What you can explore
Open the interactive Rivistry dashboard to view available measurements, station context, historical charts, reference lines, and recent weekly highlights for Merrimack River.
Open Merrimack River dashboard →Read the context
River measurements can vary with season, rainfall, temperature, flow, sampling location, and method. Rivistry presents them as evidence to understand and investigate—not as a standalone safety determination.
For the original monitoring information, visit Merrimack River Watershed Council ↗.
River-specific context
An industrial river still being watched
The Merrimack was heavily affected by historic mill and sewage pollution. Modern watershed assessments continue to identify mercury and PCBs among concerns for fish populations, along with flow and thermal pressures.
Industrial growth, raw sewage, paper and textile wastes, and tannery wastes once made the Merrimack one of the region's most polluted rivers.
Mercury, PCBs, temperature, and flow regulation are useful context when interpreting fish, habitat, and river-condition information.
Research source: U.S. Army Corps of Engineers ↗
Keep following changes
Weekly River Updates compare new observations with previous readings, recent baselines, trends, and applicable reference values.
See Weekly River Updates →