REPORT TO CITY COUNCIL
To:Honorable Mayor and Members of the City Council
From:Jason Simpson, City Manager
Prepared by:Adam Gufarotti, Assistant Director of Lake & Community Operations Date:December 9, 2025
Subject:Lake Water Quality Update and Maintenance Agreement with Moleaer for Nanobubble Barges
Recommendation
Approve and authorize the City Manager to execute the Contractor Services Agreement with Moleaer in an amount not to exceed $275,004 for Nanobubble Barge Maintenance in such final form as approved by the City Attorney and authorize the City Manager to execute change orders not exceeding a 10% contingency of $27,500 for uncertainties and adjustments.
Background
In August 2023, the City Council approved the first comprehensive Lake Management Plan. This plan outlined several science-based strategies to improve water quality and reduce harmful algal blooms.
As part of the plan, the City installed three nanobubble barges. Nanobubbles are extremely small gas bubbles, typically less than 200 nanometers in diameter. Because of their size, they remain suspended in the water column for long periods of time and gradually transfer oxygen into the surrounding water. This increases dissolved oxygen levels, supports healthier aquatic conditions, and helps limit the growth of algae by reducing low-oxygen zones that favor algal dominance.
The plan also included targeted algaecide treatments and applications of Phoslock. Phoslock is a lanthanum-modified clay that binds with phosphorus in the water and sediment. Once bound, the phosphorus becomes unavailable for algal uptake, which reduces the nutrient supply that drives harmful algal blooms.
Moleaer Maintenance Agreement
In addition to the permanent barges, the City purchased a fourth mobile nanobubble trailer. This portable system provides flexibility to treat specific hot spot areas around the lake where water quality conditions may change rapidly or where localized algal activity may occur.
Discussion
Since the City installed the second and third nanobubble barges in October 2024, Lake Elsinore has undergone a marked transformation in water quality. Multiple independent monitoring datasets now show sustained increases in dissolved oxygen (DO) at depths where the lake has historically experienced chronic low or no oxygen. These improvements represent the most stable and oxygen-rich conditions documented in more than two decades. As part of the City’s state grant requirements, a third-party scientific evaluation of the nanobubble barges was completed by GEI Consultants. The City has received the draft report, which is attached for your review.
GEI’s technical analysis demonstrates quantifiable and consistent improvements in DO concentrations following installation and operation of the Moleaer nanobubble oxygenation systems. All five independently collected datasets exhibit similar patterns of DO enhancement, particularly in the near-bottom and mid-water column environments that are most sensitive to oxygen depletion. Localized monitoring near the pilot barge showed DO concentrations increasing from 2–6 mg/L in 2024 to consistently above 6 mg/L in early 2025 at both the barge and 250-foot northwest monitoring site. Monthly average DO values at 5–6 meters depth recorded by EVMWD equipment rose to 8–10 mg/L by late 2024 and remained above the hypoxic threshold during winter and spring 2025; statistically significant increases were also detected during the stratified summer period of 2025, when DO is typically at its annual minimum.
Lake Elsinore is a highly dynamic and complex aquatic system, and its water quality can shift rapidly in response to external environmental factors such as temperature, wind, nutrient inputs, and hydrologic changes. Because of this natural variability, additional scientific work and long- term monitoring are essential to ensure the continued success of the lake’s restoration efforts.
The City remains committed to comprehensive monitoring and adaptive management to better understand how the lake responds to ongoing interventions, including the nanobubble oxygenation systems.
GEI recommends continued lake-wide mapping of near-bottom dissolved oxygen and the installation of a deep-water in-situ sonde located in the coldest and most nutrient-sensitive zone of the lake. These instrumentation enhancements would provide high-resolution, continuous data that capture both spatial and temporal variations in oxygen conditions. Such information will significantly improve the City’s ability to evaluate the long-term performance of the nanobubble technology under varying seasonal and hydrodynamic conditions and will support more precise, evidence-based management decisions for the lake moving forward.
When the nanobubble barges were originally purchased from Moleaer, the capital acquisition cost included both initial installation and maintenance. The current maintenance agreement is set to expire at the end of 2025. Due to the demonstrated success of the nanobubble oxygenation program and the substantial improvements in lake water quality, staff is recommending that the City Council authorize a new maintenance contract with Moleaer. The new agreement would Moleaer Maintenance Agreement
provide ongoing service for all three floating barges as well as the mobile nanobubble trailer unit.
The annual cost of the Maintenance agreement is $275,004.
The most significant maintenance requirement for the barges is the regular cleaning and calibration of the onboard gas generation and delivery systems. Each barge produces its own oxygen supply by compressing ambient air and separating it into concentrated oxygen. Routine maintenance ensures that these systems continue operating efficiently, delivering precise oxygen concentrations and maintaining consistent nanobubble production.
City staff is actively pursuing grant funding to offset operational costs associated with the lake management program. As part of these efforts, the City is positioned to receive $8 million in federal funding to support ongoing lake restoration, pending approval of the federal budget and final signature by the President. This funding would significantly strengthen the City’s ability to sustain long-term water quality improvements and continue advancing the Lake Management Plan.
Fiscal Impact
Funding costs will come from the Measure Z Budget
Attachments
Attachment 1- Moleaer Maintenance Agreement
Exhibit A - Moleaer Maintenance Quote
Attachment 2 – GEI Draft Report
City Manager's Office