When Frederick Law Olmsted designed Brockton’s largest park in the 1930s, his centerpiece was a chain of small lakes and ponds.
One of those, Ellis Brett Pond, was for years a popular swimming hole. Photographs from the 1950s show hundreds of people, adults and children alike, lining a sandy beach on summer days and playing in knee-deep water.
The pond’s glory days as a community gathering spot are long past. What remains is a shallow lake wrapped around woods and wetlands. But in big storms, it can fill up quickly, and that’s what concerns officials in the city of 95,000.
The dam holding back Ellis Brett Pond is nearly a century old, and Brockton officials worry about its ability to hold up in the years ahead.
The pond’s spillway has been determined to be inadequate for a historic storm. City officials also want to widen the back of the dam to meet state regulations and install an automatic gate that would allow city workers to steadily release water from the pond remotely to ensure the spillway does not get overloaded.
Without these upgrades, there is a risk the dam will fail and inundate hundreds of homes and businesses downstream. In the water’s path would be a public housing development, city offices and a church.
“The trend is toward more significant weather events and, for public safety, having a dam that is able to meet the possibility of larger events makes 100% sense,” Parks Superintendent Tim Carpenter said.
He estimates the desired repairs would cost about $2 million, money the city has not secured.
The dam was among those highlighted in a two-year investigation by The Associated Press. The AP identified at least 1,680 dams nationwide that are rated as high-hazard because of the potential for loss of life if they failed and are considered to be in poor or unsatisfactory condition.
Emergency plans obtained by the AP indicate that thousands of people living and working downstream could be at risk if those dams were to catastrophically fail, while separate inspection reports cite a variety of problems. Those include leaks that can indicate a dam is failing internally, unrepaired erosion, holes from burrowing animals and extensive tree growth, which can destabilize earthen dams. In some cases, inspectors also flagged spillways that are too small to handle the amount of water that could result from increasingly intense rainstorms due to a changing climate.
The AP’s investigation covers the U.S. territory of Puerto Rico but excludes five states that did not fully comply with records requests.
In Massachusetts, the AP found 39 high hazard dams that are in poor or unsatisfactory condition. Fourteen of those were on a list of 100 that a 2011 state audit determined were in poor and unsafe condition.
The number identified by the AP could have changed over the last year, if any of the potentially problematic dams were recently repaired.
Many of the deteriorating dams are decades old, and in some cases date back more than a century. Most were built to provide water and power to textile mills and other manufacturing sites. Today, most structures that hold back ponds and lakes are for recreation, flood control and drinking water.
A review of dam inspection reports in Massachusetts found similar problems to those plaguing structures nationwide.
Many of the poorly maintained dams are in densely populated areas, meaning a failure would inundate entire neighborhoods, shopping districts, highways and rail lines.
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