Murietans walking around Laguna Joaquin Friday morning saw few dead fish – nothing compared to Thursday morning’s situation – and the Community Services District confirmed that conditions there were improving.
Paul Siebensohn, the CSD’s director of field operations, said the dissolved oxygen readings at the lake were at 1.8 milligrams per liter, much improved from Thursday, when the lake tested at 0.56. A reading below 5.0 is thought to be stressful to fish, and prolonged readings below 2.0 can cause fish kills.
“CIA ditch water continues to flow through Laguna Joaquin,” Siebensohn wrote in an email, “and that water has a dissolved oxygen reading of 8.7 (milligrams per liter). Aerators are continuing to run to help provide oxygen to the water within the basin along with the RMA fountains set to run continuously until the situation improves.”
The theory advanced Thursday for the sudden death of dozens of small bass and bluegill was that algae in the lake had died with the recent cooler weather, and the algae’s death process had taken oxygen from the lake.