Ocean Shores consultants report high phosphorus, propose targeted units and tools to curb toxic algae

Katie Sweeney Rodriguez, an environmental scientist with Herrera Environmental Consultants, told a public meeting in Ocean Shores that a year of monitoring shows the city’s lakes and canals remain nutrient-rich and prone to cyanobacteria (toxic algal) blooms despite improvements since the 1990s.

“This project is to develop a plan for improving the water quality and the fresh waterways of Ocean Shores,” Sweeney Rodriguez said, summarizing the purpose of Herrera’s fresh waterways management work for the city.

Herrera’s preliminary monitoring (summer–fall 2024 plus early 2025 sampling) revisited sites from a 1994 KCM study and added additional lake, canal and watershed stations. The consultant measured temperature, dissolved oxygen, pH, total phosphorus, chlorophyll a, Secchi depth (water clarity), cyanobacteria species and, at watershed sites, E. coli, total suspended solids, chloride and flow. Herrera reported: chlorophyll a values in 2024 generally fell in the eutrophic range (2024 site range: about 1–26 µg/L versus 1994 range of about 10–32 µg/L); total phosphorus remained high at many sites (1990s site averages ranged roughly 50–2,000 µg/L; 2024 averages roughly 59–1,000 µg/L at monitored stations); and the system overall remains eutrophic to hyper-eutrophic.

Herrera detected cyanobacteria species across multiple waterbodies and tested four bloom samples for cyanotoxins. Microcystin was detected in samples from the Lake Menard area…