Is Woodruff Narrows Reservoir safe to swim?

As of July 20, 2026, Woodruff Narrows Reservoir in Uinta County, Wyoming carries a swim caution. Satellite imagery measured 76,705 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 0.2 in, which can wash bacteria and nutrients into the water.

How this read is built

Woodruff Narrows Reservoir is a reservoir in Uinta County, Wyoming. Satellite imagery measured 76,705 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, Woodruff Narrows Reservoir has reached blue-green algae advisory levels in 6 of them, most recently in September 2025. This is a lake that blooms most summers. Its highest recorded reading was 2,585,253 cells/mL in August 2020.

Is it safe to swim in Woodruff Narrows Reservoir right now?

Woodruff Narrows Reservoir carries a swim caution today. Satellite imagery measured 76,705 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 Woodruff Narrows Reservoir have blue-green algae (cyanobacteria)?

Low levels. Satellite monitoring measured 76,705 cells/mL at Woodruff Narrows Reservoir 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 Woodruff Narrows Reservoir?

Use caution. Blue-green algae at Woodruff Narrows Reservoir are elevated (76,705 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 Woodruff Narrows Reservoir have blue-green algae blooms?

Over 7 summers of satellite monitoring since 2020, Woodruff Narrows Reservoir has reached blue-green algae advisory levels in 6 of them, most recently in September 2025. This is a lake that blooms most summers. Its highest recorded reading was 2,585,253 cells/mL in August 2020.

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

Today, 7 Wyoming waters are above a safe-contact threshold and 1 more warrant caution, out of 74 monitored waters SwimZone tracks in the state.

How is Woodruff Narrows Reservoir'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 Woodruff Narrows Reservoir, and a recent-rainfall overlay, all refreshed daily. It was last updated July 20, 2026.