Project Overview
Reservoir Management Background
Site Specifics
System TypePublic drinking water utility
Surface Area13.3 hectare
Average Depth≈ 4 m
Maximum Depth≈ 10.1 m
Volume± 446.2K m3
Primary ConcernRecurrent harmful algae blooms
Management Issues
- Recurrent harmful algae blooms
- Primary species of concern: Microcystis and Woronichinia spp.
- Taste and odor issues led to reliance on well water mid-season
2024 Program Components
- Shock: GreenClean® PRO
- Lock: Phoslock® 5% lanthanum-modified bentonite
- Monitor: in-Situ and LakeTech
- Lab Services: SePRO Corp
Decision Framework
Proactive Reservoir Management Triggers
Target: interrupting the phosphorus cycle.
- Seasonal temperature increase (>12°C) - monitor
- Biological processes drive benthic anoxia - drive aeration system
- Hypolimnetic phosphorus diagenesis - mitigate potential FRP
- CHL-a / BGA-PC production - mitigate chlorophyta and cyanobacteria
- WWTP operations and stakeholders note taste and odor issues - too late
Monitoring
Real-Time Remote Monitoring & Wet Chemistry
Monitoring Array
3x in-Situ Environmental Aqua TROLL 700’s MPS + VuLink telemetry.
Monitoring depths: -3’, -12’, -20’
Readings: taken hourly and uploaded daily.
- pH
- Dissolved oxygen / temperature
- Conductivity
- Chlorophyll-a
- Phycocyanin
Wet Chemistry Program
Quarterly sampling depths: -3’, -12’, -20’
- Turbidity
- Conductivity
- FRP / TP
- CHL-a
- Alkalinity
- Hardness
- Nitrate / Nitrite / TKN / TN
- pH
Program Development
Nutrient Mitigation Program Development
Nutrient Mitigation Calculations
- Targeted reduction of 163 kg TP from sediments
- 2024: 18.12M kg Phoslock®
- 2025: 18.12M kg Phoslock®
- Pre-dose water column phosphorus release considered
- 2.7M kg GreenClean® PRO applied 24 hours prior to each application
- Application rate: 204.5 kg/ha
2024 Shock & Lock Program
- Dormant Microcystis and Woronichinia spp. colonies were the primary species of concern
- Extensive site legacy nutrient dataset available for water and sediment
- Water column phosphorus release addressed through GreenClean® PRO shock treatment
- 24-hour rest period before nutrient lock treatment
Environmental Drivers
2023 vs 2024 Conditions
2023
- Several aeration system outages
- Shorter spring weather with onset of >12°C temperatures by 01 May
- Larger, less frequent precipitation events
2024
- Aeration system mostly operational
- Longer spring weather with onset of >12°C temperatures by 01 June
- Smaller, more frequent precipitation events
2024 Application
Shock & Lock Implementation
30APR24: 204.5 kg/ha GreenClean® PRO applied.
1-3MAY: 18.12M kg Phoslock® 5% lanthanum-modified bentonite applied.
- pH unaffected
- No negative effect in DWTP or risk to non-target macrofauna
- Oxidation reduction potential (ORP) decreased approximately 2 weeks after treatment, then returned to normal
- DWTP noted significantly increased demand for PAC flocculant post-treatment, likely due to bentonite slurry and lysed algal proteins
Results
Wet Chemistry Data
- Samples were sent for laboratory analysis in April, May, July, and September
- Hypolimnion TP values reflected aeration system shutdown and exhaustion of remaining Phoslock® due to legacy load
- TN values remained eutrophic throughout the season with no major change
- Additional parameters not discussed in detail: turbidity, conductivity, FRP, alkalinity, hardness, nitrate/nitrite, and TKN
Results
Dissolved Oxygen, pH/ORP & Sensor-Based Tracking
Results
Chlorophyll-a & Phycocyanin Response
2023 Shock Program
- HAB-targeted treatment focused on Microcystis spp.
- Chlorophyll-a and phycocyanin levels were reduced about 6 weeks after treatment
- Values then climbed throughout the remainder of the season
- Phycocyanin exceeded 2 RFU on 01AUG and exceeded 5 RFU on 15SEP
2024 Shock & Lock Program
- Combined HAB and nutrient mitigation approach
- Chlorophyll-a associated with green algae was largely unaffected in the epilimnion
- Benthic chlorophyll-a levels remained low until late summer and did not exceed 5 RFU
- BGA-PC levels stayed below 1 RFU until 01AUG and remained at or below 2 RFU through 2024
Takeaways
2024 Results & 2025 Goals
2024 Program Results
- CHL-a and BGA-PC levels were far lower in 2024 than in 2023
- Dominant algal species shifted in 2024 from Chlorophyta / Euglenophyta to diatoms
- pH/ORP and TSS monitoring proved highly reliable
2025 Program Goals
- Increase benthic redox potential via aeration system optimization
- Implement a second LMB application
- No HABs and no taste and odor issues in 2025
- No mitigation needed in 2026
