Going with the flow at Cedar Lake

By Abigail Franklin and Chloe Wardropper

Chloe Wardropper prepares to measure stream velocity at Cedar Lake.

On rainy days, Abigail Franklin, the anadromous fish expert for the Cape Cod Water Resources Restoration Project, and Chloe Wardropper, a USDA Natural Resources Conservation Service intern, rush to North Falmouth to take advantage of raised water levels in the small stream connecting Cedar Lake with Rand’s Canal.

They’ve been tracking the stream’s flow since February 2011, taking measurements that will inform the design of a replacement fish ladder and culvert. The project will improve passage from Rand’s Canal, near Megansett Harbor, into Cedar Lake, one of the herring runs on the Buzzards Bay side of Falmouth. 

Stream flow, or discharge, is calculated by multiplying water velocity by the area through which it flows.  United States Geological Survey gauges at the Herring River in Harwich and the Quashnet River in Falmouth provide data on nearby watersheds, but since those rivers are much larger, it is difficult to directly compare them to this small stream.

The measurements collected at Cedar Lake will provide an important baseline for the fish ladder project and establish a flow monitoring protocol that can be used for other planned Cape Cod fish passage projects. 

Measurements are taken by dividing the stream into six intervals at right angles to the flow.  Using a Pygmy current meter (a spinning device that is pushed by the water) and wading rod, Abigail and Chloe determine velocity and depth for each segment, and then add them together to get the total flow. 

Since February, stream depths have ranged from 4 to 15 centimeters and discharge has varied, generally following depth, from .012 to .051 cubic meters per second. 

The shallow depth results in slightly aching backs at the end of the day, but the scenery is beautiful, and they never know what might float down the stream: Abigail’s feet recently encountered an unsuspecting muskrat!