Is Pleasant River Lake safe to swim?

As of July 22, 2026, Pleasant River Lake in Washington County, Maine carries a swim caution. Satellite imagery measured 74,560 cells/mL of blue-green algae on July 19, 2026, elevated but below the 100,000 cells/mL advisory threshold. Rainfall over the past week totaled 1.0 in, which can wash bacteria and nutrients into the water.

How this read is built

Pleasant River Lake is a lake in Washington County, Maine covering about 1.4 sq mi, the 163rd-largest of the 319 lakes SwimZone monitors in Maine. Satellite imagery measured 74,560 cells/mL of blue-green algae on July 19, 2026, elevated but below the 100,000 cells/mL advisory threshold.

Blue-green algae (cyanobacteria) blooms are most common from midsummer into early fall, when the water is warm, calm, and rich in nutrients from runoff. They can produce toxins that make people sick and can be rapidly fatal to dogs, so skip water that looks green, scummy, or like spilled paint, and keep children and pets out of it.

Over 7 summers of satellite monitoring since 2020, Pleasant River Lake has not reached a blue-green algae advisory level. Conditions can still change quickly, so check the current read before you swim.

It is currently peak season for blue-green algae, when warm, calm water lets blooms form fastest. This water has no recorded advisory-level bloom in its satellite history, which makes it a comparatively steady summer swim spot; conditions still change between samples, so check the current read before you go.

Is it safe to swim in Pleasant River Lake right now?

Pleasant River Lake carries a swim caution today. Satellite imagery measured 74,560 cells/mL of blue-green algae on July 19, 2026, elevated but below the 100,000 cells/mL advisory threshold. Conditions can change quickly with wind, heat, and rain, so check the posted signs and look at the water before you get in.

Does Pleasant River Lake have blue-green algae (cyanobacteria)?

Low levels. Satellite monitoring measured 74,560 cells/mL at Pleasant River Lake on July 19, 2026, below the 100,000 cells/mL advisory threshold. Keep an eye out for surface scum, which can concentrate quickly.

Can dogs swim in Pleasant River Lake?

Use caution. Blue-green algae at Pleasant River Lake are elevated (74,560 cells/mL on July 19, 2026). Dogs are far more sensitive to cyanobacteria than people, so keep them out of the water and away from surface scum.

How often does Pleasant River Lake have blue-green algae blooms?

Over 7 summers of satellite monitoring since 2020, Pleasant River Lake has not reached a blue-green algae advisory level. Conditions can still change quickly, so check the current read before you swim.

How many Maine lakes and beaches are unsafe for swimming today?

Today, 15 Maine waters are above a safe-contact threshold and 33 more warrant caution, out of 457 monitored waters SwimZone tracks in the state.

How is Pleasant River Lake's water quality measured?

SwimZone builds this read from EPA CyAN satellite imagery for blue-green algae, official beach and fecal-bacteria advisories where a program monitors Pleasant River Lake, and a recent-rainfall overlay, all refreshed daily. It was last updated July 22, 2026.

• Blue-green algae and dogs→
• What does blue-green algae look like?→
• When is algae season?→