A stretch of the Piscataquog River near the Goffstown-New Boston line that generated a huge ice dam a year ago is at it once again, to the point that the U.S. Geological Survey has installed a special river gauge to warn of flooding.
The rapid deployment gauge was placed on the South Branch Piscataquog River on Thursday, Feb. 14, to monitor water levels and potential flooding from a mile-long ice jam that extends into the towns of New Boston and Goffstown.
The gauge will transmit data by satellite every 15 minutes to provide information to the public as well as local and emergency managers. It will be active until concerns associated with the jam have subsided.
The ice jam extends from the Howe Bridge Road crossing in New Boston downstream to the Goffstown-New Boston town line. It formed after a deep freeze in late January that resulted in a thick layer of ice on the river’s surface. That ice was broken up with subsequent warmer temperatures and heavy rainfall, and a resulting increase in streamflow transported the ice downstream until it became jammed.
This type of event is called a “breakup jam.” They are highly unstable and can release ice and water suddenly, flooding nearby homes, businesses and roadways, and the ice blocks could be damaging to trees and nearby structures.
The river passes through the center of town and along Route 13 near the Goffstown-New Boston town lines.
Similar jams and ice breakups have occurred in this area before. The USGS has been monitoring the river since 1941, with a noteworthy ice jam occurring just one year ago Jan. 13, 2018.
The USGS, in cooperation with the New Hampshire Department of Environmental Services, operates a permanent streamgage just upstream from this ice jam, and that will be used to provide additional insight on river conditions.
The USGS began monitoring streams in New Hampshire in 1903 and currently operates 53 permanent streamgages in the state.