Volunteers flag unusually high phosphorus readings; board questions lab calibration

Presenter 2 explained recent lab results showing nitrogen roughly in the historical range but reported phosphorus numbers much higher than prior years. The presenter said historical phosphorus readings were near 0.01–0.02 mg/L while the Iowa lab reported values in the 0.2–0.5 mg/L range and added, "it's about 16 times what it should be." He said the discrepancy could reflect instrument calibration, contaminated bottles, or lab issues and that he had emailed the lab and planned to follow up before drawing conclusions about lake eutrophication.

Members discussed options: re‑submitting samples, sending existing frozen samples for parallel testing, and finding a lab with more sensitive instrumentation. The Chair and other volunteers emphasized caution before labeling the lake hyper‑eutrophic, noting that a true jump to those phosphorus levels would show obvious, persistent symptoms across the lake. Presenter 2 said he will consult other labs and report back with recommendations on whether to re‑sample or seek a third‑party confirmation.