CASE STUDIES
Willard Peak Pond
A phosphorus mitigation treatment to address harmful algal blooms
THE CHALLENGE
Recurring Algal Blooms Restrict Community Recreation
During its first three swimming seasons, Willard Peak Pond was frequently placed under water-quality advisories due to the harmful algal blooms and elevated E. coli concentrations.
Sediment sampling completed in October 2025 identified excess releasable phosphorus stored within the pond’s sediments as a key contributor to the blooms. During warm conditions, this phosphorus can be released into the water column, fueling the growth cyanobacteria-commonly known as blue-green algae. Certain types of cyanobacteria can produce toxin that threaten people, pets, wildlife, and the overall health of the aquatic ecosystem.
Sediment sampling completed in October 2025 identified excess releasable phosphorus stored within the pond’s sediments as a key contributor to the blooms. During warm conditions, this phosphorus can be released into the water column, fueling the growth cyanobacteria-commonly known as blue-green algae. Certain types of cyanobacteria can produce toxin that threaten people, pets, wildlife, and the overall health of the aquatic ecosystem.
THE APPROACH
Targeting Phosphorus At It’s Source
Utah State Parks partnered with EutroPHIX, a division of SePRO, to implement a science-based sediment phosphorus mitigation program. With more than 30 years of experience restoring lakes and ponds, EutroPHIX developed a targeted treatment strategy based on the pond’s sediment conditions.
In spring 2026, approximately 12,000 pounds of EutroSORB® G—a 10% lanthanum-modified bentonite clay—was applied to the pond. The treatment was designed to permanently bind approximately one-third of the estimated releasable phosphorus stored in the sediments, making it unavailable to support future algal growth.
The treatment was supported by a comprehensive monitoring program that included:
In spring 2026, approximately 12,000 pounds of EutroSORB® G—a 10% lanthanum-modified bentonite clay—was applied to the pond. The treatment was designed to permanently bind approximately one-third of the estimated releasable phosphorus stored in the sediments, making it unavailable to support future algal growth.
The treatment was supported by a comprehensive monitoring program that included:
- Monthly water sampling
- A floating NuLAB buoy prototype measuring surface and bottom nutrients approximately every six hours
- A co-located sonde monitoring temperature, dissolved oxygen, pH, and algal fluorescence
- Satellite imagery tracking bloom development and timing
1 of 4
2 of 4
3 of 4
4 of 4
Rapid Water-Quality Improvements Following Treatment
Preliminary results from the first 10 weeks showed a rapid and sustained improvement in water quality following the EutroSORB G application.
42
%
Phosphorus reduction at the water’s surface
36
%
Phosphorus reduction near the pond bottom
LOOKING AHEAD
Building a Phased Path Toward Long-Term Pond Health
Water-quality monitoring will continue through October 2026. Additional sediment sampling will then evaluate how much releasable phosphorus has been converted into permanently bound forms.
Continued restoration efforts will focus on reducing the recurrence of harmful algal blooms, improving recreational access, supporting tourism, and protecting the long-term environmental health of Willard Peak Pond.
Continued restoration efforts will focus on reducing the recurrence of harmful algal blooms, improving recreational access, supporting tourism, and protecting the long-term environmental health of Willard Peak Pond.
RELATED CASE STUDIES
A comprehensive phosphorus management strategy reduced nutrient loading, improved water quality, and prevented risk advisories during peak recreation season.
A targeted phosphorus inactivation program delivered lasting water quality improvements
