The Division of Water Quality (DWQ) routinely monitors priority lakes, reservoirs, and streams for E. coli as part of its statewide water-quality assessment process. Local health departments (LHD) also monitor priority waterbodies in their jurisdiction, particularly high recreation areas, and submit the sampling results to DWQ. The division compiles these data and contacts the appropriate LHD when samples exceed the maximum water-quality threshold for E. coli.
When a sample is found to be greater than the state’s water-quality criteria, DWQ or its partners assemble a crew to re-sample the site within 24 hours or as soon as possible after the first sample. If the follow-up sample remains greater than the water-quality criteria, the LHD has the authority and discretion to issue a formal advisory. The site is routinely monitored during the health advisory, and the advisory remains in place until four consecutive samples fall below the water-quality health-based threshold.
DWQ provides updates on the current condition of sample sites that exceed the water-quality criteria after two consecutive samples, noting which locations are under formal health advisories and which contain exceedances to the maximum E. coli threshold but aren’t under a formal health advisory by the LHD.
If an advisory is in place, signs will be posted at the lake. DWQ notifies the public on its website when health advisories are lifted.