Do not eat locally caught freshwater fish

The Merrimack River, seen on Aug. 15, 2023. (Peter Currier/Lowell Sun)

LOWELL — The Massachusetts Department of Public Health has warned freshwater anglers and fish eaters against eating most fish caught in local rivers and ponds.

In a recent advisory, the DPH cited contamination with hazardous chemical compounds and a naturally occurring metal as reasons to avoid or minimize consumption of locally caught freshwater fish.

PFAS, or perfluoroalkyl and polyfluoroalkyl substances, also known as permanent chemicals, and mercury are the main substances of concern in the region’s waterways. The most recent advisory from DPH is based on sampling and testing of rivers and lakes across the state. The advisory is specific to where the fish are caught.

Dracut Public Health Director Dave Ouellette summarized the general recommendation as “no more than one meal per month of freshwater fish,” and in some cases, no more than once every two months. The DPH also advised against eating largemouth bass.

Vulnerable people — children under 12 and anyone who is pregnant, breastfeeding or could become pregnant — should avoid freshwater fish altogether.

The DPH excludes trout from the advisory because they stock state water bodies twice a year.

The Concord, Merrimack and Nashua rivers, as well as the Lowell Canals, top the list of waterways with contaminated fish. Many local lakes and ponds are also on the list.

The Concord River advisory affects Concord, Carlisle, Bedford, Billerica and Lowell.

The Merrimack River advisory affects Tyngsboro, Chelmsford, Lowell, Dracut, Tewksbury, Methuen, Andover and Lawrence.

On the Nashua River, the advisory affects Clinton, Lancaster, Harvard, Shirley, Devens, Ayer, Groton, Pepperell and Dunstable.

Lakes and ponds are also affected by the notice. These include, but are not limited to: Nabnasset Pond in Westford; Ames Pond in Tewksbury; Heart Pond in Chelmsford and Westford; Massapoag Pond in Dunstable, Groton and Tyngsboro; Mirror Lake in Devens and Harvard; Flint Pond in Tyngsboro; Forge Pond in Littleton and Westford; Long Pond and Mascuppic Lake in Dracut and Tyngsboro; Hickory Hills Lake in Lunenburg; and Falls Brook Reservoir in Leominster.

To read the full list of water sources contaminated with PFAS or mercury, visit mass.gov/lists/fish-consumption-advisories.

The DPH leaves responsibility for E. coli testing to cities and towns.