The extremes of weather the region has experienced in recent years have posed challenges to keeping area waterways clean, but local watershed associations said infrastructure improvements could help keep rivers clean in the future.
The Environmental Protection Agency released reports earlier in the summer detailing the quality of the water in individual waterways using data from 2022, and the specific pollution and invasive species challenges faced by each. Four local rivers — the North Nashua, Merrimack, Shawsheen and Concord rivers — received relatively poor grades in multiple categories, and in most cases, the expectation is the trend will have continued into this year, but for a different reason.
Jessica Veysey Powell, a watershed scientist with the Nashua River Watershed Association, said the Nashua River overall has been in pretty good shape, but that the North Nashua River running through Fitchburg has faced its share of problems.
“When we get storm events, not even just big storm events, raw sewage often flows into the river,” said Powell.
What Powell described is a combined sewer overflow, an event in which a sewage system is unable to handle a rise in the volume of water, typically through rain, and overflows into nearby bodies of water, contaminating them. In 2023 there has been an abundance of CSO events due to the high rainfall totals the region has seen this year.
The data from the EPA, however, covers 2022, when the region was in the exact opposite situation: a severe drought.
“The drought last year didn’t help things,” said Powell.
Along with the issue of just not having enough water, droughts also pose an issue by turning bodies of water into perfect breeding grounds for certain bacteria, like E. coli, which found its way into many local rivers in 2022. There is also the perpetual issue of impervious surface runoff, Powell said, where rain falling on pavement carries pollutants from vehicles into nearby bodies of water or soil.
The EPA reports also noted the presence of lead and “chronic aquatic toxicity.”
“We are encouraging towns in our watersheds to implement green infrastructure along rivers and streams,” said Powell, adding that strategically using some vegetation can slow the flow of pollutants into bodies of water so that it is less concentrated.
The Merrimack River, which runs directly through Lowell, faced similar issues, and the EPA included in its report the presence of mercury in the tissues of fish found in the river last year, along with the presence of E. coli.
Merrimack River Watershed Council Policy and Education Specialist John Macone said that it isn’t typical for these reports from the EPA to change from year to year, and 2022 was apparently no exception.
“There is always mercury in the fish, and there is impairment for them to get up the river,” said Macone. “The fish ladders are not getting the job done.”
Macone said the Merrimack is one of the most important rivers on the East Coast for migratory fish like herring and shad, and that those fish end up being critical to the food supply of the ocean when they migrate there from the river.
“There are whales that have been seen eating these fish,” said Macone.
While the EPA data reflects a year of severe drought, Macone said the intense rain the region has faced this year will make the 2023 data look similar to 2022.
“This has been the highest number of CSO events I have ever seen,” said Macone. “That is a big issue for Lowell.”
The Concord River, which runs between Concord and Lowell, was also identified as having issues with E. coli in 2022, mostly due to warm, stagnant water conditions, but its main problems stemmed from invasive species. Those included the Asian clam, curly-leaf pondweed, Eurasian water milfoil, European water clover, fanwort and water chestnut.
Alison Field-Juma, executive director of OARS, said the Concord River, unlike the others, has not faced many problems with CSO events, as there is only one location on the river where they seem to happen near the part where the Concord reaches the Merrimack.
One issue faced by the Concord River that wasn’t reflected in the report, Field-Juma said, is the presence of chlorides, or salts, in the water.
“A lot of the higher chloride readings we get are along the (Interstate) 495 and Route 3 interchange and the Lowell Connector,” said Field-Juma. “This would point to highway salt as the likely source.”
Field-Juma said that along with the EPA’s data, OARS is preparing a five-year report of the Concord River themselves, of which they hope to have a version ready in the late spring of next year.
The Shawsheen River, specifically the leg that runs between Burlington and the Ballardvale Impoundment in Andover, saw a lighter report from the EPA, with curly-leaf pondweed listed as the only invasive species, but with E. coli being detected as well due to the low and stagnant water.
Shawsheen River Watershed Association President Brian Henderson said the drought naturally caused some measurements like E. coli to get worse, but that it also may have made some measurements better.
“The water was so low that it wasn’t moving much, which can increase problems with the measures. But there was also a lack of rain washing pollutants into the water, so some numbers were actually better,” said Henderson.
Henderson expressed the same concerns as Field-Juma in regard to chlorides, which he said are an issue in bodies of water statewide.
“The ice melt salt gets into the system. Those are giving us issues with the building up of chloride in the water,” said Henderson.
He said the Shawsheen River is better than it had been years ago, but that any body of water that goes through communities with a lot of housing and roads will face pollution from impervious surface runoff, and that these bodies of water absolutely deserve to be protected.
“We want people to be aware of the importance of keeping these water sources clean,” said Henderson. “Like in Billerica, the Concord River is their only source of water. If someone upstream dumped a bunch of chemicals into the river, the whole town is done.”
