Officials flagged two dams as being severely damaged by the flash flooding in Leominster on Monday.
According to the Mass Office of Dam Safety, the Barrett Park Pond Dam was last inspected on November 18, 202. Federal data shows it was in poor condition when it was inspected in 2017.
The Fall Brook Reservoir Dam was last inspected on November 20, 2020, and found to be in fair condition. It is a High Hazard potential dam owned by the City of Leominster.
The dams were shored up to prevent failure Tuesday, and people who lived in the risk area were temporarily evacuated from their homes as a precaution. But with climate change making flooding events more likely, our infrastructure may see further safety tests.
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Federal data paints a picture of how many dams in Massachusetts pose a significant danger to human life and what condition they were in when last inspected.
Data courtesy of the National Inventory of Dams
What's the difference between hazard potential and a condition assessment?
Hazard potential focuses on the potential risk to human life and economic/environmental impacts were a dam to fail. Condition focuses on the physical condition of a dam at the time of an assessment. A dam can have high hazard potential but be in good condition. A dam with high hazard potential in poor condition is of concern.
Based on data from the National Inventory of Dams, there are 1,328 total dams in Massachusetts – Worcester has the majority of the bridges in the state – just over 400.
Dams are inspected an average of about every five years in Massachusetts and their condition and safety are assessed.
Only 37% of the dams in Massachusetts were given a satisfactory or fair rating after their most recent inspection, according to federal data. There were 267, or 20%, in the state given a poor rating, meaning remedial action is necessary– 3% of dams, 35 across the state, were given an unsatisfactory rating – meaning the dam requires immediate or emergency action. Seven of those are considered high hazard dams, meaning if they fail – they pose a risk to human life.
In Worcester County, 20% of the dams are rated poor and 13, or 3%, of the county’s dams are in unsatisfactory condition. The county has 100 high hazard dams - the most in the state.
The National Inventory of Dams is maintained by the U.S. Army Corps of Engineers, which works with federal, state and local agencies to collect the information contained in the database.
