Denton proposes simpler mosquito-risk system and quicker spraying based on trap results

Michael Gagne of Environmental Services presented a proposed update to Denton—s mosquito surveillance and response plan that would simplify risk levels and speed response by relying on trap positives instead of delayed human-case reporting. Gagne said testing mosquito samples typically takes 5—7 days, while human case reporting can lag up to six weeks, so the updated plan would use a three-level system and authorize staff to "consider spraying" when one trap location tests positive two consecutive weeks.

Under the proposal, the city would start each season at risk level 1, elevate to level 2 on a confirmed city trap positive, and move to level 3 if a trap location is positive for two consecutive weeks. Gagne emphasized the city—s focus on disease-transmission control (not nuisance spraying), targeted communication (social media, Nextdoor, robocalls and signage), and source-reduction measures; staff will continue to provide larvicides to residents free of charge.

Council members asked about the last spray (noting the city has not sprayed since 2020), how far spray areas extend (Gagne said roughly 0.25 mile in some residential areas and up to about 1 mile in dense street grids), environmental monitoring, licensing and costs. Gagne said monitoring costs are roughly $25,000 per year and a spray-night with a third-party applicator typically costs less than $1,000. Council gave staff direction to update the plan; several council members asked staff to monitor environmental impacts and to return with additional information if needed.