This dam problem needs to be fixed, cities say

By Jon Chesto Globe Staff/ November 17, 2018/ Original Article

Waiting for the Big One: Those dramatic floods in downtown and the Seaport last winter didn’t only serve as a wake-up call to business and civic leaders within the city of Boston.

It also added a new sense of urgency in neighboring cities, even ones without oceanfront properties -- communities such as Cambridge, Somerville, and Medford. That’s why these and other Mystic River watershed cities just started lobbying the Baker administration for $5 million to help improve the Amelia Earhart Dam's pumping capacity.

This is the Mystic communities’ biggest immediate priority in terms of resiliency: installing an additional pump at the dam. The 1960s-era barrierseparates the saltwater, tidal Mystic from the freshwater portion. Its three pumps have largely proven sufficient, so far, in clearing water out of the basin above the dam during times of intense rainfall.

But what happens if one pump breaks down? Or what about a storm that arrives with such ferocity that the three pumps can’t keep up? The dam’s designers anticipated this moment, by including room for an additional pump. A fourth pump could also help expeditiously remove saltwater if the dam gets breached by a storm surge from its harbor side.

This kind of equipment doesn’t come for free: A fourth pump could cost $15 million to $20 million, according to a Nov. 9 letter sent by the Mystic River Watershed Association to Governor Charlie Baker on behalf of 21 cities and towns. The $5 million request would cover the engineering costs and about one third of the actual project.

State lawmakers earmarked this money in a $2.4 billion environmental bond bill earlier this year. But it’s really the Baker administration’s call on how to spend it. And, so far, the administration has been noncommittal.

A spokesman for the Department of Conservation and Recreation, the state agency that operates the dam, declined to put someone on the phone who could talk about the issue. The spokesman did say the dam plays an important role in protecting residents from severe storms. But he didn’t comment specifically on whether the $5 million would show up in Baker’s next capital investment plan in the spring

The dam has endured some tough storms over the years. However, it’s a linchpin for the entire river, and the main tributaries that feed it. Failure could bring catastrophic ripple effects. The nightmare scenario: a deluge that not only swamps low-lying areas -- think Assembly Row or Medford Square -- but also causes storm drains across the region to back up.

It’s why Partners HealthCare executives are throwing their clout behind the request. The dam is just a stone’s throw from their Assembly Row office tower that opened in 2016. A fourth pump, they say, would substantially improve the dam’s effectiveness in reducing the intensity and duration of upstream flooding and any subsequent impacts.

To the municipal leaders in the Mystic area, the request seems like short money compared to the bond bill’s overall size, a cheap insurance policy. It’s a matter of when, not if, the Big One is coming. They want to be ready.

Jon Chesto is a Globe reporter. Reach him at jon.chesto@globe.com and follow him on Twitter @jonchesto.