Why the Charles doesn't seem to flood as much as other rivers

Natural flood control in action this afternoon along the Charles River near Milliennium Park in West Roxbury.

Part of the reason you're not hearing much about flooding along the Charles is simply because a lot more rain fell up near the Merrimack than around the Charles. But part of it might also have to do with a decision made by the Army Corps of Engineers in the 1970s.

Water levels on the Charles at Mother Brook in DedhamUntil the '70s, the federal and state governments used classic engineering techniques to try to reduce flooding in the Charles - they built a dam at the mouth and some mega-pumps to pump water from the river into the harbor. And the Corps came up with a $100-million proposal to build levees and flood-control dams along the middle Charles. But the Corps abandoned that plan in favor of something more unusual: It began buying up or acquiring easements to some 8,100 acres of low-lying riverbank land from the Medfield/Millis line to the Dedham/Boston line - and then just let the land sit there.

The idea was that the various parcels of land would act as giant natural sponges during floods, absorbing vast amounts of water quickly, then releasing it slowly as the river receded. And it seems to work. During heavy rain (or the spring thaw), the Medfield/Millis border becomes a large lake - but since nobody lives on the Corps land, nobody has to be evacuated, either. You can see similar flood control in action from the top of Millennium Park in West Roxbury - or even across from the northbound side of Rte. 128 just past Great Plain Avenue.

Acquiring the land cost $10 million - or 10% of what the government had originally expected to spend on manmade structures.

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    Comments

    That confirmed my suspicions

    The Charles meanders past the end of my dead end street near the boathouse in Auburndale and I have often wondered other than the Watertown Dam and the locks near the Science Museum what was keeping the water form overflowing the banks. Yesterday I took a ride down to see if the park at the MDC property had flooded yet, but the water is barely over the normal bank level.
    At the 'duck feeding area' it is to the edge of the parking lot, but it hasn't breeched the border yet.

    At the Mother Brook

    By on

    There's a small dam that controls how much water leaves the Charles to head toward the Neponset (I'm easily amazed, but it's still something that normally, one-quarter of the Charles's flow is diverted to the Neponset). Yesterday, the water was high enough that you almost couldn't tell the dam was there.

    Science Museum is no longer an active dam

    The 'Old' Charles River Dam, which the Museum of Science sits upon, no longer operates. It has been replaced by the 'New' Charles River Dam, just east of the Zakim Bridge. You can walk across the 'New' Dam.

    nature's a beautiful thing.

    By on

    Genius. And glad of it. I wish there were similar plans done on the merrimack.

    or in peabody! hey! let's build an entire city on top of creeks. we'll just build culverts and tubes to divert the water while it's underground!

    pfth.

    Mother Brook is a huge

    By on

    Mother Brook is a huge reason why this works. The flood surge in the Neponset Basin flows through to the Harbor relatively quickly. By the time the diverted surge flow from the Charles hits the Neponset the Neponset's surge has passed. If this wasn't the case - the lower Neponset would flood quite frequently. There really isn't any "plan" for the amount that should, could, would be discharged into the Neponset The quantity of water that is diverted was settled many, many years ago and is not really regulated.

    The control on the Mother Brook spillway is actually not fully fuctional. It slowly falls (allowing more water in) and every few days someone goes out and cranks it back up. Check out the gauge: http://waterdata.usgs.gov/...&site_no=01104000<?a>

    You can see this pattern quite clearly.