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CharlesFrozenDriving down Needham St a few days ago I noticed a curious and (so far) inexplicable phenomenon.

If you stand on the Needham St bridge over the Charles River and look upstream you’ll see that the river is frozen.  That’s not a big surprise given the recent chilling weather.

If you look downstream from the opposite side of the bridge you’ll see that the entire river is water, not ice.

So the mystery is what’s causing this sudden thermal transition in the river, right at the Needham St bridge.

CharlesMeltedThere’s one possible clue that I could see.   Right beside the bridge a small non-frozen tributary comes out of a culvert under Oak St and joins the main river.  I’m pretty certain, this tributary is South Meadow Brook.  That small brook goes past Countryside School about a mile way, crosses Needham St about half way down and then appears/disappears below ground a few times before joining the Charles River at the Needham St bridge.

If this little brook is what’s melting the Charles at the bridge it would have to be very warm water, especially because there’s not much volume of water in the brook.    There’s no reason you’d expect this little brook to not be frozen.  I didn’t check to see if the brook is frozen further upstream.

CharlesTributarySo all you amateur hydro-thermologists, here are my questions.

1. Is the brook melting the river

2. If so, what’s heating the brook water

3. If not, what’s melting the river water

If anybody happens to be on Needham St today, take a look at where the brook crosses under Needham St (by the RR tracks and Jiffy Lube) and let us know if it’s frozen up there.