HAYDEN LAKE — The number of Harmful Algal Blooms advisories at Hayden Lake has been a growing concern for the Hayden Lake Watershed Improvement District. 

In six of the last 12 years, health advisories have been issued, including in each of the last two summers. 

“They’re starting in early July and lasting throughout the summer and the one we’ve had is still ongoing,” Hayden Lake Watershed Improvement District Director Tom Yount said. “The frequency seems to be increasing and the duration seems to be increasing.” 

To combat this, the district pursued a grant from the Department of Environmental Quality to evaluate nutrient cycling and identify strategies to reduce or prevent HABs.  

Yount compared the warming and cooling of the water’s effect on HABs to an on or off switch for the blooms.

“They are pretty dormant and benign when the temperature cools down and the north end of the lake freezes and it's just after the spring thaw when the water temperature warms up to 60 degrees, it reactivates them and starts the cycle again,” Yount said.  

The district is hiring Montana-based SWCA Environmental Consultants to lead the professional engineering work involved in restoring Hayden Lake and Hayden Creek in the north arm of the lake.   

SWCA will team up with EutroPHIX to evaluate water quality data and lake sediment samples in order to determine mitigation goals and restoration strategies.

“There's not much we can do with those temperature cycles, but what we’re going to try and control are the nutrients, specifically, the amount of phosphorous,” Yount said. “Right now, the majority of phosphorous coming in the system is from Hayden Creek.” 

When people are exposed to cyanobacterial toxins, adverse health effects can range from a mild skin rash to serious illness or in rare circumstances, death.  

“When we have an algal bloom, we warn them not to drink the water. You can’t even boil the water to make it safe,” Yount said.  

To his knowledge, there hasn’t been anybody who’s died from HABs at Hayden Lake, but he’s aware of five dogs passing away due to the effects of HABs.  

“It's the shallow areas of the lake that seem to be threatened that we’ll be paying more attention to going forward and working to try to control these algal blooms,” Yount said. 

Earlier this year, Girl Scout Troop 222, led by scoutmaster Megan Loper removed more than 900 pounds of trash from the Hayden Creek area, including TVs, microwaves, spray foam and paint cans and spent shotgun shells.  

Hayden Creek is the largest tributary to Hayden Lake and can carry contaminants from this type of trash straight to the lake, especially during spring runoff.  

Scouts from Troop 222 and Scouts BSA Troop No. 3 have also removed more than 4,000 pounds of dried plant debris from the shores of Sportsman Park on the north end of Hayden Lake. 

The plant matter was removed to prevent it from re-entering the lake next spring, where it would deposit nutrients back into to the lake.  

    Harmful Algal Blooms (HABs) are visible along the shoreline at Hayden Lake. Hayden Lake Watershed Improvement District is pursuing solutions through Montana-based SWCA Environmental Consultants to combat HABs concerns in the north arm of Hayden Lake and Hayden Creek.