After reports of an influx of mosquitos on the west side of town, City staff began working diligently with Hyperion and County Public Health staff to locate the sources of mosquitos and make every effort to resolve the issue.

Jan. 2 Update: Hyperion staff initiated efforts on Jan. 1 to combat the mosquito influx by making physical inspection of the Hyperion site. As a result of this inspection, they located several mosquito breeding areas and immediately treated them. City staff is coordinating efforts with Hyperion staff and the Los Angeles County West Vector Control District in an attempt to eradicate all the breeding sources for these mosquitos.

Jan. 5 Update: As City staff have been coordinating efforts to address the influx of mosquitoes, Hyperion staff indicated that Los Angeles County West Vector Control District staff would be inspecting the Hyperion site and setting up mosquito traps as early as Jan. 5. Vector Control will return soon after the installation to check the traps and provide Hyperion with a report of their findings by Jan. 9.

Jan. 9 Report from Hyperion:

This report is intended to document the mosquito abatement actions undertaken at the Hyperion Water Reclamation Plant (HWRP) in response to concerns raised by the neighboring El Segundo community regarding an increase in mosquito activity.

In coordination with the Los Angeles County West Vector Control District, Hyperion staff conducted a comprehensive inspection of the plant facilities, the adjacent greenbelt area separating the plant from the residential community, and portions of the nearby neighborhood. The inspection focused on identifying potential mosquito breeding sources, including standing water, vegetation density, drainage conditions, and operational structures that could retain water.

On January 5th, HWRP staff met with William McDougal, General Field Operations Manager of the LLos Angeles County West Vector Control District, to review inspection findings and discuss the action plan for mosquito abatement moving forward.

As a result of these inspections and discussions, the following actions were taken:

• Identification and mitigation of standing water sources within the facility.
• Adjustments to maintenance practices to improve drainage and reduce water retention.
• Coordination with Vector Control to apply appropriate larvicidal treatments where necessary.
• Evaluation of the greenbelt area to ensure it is not contributing to mosquito breeding conditions.
• Continued collaboration with Vector Control to monitor conditions both on-site and in surrounding areas.

These proactive measures identified one area on the north end of Hyperion property that may have contributed to elevated mosquito counts. This area was immediately addressed and mitigated. In addition, new mosquito traps that were set earlier this week are expected to reflect the effectiveness of these corrective actions, and the Los Angeles County West Vector Control District anticipates a significant reduction in mosquito activity. Vector Control also indicated that recent rainfall combined with unusually warm December temperatures was a major contributing factor to the elevated mosquito counts observed in the area. Inspections further identified multiple mosquito breeding sources within the El Segundo residential neighborhood that were contributing to the increased numbers, and these areas were treated directly by Vector Control personnel.

Additionally, County inspectors determined that some specimens submitted as mosquitoes were in fact midge flies, which closely resemble mosquitoes in appearance and can congregate in large numbers at a fast rate. County Vector Control indicated that these insects are commonly associated with wet grass conditions and may be related to moisture present within the greenbelt area, particularly following recent rainfall.

https://www.glamosquito.org/midges

Ongoing coordination with the Los Angeles County West Vector Control District will continue to ensure early detection and prompt response to any future mosquito-related issues. These efforts support not only regulatory compliance but also the health and quality of life of neighboring communities, including El Segundo.

Jan. 13 Update: At the request of City staff, the Hyperion Superintendent and his staff are going to immediately contact the Los Angeles County West Vector Control District to:

• Set up additional and possibly more efficient mosquito traps
• Apply chemicals in addition to the treatments Hyperion staff have already applied
• Take any other mitigating measures possible

City staff also directly contacted the Los Angeles County West Vector Control District Manager's office and requested his full cooperation with Hyperion staff in an attempt to eradicate the mosquitos.

Jan. 15 Update: Yesterday, Los Angeles County West Vector Control District staff re-inspected Hyperion’s green belt area and informed City staff that there were no mosquito larvae or adult mosquitos. As a preventative measure, the area was still chemically treated.

Los Angeles County West Vector Control District has a follow-up meeting with Hyperion staff Jan. 15 to discuss progress made.

City staff and Los Angeles County West Vector Control District staff have received positive feedback from residents indicating that some are seeing a significant decrease in mosquitos.

Jan. 16 Update:

•  Hyperion staff met with Orkin Pest Control Service yesterday to assess the conditions on the Hyperion site.
• Hyperion and Vector Control staff applied pesticide yesterday in the identified breeding areas.
• Hyperion staff are purchasing additional traps that will address both mosquitos and medflies.
• Hyperion is continuing their efforts to eliminate standing water and identify potential additional breeding areas within the Hyperion footprint.
• Hyperion upper management has approved overtime for their staff to work this weekend, if needed.
• Hyperion’s latest Mosquito Report reflects that the numbers have decreased significantly.

Jan. 20 Update:

Los Angeles County West Vector Control District has tested samples collected in the area and found no evidence of West Nile virus.

The following report was provided by Los Angeles County West Vector Control District to Hyperion yesterday, Jan. 19:

This report is a summary of mosquito surveillance and inspection activities in coordination with Hyperion and Los Angeles County West Vector Control District personnel:

On Jan. 15, 2026, mosquito source inspection was carried out on the south side of the Hyperion facilities. Los Angeles County West Vector Control District and Hyperion staff targeted areas that had been identified earlier. During the inspection, Vector Control staff observed that Hyperion had done a good job in pumping and clearing out standing water and have multiple submersible pumps located in large sump pumps with pesticide treatment.

Further, three clarifiers and one emergency final clarifier experienced overflow during that period. All offline facilities were monitored by Hyperion staff and mosquito abatement contractors, drained and pesticide treated. Also, multiple above-ground mosquito breeding and potential mosquito breeding sites were observed during this period, including flooded sites that were created by recent rainfall events. These areas are being addressed by either treatment or by draining. Screen mesh is being implemented at access points throughout the facility to ensure mosquitoes cannot enter.

Los Angeles County West Vector Control District staff continue to attend regular meetings with Hyperion staff to address these issues. Vector Control will continue monitoring mosquito activity to protect public health.

Jan. 20, 3 p.m. Update:

The City just received the following info from Mara Luevano, the Director of Public Works in the Office of Los Angeles Mayor Karen Bass:

• Los Angeles County West Vector Control District and Hyperion staff will set out six additional traps along the greenbelt area between Hyperion and El Segundo this Wednesday, Jan. 21.
• Hyperion staff has been working with the County since this issue was raised in mid-December. Last Thursday, Jan. 15, staff met with LA County to address this issue. County staff returned today, Jan. 20, to continue the mitigation work.
• Los Angeles County West Vector Control District staff have been applying pesticides as needed. Hyperion also has a private contractor on standby to apply pesticide, if needed. Hyperion will purchase and use non-toxic BTI Mosquito Dunks as suggested by the County.

Jan. 21 Update:

Los Angeles County West Vector Control District Executive Director Aaron Arugay provided an update to residents at the Jan. 20 City Council meeting. While his agency continues to work with Hyperion to address the mosquito issue, he encouraged residents to call 310-915-7370 or visit https://www.lawestvector.org/ to schedule a free inspection to address potential mosquito breeding areas on private property.

More information on eliminating mosquito breeding areas from homes and yards is available here (PDF).

Jan. 26 Update:

Last week, Los Angeles County West Vector Control District and Hyperion staff continued their collaboration to mitigate the mosquito influx, targeting mosquito breeding sources. Low-lying areas with standing water were dewatered and were treated chemically. The number of complaints to Vector Control from El Segundo residents has decreased, and the number of mosquitos captured in traps has dropped.

Los Angeles County West Vector Control District and Hyperion staff will continue dewatering low-lying areas with standing water this week and will subsequently apply chemical treatments to these areas.

Feb. 2 Update:

• Hyperion and Vector Control staff continue ongoing work (including overtime on weekends) dewatering standing water in low-lying areas and rooftops, applying pesticides to various areas including catch basin cleanouts, installing mosquito screens at various openings, and identifying and repairing any leaks.
• Hyperion is looking into recruitment of a certified pesticide contractor to help them.
• Hyperion has purchased traps, each of which covers a 1-acre radius area. These traps are to be installed at the Service Water Facility and underground at old digesters.
• Hyperion will initiate the tree trimming starting Feb. 3 on the north end of their greenbelt area.

Please note that it takes a couple of weeks for the chemical treatment of areas under the old digester and other low-lying areas with standing water for a complete positive result.

Feb. 3 Update:

Los Angeles County West Vector Control District has reported to city staff that there has been a significant decrease in the number of mosquitoes collected in traps located in the area of concern for El Segundo. The total trap counts in the area have dropped by approximately 66% in the period from Dec. 18, 2025 to Jan. 29, 2026.

Vector Control will continue to work with Hyperion staff in their efforts to abate any potential mosquito breeding sites as well as respond to any requests for service from El Segundo residents. They can be reached at 310-915-7370 or visit https://www.lawestvector.org/.

Feb. 9 Update:

Saturday and Sunday, Feb. 7 and 8, the Hyperion ground crew started trimming trees and removing excess shrubbery at the north end of the greenbelt. This work will take 2-3 weeks to fully complete, but significant progress has already been made. Workers observed swarms of mosquitoes when entering the area, and the area was subsequently sprayed thoroughly and significantly with a treatment called "Final Feed" which kills the majority of mosquitos within 1-2 days and collapses their populations by over 90% within 2 to 3 weeks.

Dewatering and installation of mesh screening will continue this week. The collaboration with Los Angeles County West Vector Control District to eradicate these mosquitos is ongoing.

Feb. 17 Update:

Mosquito prevention and control tasks completed by Hyperion staff between Feb. 9 and Feb. 15, 2026:

• Tree Trimming: Continued at the exterior greenbelt area from Monday through Sunday.
• Inspections: Conducted mosquito activity inspections throughout the plant.
• Findings & Corrective Actions: Activity was identified in water-filled 40-gallon plastic barrels at the south end of the plant. All barrels were drained and placed upside down. Staff was notified to store these barrels upside down moving forward.
• Maintenance: Street rain gutters were cleaned.
• Installation: Mosquito mesh was installed on B Street between 4th and 6th Streets.

Planned duties for the week of Feb. 17 to Feb. 21, 2026:

• Tree Trimming: Continue at the exterior greenbelt area.
• Inspections: Conduct mosquito activity inspections throughout the plant.
• Installation: Continue installing mosquito mesh as needed.
• Water Extraction: Vactor truck operations scheduled for Friday and Saturday.
• Follow-up: Re-install mosquito mesh in water extraction areas and continue extraction using small pumps on Sunday in areas inaccessible to the Vactor truck.

Feb. 23 Update:

Hyperion completed the following mosquito control and prevention tasks.

• Continued tree trimming at the exterior greenbelt area from Monday of last week through Sunday, Feb. 22.
• Conducted mosquito activity inspections throughout the plant.
• Continued to identify standing water, particularly in areas in close proximity to the old digester and sump pumps.

Maintenance activities:

• Cleaned street rain gutters.
• Began cleaning, washing, and pumping at the primary trenches.
• Installed mosquito mesh on various locations.

Hyperion's planned duties through the next week include:

• Continuing to trim trees in the exterior greenbelt area.
• Conducting ongoing mosquito activity inspections throughout the plant.
• Continuing to install mosquito mesh as needed.
• Scheduling Vactor truck operations for Saturday and Sunday to continue pumping water and cleaning the primary trenches, as needed, and continuing extraction using small pumps in areas inaccessible to the Vactor truck.
• Re-installing mosquito mesh in water extraction areas.

March 2 Update:

Tasks completed by Hyperion:

• Continued trimming trees in the exterior greenbelt area on Monday and Tuesday, Feb. 23-24.
• Conducted mosquito activity inspections throughout.
• Dried standing water around an old digester after repairing plugged floor drains and a non-working sump pump.
• Installed mosquito mesh around the old digester areas.

Hyperion staff also continued maintenance responsibilities:

• Cleaned street rain gutters.
• Pumped water from various locations in the plant's northeast section.
• Continued cleaning and washing out trenches.
• Extracted dirty water, sand, and mud, and performed final cleanup of the vault basement.

Duties planned by Hyperion staff from March 2 - 8:

• Continue trimming trees in the exterior greenbelt area and the northeast section of the plant.
• Conduct ongoing mosquito activity inspections throughout the plant.
• Continue installing mosquito mesh as needed.
• Continue pumping water and cleaning the Primary C and D trenches with a Vactor truck, which is scheduled for Saturday.
• Continue coordinating with LA County West Vector Control to identify and treat the low-lying standing water breeding areas throughout the plant.

City staff have also coordinated with LA County West Vector Control in checking any low-lying standing water areas within the affected segment of the city for treatment.

Updates will be provided as more information becomes available.