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Newburyport faces costly challenges as sea levels rise, river flooding increases

Newburyport faces costly challenges as sea levels rise, river flooding increases

Newburyport has been taking some farseeing steps to prepare itself for storm surges, sea level rise and inundations from Merrimack River floods. But city officials are concerned that two major pieces of infrastructure — the city’s water reservoir and its sewer treatment plant — may be subject to flooding in the short term, and actions need to be taken to safeguard them.

For the sewer treatment plant, the longterm may prove even more challenging — it will likely have to be moved to a new location at the opposite side of the city.

Newburyport-based Storm Surge, a local non-profit dedicated to educating the public on issues related to coastal flooding and sea level rise, sponsored a well-attended forum last week where city officials spelled out their efforts to prepare for storms and rising water levels. The city has conducted extensive studies of its most vulnerable areas, and is in the process of developing a brick-and-mortar action plan to begin the process of protecting areas that are (and will be) subject to flooding.

The MWRC attended the forum and found two Merrimack River-related issues to be worthy of added public attention.

Artichoke Dam

This image shows the location of the Artichoke Reservoir (outlined in blue). The dam can be clearly seen from Route 113 at the Newburyport-West Newbury line.

City Engineer Jon-Eric White noted that the city’s water supply is vulnerable to contamination in extreme conditions. The city’s water comes primarily from the Artichoke Reservoir, a large manmade body of water on the border between Newburyport and West Newbury. The reservoir was created by damming up the Artichoke near its entry-point on the Merrimack River.

But White noted the dam is fairly low, as can be seen in the photo at the top of this article. Only a few feet separate the clean reservoir water from the Merrimack. The Merrimack is brackish at this location, and is subject to raw sewage contamination from sewage treatment plants upstream in Haverhill, North Andover, Lowell, Nashua, N.H., and Manchester, N.H.

The dam nearly breached during the infamous Mother’s Day flood of 2006, a massive rain event that caused flooding all along the lower Merrimack. That flood may be a precursor of what’s to come. According to the EPA’s data, flooding along the Merrimack is growing in intensity as global warming produces more substantial rainfall events, and development along the river causes more storm-related runoff to flow into the Merrimack.

White said that raising the dam is a priority for the city, and he hopes to begin work within the next year.

If the reservoir dam is breached, Newburyport does have auxiliary sources of water for short term use. It has two wells and two water towers, but neither is intended to replace the reservoir.

Wastewater Treatment Plant

Newburyport recently completed a $35 million+ upgrade of its wastewater treatment plant, located along the bank of the Merrimack River about a half mile east of the downtown. But the plant’s longterm viability is in doubt, said White, due to rising sea levels.

The level of the Merrimack in Newburyport is expected to rise as the ocean rises, and that places the plant in the path of storm surge flooding. Although the city took efforts to raise the level of the plant during the upgrade, some sections of it remain low, said White. In the short term, the city will need to consider fixes to low-lying doorways and access points that storm water could surge through.

Newburyport’s wastewater treatment plant is outlined in blue. In the next 30-40 years, the location of the plant will likely have to be moved.

In the long run — 30 or 40 years — Newburyport will likely have to move the location of its sewage treatment plant. A location along the Merrimack is probably not feasible. White suggested that the city may need to build a new treatment plant on the opposite side of town, near the Little River and the Newbury town line. The Little River wouldn’t be able to handle the flow of treated wastewater that the plant generates, so that wastewater would have to be pumped back to the (current) plant’s wastewater outflow pipe, which dumps treated water into the fast-flowing Merrimack River.

For those familiar with Newburyport’s topography, this represents a substantial bit of engineering. The core of the city is a fairly narrow strip of land, with a high spine (known as The Ridge) that runs through its center. On one side of the spine the city drops down to the Merrimack, and on the other down to the Little River. The city’s wastewater system is designed to flow down toward the Merrimack, so a new plant would require that wastewater to be pumped back up over the high ground of Newburyport, then down to the new treatment plant. Then it would need to be pumped back up over Newburyport’s spine and out into the Merrimack.

That’s a headache for a future generation, but it’s not so far away.