Clear Lake LG Sonic Buoy Harmful Algal Bloom Mitigation Project (PL-25-86)

Clear Lake LG Sonic Buoy Harmful Algal Bloom Mitigation Project (PL-25-86)

BACKGROUND: Clear Lake is believed to be the oldest lake in North America at approximately 2.5 million years old. While it is the largest freshwater lake in the State of California, it is contaminated each year with harmful algal blooms (HABs). These blooms occur when certain algae or cyanobacteria grow out of control, fueled by phosphorus nitrogen and warm temperatures. Harmful algal blooms exposure can lead to rashes and neurological, gastrointestinal and liver problems. With 60 percent of Lake County getting its drinking water from Clear Lake and climate change increasing warm temperatures, mitigating the HAB is top priority to ensure a healthy and resilient Lake County. This project focuses on the most severely disadvantaged communities of water purveyors located in the southern arm of the lake. DESCRIPTION OF PROJECT: The Clear Lake LG Sonic Buoy Harmful Algal Bloom Mitigation Project aims to reduce the harmful impacts of nuisance blue-green algae and cyanobacteria, while reducing the processing costs for drinking water purveyors. The proposed 24-month project would include the delivery and installation of 14 algae mitigation buoys from LG Sonic that includes one year of Interactive Algae Control (IAC) software. The system works by utilizing ultrasonic waves that decrease cell buoyancy, blocking access to sunlight by reducing nutrients, which causes algae to sink to the bottom of the lake and die off-thus, reducing bloom frequency and severity. Otherwise, algae floats to the water’s surface for photosynthesis and continues to grow and produce toxins. Ultrasonic algae control is environmentally friendly, stopping algae growth without harming other aquatic life. Construction. A semi-truck would deliver the buoys with equipment to a County owned property near the deployment site. The buoys and equipment will be delivered and loaded onto the boat at Redbud Ramp in Clear Lake (identified on Figure 3), where there are concrete ramps to avoid disturbance to the shoreline. A telehandler will be used to lift and lower the mooring anchor onto the bow of the boat for deployment. A boat (such as a Carolina Skiff) that has either a front or rear deck that flushes (or close to flush) to deploy 225 lb. anchor blocks off would be needed. Once the anchor is loaded onto the deck of boat it would travel to a pre-determined GPS location of where the MPC-Buoy is intended to rest, and the anchor would be safely deployed into the water from the deck of the boat. While deploying the anchor, we will use a GPS map to determine the precise location of the anchor drop. Once a location is agreed upon, the anchor chain is lowered into the water and mooring float tossed out. At this point, the anchor block will be pushed or kicked off the edge of the boat (hence the need for a flush platform). After deployment of the buoys, a boat would be used to maintain the buoys. Construction activities would take approximately 2 to 3 months, and 5 to 6 days per week from 7:00 a.m. to 7:00 p.m. Equipment would be kept at nearby county owned properties. Project activities would begin in 2025 and comply with all Lake County Code requirements. The staging area for the buoys and other equipment would be located at Red Bud Park (a County-owned and maintained facility), located at, 14655 Lakeshore Dr., Clearlake, near the boat ramp in the parking lot near the restroom to the east. The buoys would be a minimum of 650 ft from all shoreline(s). The lakebed disturbance footprint would be limited to the anchor/footings, estimated to be between 3 sq. ft. to 4 sq. ft. Each block is roughly 2 ft x 1.5 ft. of which the anchor is connected to. The location of the buoys will be within the main body of the lake where the water is too deep for tules to reside. Work would be completed with a telehandler and from a boat to avoid impacts to the lakebed. Operation. Project operations are scheduled to take 24 months. The 24-month project includes the purchase, delivery and installation of 14 algae mitigation buoys form LG Sonic that includes one year of Interactive Algae Control software. The system works by utilizing ultrasonic waves that decrease cell buoyancy, blocking access to sunlight by reducing nutrients, which cause algae to sink to the bottom of the lake and die off-thus , reducing bloom frequence and severity. Otherwise, algae floats to the water’s surface for photosynthesis and continues to grow and produce toxins. Ultrasonic algae control is environmentally friendly, stopping algae growth without harming other aquatic life. After deployment of the buoys, a boat would be used to maintain the buoys. For safety, the buoys have flashing lights, and the Lake County Water Resources Department is also considering adding additional lights or flags. Long-term operations and maintenance of the project will be provided by the Lake County Water Resources Department. CDBG-MIT-RIP funds will cover the initial installation, set up costs, and one year of software. At the close of the project, approximately 24 months after construction initiation, the Lake County Water Resources Department will assume full System ownership with ongoing expanses of annul software/SIM care and maintenance fees. These expenses are projected to be funded through the retargeting of existing financial resources as part of the department’s annual budget. The department will continue to seek grant funds to expand the project to other parts of the lake. One identified opportunity is the EPA Community Change grant. Figure 2 includes an aerial imagery of the site with buoy locations. NEPA. The project has received grant funding from the CA Department of the Department of Housing and Community Development (HCD) under the Mitigation Resilient Infrastructure Program (MIT-RIP), which comes from the U.S. Department of Housing and Urban Development (HUD). As such, environmental review under the National Environmental Policy Act (NEPA) is required. In accordance with NEPA, an Environmental Assessment and Finding of No Significant Impact for the project has been approved by HCD/HUD on April 17, 2026, and a request to release the grant funds was submitted to HCD on April 22, 2026.

unincorporated

Lake

Countywide

Lake