An RMA crew pulled barrels full of dead fish from the surface of Laguna Joaquin Saturday.
[Fourth update, 5:35 p.m. Saturday] Workers spent all day Saturday clearing Laguna Joaquin of hundreds of dead fish, possibly killed by an herbicide used to address a toxic algae bloom there. The Rancho Murieta Association reported the crews, in two boats, finished clearing the lake surface at 5:30 p.m., and they weren't seeing more floating fish.
What happened? At the RMA’s request, the Community Services District used an herbicide to treat a cove at the east side of the lake, where the pump house is located, to keep algae from clogging the pumps, according to Larry Shelton, an RMA director and retired environmental scientist.
Shelton blames the herbicide, which depletes the water's oxygen to kill algae, for killing the fish. “We didn’t anticipate it would have such an effect on the fish,” he said in an interview at Laguna Joaquin Friday evening.
Saturday morning, neighbors out walking stopped to look at the hundreds of dead fish dotting the water and to talk about what happened and what can be done to keep it from happening again.
The neighbors' concern about cleanup was addressed promptly by the RMA, which put two boats in the water. Working with a CSD crew in one of the boats, they had done considerable cleanup of the lake surface by late morning, skimming barrels full of dead fish from the lake.
Rod Hart, the RMA's maintenance manager, said his team had five people on the job, while the CSD had three, including one who was opening fire hydrants in the area, running fresh water through storm drains into the lake, trying to improve its water quality.
Laguna Joaquin’s level has fallen this summer as its influx of fresh water from the Cosumnes River has been interrupted by work on the irrigation ditch that connects the two. The RMA and downstream ranchers rely on water stored at Laguna Joaquin.
A Laguna Joaquin neighbor contacted RanchoMurieta.com Friday evening to report hundreds of fish had died. Shelton, who also lives on the lake, put the number at several dozen, mostly bass, when he spoke Friday night. When the sun came up Saturday, he readily acknowledged the problem was worse than he'd thought. "It's worse in relation to the dead fish," he said. "It's probably not worse in relation to the algae bloom."
A patch of blue-green algae at the edge of Laguna Joaquin. (Photo by Sandra Stadnik)
The algae involved is blue-green algae, or cyanobacteria, which are present in most lakes. Certain conditions – low water levels, limited circulation, more heat or light – can cause the algae to bloom and sometimes release toxins.
Hart said a "perfect storm" of circumstances about 25 years ago caused a similar fish kill in Laguna Joaquin. "The level was down, the algae was bad and there was hot weather," he said, and a by-the-book application of a chemical resulted in a fish kill.
Management of Laguna Joaquin, a detention pond, is a shared responsibilty between RMA and CSD. RMA owns the land under the lake, while CSD is responsible for the water. Shelton said the lake is not a priority for CSD, and he said RMA management of the water might be a better answer.
Dead fish were everywhere on Laguna Joaquin Saturday morning.
Shelton said the irrigation pumps that RMA uses to water common area around Laguna Joaquin have been shut off as a safety precaution until the bloom passes. No water is being sent to ranchers, he said. He also said Laguna Joaquin’s fountains are running 24 hours a day to try to aerate the water.
"At this point," he said Saturday morning, "my attention is on trying to mitigate the appearance and the odor and the health concerns, and then at some point in time we'll just have to figure out what to do in the future – restock the lake, add a couple more pumps, get a better management program on the health of the lake."
He said Sacramento County’s environmental division has been notified, adding that the county can test the lake and direct the CSD’s approach to treat it.
Shelton said Murietans must avoid body contact with the lake because the algae is toxic. If you choose to fish there, he said, be sure to wash your hands.