Dale Wirtz, water division manager for the City of Glendora, presented the city’s third‑quarter water supply outlook and warned of an operational threat from an invasive bivalve commonly called the golden mussel.

Local precipitation and supplies: Wirtz reported 10.8 inches of rainfall at the city water yard for the first half of the water year (Oct. 1–Sept. 30), compared with an annual average near 20 inches measured at that site. He summarized regional water activity: planned deliveries from upper‑district and 3 Valleys accounts are in motion (Wirtz cited 3 Valleys’ plan to deliver a larger tranche in the April–May window), and statewide reservoir storage for California’s 17 largest reservoirs was reported in the 80s percentile range (Wirtz gave a numeric snapshot tied to his slides).

Invasive species risk: Wirtz said water managers are monitoring the golden mussel, an invasive Asian mussel that can attach to intake screens, pipes and turbines and reduce pump and conveyance efficiency. He said the mussel’s presence has been detected further downstream and that managers are evaluating whether additional controls or temporary shutdowns will be needed. “They’re having issues with the golden muscle,” Wirtz said in the presentation (transcript spelling), later clarifying it is an Asian mussel and that officials will provide more detail to the commission in a follow‑up report.

Groundwater and production: Wirtz gave recent groundwater and production numbers: Baldwin Park key‑well groundwater elevations showed a modest decline in recent months; the city produced approximately 751.9 acre‑feet in January, 526.5 acre‑feet in February and 567.8 acre‑feet in March. Wirtz said Colorado River storage (Lake Powell and Lake Mead) was in the low‑30 percent range and that snowpack and Colorado basin conditions were updated in his slides.

Commission questions and follow up: Commissioners asked for more detail about the golden mussel (Wirtz said he will prepare an informational brief) and requested specific delivery totals for the 3 Valleys PM‑26 deliveries; Wirtz said he would obtain the exact numbers and report back. The commission voted unanimously to receive and file the water supply outlook.

Staff emphasized that while the water year showed important deliveries and local groundwater production, the golden mussel presents an operational uncertainty that could affect imported deliveries and pump operations if detections continue.