New Melones test results for Cyanobacteria

[Steve Molcsan]

Sonora, CA ? Caution signs warning of potentially harmful algae in river waters above New Melones are up as test results show the presence of cyanobacteria.
Last Friday, as reported here, the State Water Resources Control Board issued a warning about a potential harmful algal bloom (HAB) in the Middle Fork of the Stanislaus River upstream of the New Melones reservoir.
This afternoon, lab results on the three water samples found the presence of the cyanobacteria Dolichospermum dominant in the bloom. Another cyanobacteria Aphanizomenon was also noted by Water Board staff in two shoreline collection samples subdominant in the bloom. Although the results did not detect toxins in the blooms, a caution advisory is still being recommended until the bloom subsides.
According to Dr. Keith Bouma-Gregson, an environmental scientist at the Water Board who took part in the sampling, blooms often peak in the summertime. ?We are kind of in prime cyanobacteria bloom season right now, ? he shares. As blooms might last for a few weeks at a time in different places, some of them year-round, he confides that it becomes a cat and mouse game for those monitoring for HABs.
Asked about the greener than normal appearance of the waters at New Melones, which is not under a caution advisory, Bouma-Gregson acknowledges it is algal growth that probably includes cyanobacteria. ?We will keep observing bloom conditions to see if it gets greener or denser and starts to produce toxins or not,? he states.
Earlier today, Tuolumne County Public Health spokesperson Michelle Jachetta shared that the caution signs were posted from the Tuttletown boat ramp all along the river to Camp Nine and the log jam. She also indicated that water samples taken July 24 were drawn at the Parrotts Ferry Bridge, the confluence with Rose Creek, and up at the river log-jam.