A walk along the Charles is almost perfect dog territory.
Long paths, grass, river views and enough activity to make the whole route feel interesting.
Right now, dog owners need one extra piece of information before heading there.
An active cyanobacteria advisory covers part of the Charles River Lower Basin, and Boston health officials are specifically asking pet owners to keep dogs away from the affected water, shoreline and visible algae.
Dogs can be exposed without swimming
The risk comes from more than getting into the river.
Dogs can drink affected water, eat algae scum along the shore or get algae onto their fur and later ingest it while grooming.
BPHC says pets have become sick after exposure to harmful algae, and canine deaths have been documented in Massachusetts and other states after harmful algae were ingested.
That makes the current advisory especially relevant for dogs that naturally head toward the water during walks.
Bring drinking water for your dog and keep it away from the river’s edge while the advisory remains active.
Know the signs after possible exposure
BPHC says to call a veterinarian immediately if a pet has been around an algae bloom and then develops symptoms such as:
Vomiting. Staggering. Drooling. Convulsions.
Symptoms can appear soon after exposure.
If your dog comes into contact with the affected water or algae, BPHC advises rinsing the animal off immediately.
Cyanobacteria blooms can develop during summer and fall, which means they can overlap with the time of year when many new students and residents are starting to use the Charles regularly.
The walk can stay in the routine
The current advisory is about contact with the affected water, shoreline and algae.
It does not mean every riverfront walk is off the table.
Keep your dog on the land-side paths, away from the affected shoreline, water and visible algae, and bring fresh drinking water so there is no reason to head toward the river for a drink.
That small adjustment matters because the Charles quickly becomes part of the routine for a lot of Boston dog owners.
For now:
Bring the leash. Bring the water bottle. Keep the dog away from the river’s edge.
Let the views handle the rest.
The Charles River cyanobacteria advisory and pet-safety guidance were checked on September 1, 2026 using current Boston Public Health Commission and Massachusetts Department of Conservation and Recreation guidance. The advisory remains in effect until further notice, and conditions can change.