Fad or fact - legacy sediment stream cleanup?

[salmonoid]

I drove past this project last Sunday before I knew what was going on, and wandered what the heck WAS going on. I knew route 222 has been horrible for construction this year - bridge work, paving, and the construction of a church right beside this stream, but I couldn't imagine how in the world anyone could get away with such massive upheaval of a flood plain. Then, I found out its some sort of pilot stream restoration. What do you think - will the stream end up in a few years in the same place it started before the project? Will nutrients in the sediment removed still leach when whoever buys the topsoil moves the problem to their back yard?


Here is the article about the legacy sediment stream cleanup.

 

[salmonoid]

Snapped some pictures mid-week, when I was sitting in traffic, waiting for the light to change (composite photo). The mound of dirt to the right is what was removed from the flood-plain, and the stream itself meanders back and forth. Sorry about the darkness of the photo - cell phones take pretty good photos these days, but I've noticed mine doesn't do so good in odd light situations.

 

[troutbert]

It makes some theoretical sense. But the project cost 1 million dollars, and that's on a small stream. To do this on a large enough scale to make a difference to the Chesapeake Bay is cost prohibitive.

A more practical solution is to leave the old mill dams in place as grade control structures, draw down the ponds where they are creating thermal pollution on coldwater streams, but leave the dams in place to keep the sediment in place. And spend your money on creating wide, permanent, naturally vegetated riparian buffers.

 

[crs5942]

This is actually a very good place to do research on the impacts of removing legacy sediment. The USGS has been collecting data in this watershed for several decades now.

 

[Chaz]

I'm taking the middle of the road here, I think in some cases that dam removal and removal of legacy sediments will work, but I like to see it work along a long section of stream. Meaning a couple of miles. Plus it is very costly, unless you're getting big bucks for the sale of topsoil.
I think the most practical use of scarce conservation dollars is to breach the dam and leave the bulk of it there to keep the sediments in place then planting the flood plain.

 

[TimMurphy]

Dear Chaz,

I'm sort of with you on this. I understand the theoretical implications of the process but the practical end is sorely lacking. I mean, if you move it upstream won't it all return eventually? If you downstream or out of the drainage doesn't it then just become someone else's problem?

It's the same thought process that is people in NE PA and the Southern Tier of NY are exhibiting in response to the floods of early September. Many people are claiming that dredging the Susquehanna will alleviate the flooding problem.

It's a temporary solution at best, the river will always find a way to be 3 feet deep across 95% of the drainage, finding the course of least resistance is what water does best.

Once you remove 1,000,000 cubic yards of topsoil what the heck do you do with it? The Earth is not a static item. Things do change, and man can and does accelerate or slow the process depending on his actions, but make no mistake, the change will always occur.

Regards,

Tim Murphy

 

[TimRobinsin]

I think there are many places for topsoil around Lancaster. Just look at one of the hundreds of fields which are below the road because of the topsoil being slowly removed. I refer specifically to the the sod farms here in my area of Lancaster which remove quite a bit of topsoil each year and ship it else where. They could easily use this topsoil.

 

[TimMurphy]

Dear Tim,

That's kind of my point, there is nothing you can do short of paving over or concreting over the topsoil to keep it physically in place.

Neither one of those are good options but they have been the most common option. Doing either intensifies and accelerates the drainage of storm water which often increases the rate of topsoil removal. It's a sort of never ending cycle.

Regards,

Tim Murphy