structure there can provide structural diversity, which is often lacking in our streams since they have been so highly altered.

 

[geebee]

troutbert wrote:
Sounds good. I think in many cases a partial removal or partial breaching of dams, enough to allow easy fish passage, would be preferable to full removal.

Because leaving some structure there can provide structural diversity, which is often lacking in our streams since they have been so highly altered.

absolutely, a Vee breach often is better for the fish - especially in low flows as it provides concentrated oxygenation and back eddies.

had they taken the dam out, it would have just been pocket water up to the next dam.

 

[troutbert]

What is a Vee breach?

And have you ever seen one done here in the US? Or any other type of deliberate partial dismantling or partial breaching of a dam?

The dam removal movement has been going for some years now and everyone I'm familiar with here in PA has been a full removal, never a partial dismantling, partial breaching type of thing.

In one of these cases I asked about the possibility of doing that and was told the PA DEP will not allow that, that they require that a dam be fully removed, along with all debris.

 

[ebroesicke]

Troutbert:

The DEP does require (as I've been told) full removal. I do think that in some heavily silted situations they 'notch' the dam and increase the size of the breach over time to allow the sediment to disperse gradually.

 

[geebee]

troutbert wrote:
What is a Vee breach?

And have you ever seen one done here in the US? Or any other type of deliberate partial dismantling or partial breaching of a dam?

yuh, out in the Berkshires of western MA - typically on smaller creeks. they notch it in one, two or three spots.

i've also seen what they call 'crib' dams where the concrete top is taken off, leaving just a wooden frame or 'crib' at or below the water line - creating a riffle downstream .

its also pretty common in other States - CT & MA, where the resulting dam removal would lead to a wide slow flat, to leave behind the dam 'wings' to concentrate the current. this is normally accompanied by log vanes on each bank downstream to keep teh flows going and provide cover.

I am going to take a wild guess and say the DEP requires total removal, to remove any chance of a partial collapse and minimize their potential liability.

imho its not always necessary. it depends on the stream gradient.

and correct me if i'm wrong but i think the White Clay in DE has a partial dam removal just over the State Line doesn't it ? where the mill used to be ?.... though that looks like it may have been done while it was still DuPont land.

cheers

Mark.