Fish caught in the city's drinking water supply are not fit for human consumption, according to a warning from the Massachusetts Department of Public Health.
Area lakes, ponds and waterways are contaminated by mercury, which is toxic to the human nervous system, according to a report released by watchdog agency Environment Massachusetts.
The state Health Department's warning for Haverhill bodies of water range in severity from limiting consumption of certain fish to prohibiting the consumption of any fish caught.
Chadwick Pond, Lake Pentucket and Kenoza Lake, which supplies the city's drinking water, received the strongest warning: P6 — "The general public should not consume any fish from this water body."
Crystal Lake received three lesser warnings. P1, which says children younger than 12, pregnant women, women of child bearing age and nursing women should avoid eating fish from this body of water; P2, meaning the general public should avoid eating largemouth bass; and P4, meaning the public should limit their consumption of nonaffected fish to two meals per month.
The Millvale Reservoir received P1 and P2 warnings, while Lake Saltonstall, or Plug Pond, received P1, P2 and P3, which says that the general public should limit consumption of largemouth bass to two meals per month.
The greatest amount of mercury emissions comes from coal-fired power plants, Environment Massachusetts' report said. The toxin builds up in the fatty tissue of the fish. The water is safe to drink.
"Powering our nation's homes should not poison Massachusetts' waterways," said Audrey Richardson, clean energy associate for Environment Massachusetts. "Mercury pollution from power plans puts our environment and public health at risk, and we need the Environmental Protection Agency to force these facilities to clean up."
The Merrimack River carries warnings against eating any fish for children and women who are pregnant, nursing or of childbearing age. The public should eat no more than two meals per month of largemouth bass caught in the river. The Merrimack also carries restrictions for the white sucker fish.