Lynn, Swampscott Continue King’s Beach Bacteria Testing

Lynn and Swampscott are continuing a four-part testing program at King’s Beach and Stacey’s Brook to identify how municipal drainage contributes to recurring bacterial contamination. The work is intended to guide future cleanup investments and help determine whether ultraviolet treatment could be effective.

The city says the 2026 work began in May. The broader testing period runs from April through September, with independent culvert testing planned five days a week during that period.

What the testing will measure

The program combines sediment testing, culvert testing, flow-level monitoring and wet-weather testing. Together, the tests are designed to provide a more detailed picture of how bacteria may move through drainage systems before reaching the beach.

Sediment testing is examining whether deposits inside culverts in Lynn and Swampscott contribute bacteria to discharged drainage flows. That information could help identify whether contamination is tied partly to material that has accumulated inside the drainage system.

Independent culvert testing will collect data five days each week. The schedule is intended to produce repeated measurements across the testing period rather than relying on a single sample.

Flow monitoring will measure bacterial loading by the volume of municipal drainage moving through the system. That approach is meant to show how the amount of water flowing through the drainage network affects the total bacterial load, instead of capturing only the conditions present in one sample.

Wet-weather testing will examine conditions that could affect a future ultraviolet treatment system. In particular, the testing is intended to show when turbidity and flow levels would allow such a system to work and when those conditions could limit its effectiveness.

Data collection and next steps

Kleinfelder is leading daily bacteria data collection at Stacey’s Brook. The results are updated weekly as the work continues.

The effort involves the City of Lynn, the Town of Swampscott, the Lynn Water and Sewer Commission, engineers and the King’s Beach Steering Committee. The collected data will be used to evaluate cleanup steps and possible future UV-treatment options.

The testing is not a final decision to build a UV system. Lynn and Swampscott are expected to use the summer data to determine the next steps for King’s Beach, including whether the information supports moving ahead with additional treatment planning.

The work matters because bacterial contamination can affect the safety and use of the beach. By tracking sediment, drainage volume and weather-related conditions across multiple locations and dates, the municipalities are seeking information that can connect contamination to specific drainage conditions and shape future decisions.

King’s Beach, Stacey’s Brook and Lynn’s culverts and outfalls are among the locations identified in the 2026 testing program. Final 2026 bacteria findings and a decision on a UV system have not yet been published by the city.