Algae blooming along Yuba River
by Laura brown
Warm temperatures combined with a low water year have encouraged an unwelcome green visitor to infest popular swim holes on the South Yuba River.
Algae blooms are a normal occurrence in rivers and lakes during the summer months and typically do not pose health risks to humans. Some years are worse than others.
“It’s showing up everywhere. We saw similar kinds of stuff in the ’80s,” said John Hiscox of the California Department of Fish and Game.
Swimmers in the Bridgeport area this time of year will see more than the usual amounts of bright green hair-like slime attached to rocks and floating in the shallows.
Though unpleasant, people shouldn’t be concerned.
“The Yuba is a healthy system,” said Jen Hemmert, a watershed monitoring specialist for the South Yuba River Citizens League. “The algae is not going to be something harmful to recreate in or consume.
“It should naturally be in the water. It’s a food source for fish and macroinvertebrate,” he added.
“Algae are photosynthetic. They start to bloom when sunlight increases,” said SYRCL’s river scientist Gary Reedy.
He is concerned that excess algae could rob oxygen from the water and cause swings in pH levels, which could harm fish.
Though some fish deaths related to algae have been reported in private ponds this summer, problems with dissolved oxygen in rivers is uncommon because water is constantly moving, Hiscox said.
Algae needs sunlight, warm temperatures and nutrients such as phosphorous and nitrogen to grow.
This year’s low flows and warm summer temperatures have combined with human-caused nutrient loading, ranging from waste water treatment plants to excess human bodies slathered with sunscreen, to produce the perfect recipe for algae blooms, Reedy said.
Algae has also been known to trigger an increase in dissolved carbon, which fuels the growth of more bacteria that consumes mercury and changes into a form that fish can ingest, Reedy said.
Algae is an indicator of water quality, so SYRCL began a new monitoring program this year, visually surveying three areas along the upper watershed.
Since July, algae has increased below the town of Washington at the confluence of the Yuba River and Poorman’s Creek and below the Spaulding Dam at Lang’s Crossing.
An area below where the Donner Summit Public Utility District discharges effluent into the river also is monitored. This summer the California Regional Water Quality Control Board issued a violation to the district after algae blooms were discovered below the discharge area.
Higher flows released from Spaulding Dam and cleaner water are needed to reduce algae, Reedy said.
“Hopefully we’ll get an early winter,” Hiscox said.
Cold temperature caused by winter rains and snow melt will kill algae, Hiscox said.
On September 22, Nevada Irrigation District will increase flows in Canyon Creek and the South Yuba River from 4 cubic feet per second to 150 cubic feet for five days. Increasing the water volume is part of an insert flow study in an ongoing re-licensing program for the NID’s water projects on the Yuba and Bear rivers.
The flush of water could help remove some of the algae, Hiscox said.
“It will scour it out and move it on down,” he said.
To contact Staff Writer Laura Brown, e-mail email@example.com or call 477-4231.
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