Sunday, October 2, 2011

Where the Runoff Goes: East Middlebury Edition

I've noticed some unusual runoff patterns in East Middlebury, VT.  Rather than flowing into drains, or behind houses, runoff water in East Middlebury runs west along the main roads for long distances, often puddling on sidewalks or in the road.  During Hurricane Irene, the water flowing down East Main and Ossie streets was not only fed by local runoff, but by the overflowing Middlebury River as well.  Hopefully that does not happen again, but even when the river is not on the road, small 'creeks' form in places when the rain is heavy.  When it gets below freezing, puddles on the sidewalk and street freeze, causing problems.

The soil in East Middlebury is old sand from a glacial delta as well as newer sand and cobble deposits from the river.  As such, it is very well drained - aside from the river and a few larger streams, you don't see surface runoff in areas of uncompacted soil, even during downpours (an exception is in early spring when the ground is frozen, of course).  Water running off of drainspouts soaks into the ground almost immediately, is filtered as it passes through the sand to an underlying clay layer, and makes it into the river long after the rain has stopped.  Rain gardens on drainspouts aren't really necessary here, but when it comes to water channeled down the road (there are no gutters so it runs right down the road and sidewalk), I can see a lot of value in diversion of this water into small rain gardens or swales.

In trying to figure out where the need is greatest, I went out during two rainy days and documented how the water flows through town.  Here's a Google map of what I found:

View East Middlebury Runoff in a larger map

All of the water flows roughly from east to west (from right to left).  Brown lines represent water running down pavement or sidewalk, the green line is a soft-bottomed ditch that does allow some water to soak in (but would work better if it were a bit wider), and the blue line is a small creek that drains the area north of town.  In a few places the water runs into drains, but mostly these are blocked.

The areas of water flowing down the road are quite substantial.  The 'stream' flowing down Ossie Road is almost a half mile long!  This water flows down the road, picking up pollutants, rushing towards the river, and possibly flooding basements, and at one point branching off and wandering down a driveway (not pictured), instead of being diverted to where it can soak in.  There is clearly the potential to do something better with this water.

I also took lots of pictures.  A map including these pictures is here (unfortunately I don't have an easy way to get them onto Google Earth).  Take a virtual tour!


  1. This is a really cool thing to do. I'd love to see such a map for San Francisco. (Of course I have a local interest; I'd like to see a comparison of water runoff from Twin Peaks - grassland -- vs Mount Sutro Forest.)

  2. It was really fun... and would be neat to do in a hilly place like SF. I'm sure the different types of plant cover do have different runoff patterns... but it would be hard to track, because you'd have to find little watersheds of the same sort. Well, it never hurts to walk around in the rain and see what water is doing