[9] The California Office of Environmental Health Hazard Assessment has issued a safety advisory for any fish caught in Anderson Lake due to elevated levels of mercury and PCBs.

[10] The reservoir was created in 1950 (75 years ago) (1950) by the construction of the Anderson Dam[11] across Coyote Creek in the foothills of the Diablo Mountains east of Morgan Hill.

[12] In January 2009, a preliminary routine seismic study suggested a small chance that a large-magnitude earthquake (6.6 with the dam at the epicenter, or 7.2 up to a mile away) could result in flooding in Morgan Hill and as far away as San Jose.

[17] After years of additional studies and interim actions, the Federal Energy Regulatory Commission dismissed the Water District's plans as insufficient to address the risk of catastrophic failure and ordered on February 20, 2020, that lowering of the reservoir to deadpool storage begin no later than October 1.

The letter noted that the district's "actions to date do not demonstrate an appropriate sense of urgency" regarding the risk of catastrophic failure in the case of an earthquake.

[19] On February 21, 2017, during the 2017 California floods, the reservoir reached as high as 104% of capacity, creating a large flow over the spillway into Coyote Creek, which overflowed and flooded the Rock Springs/Summerside, Olinder, Naglee Park, Roosevelt, Wooster-Tripp and Berryessa neighborhoods of San Jose along US Highway 101 between the reservoir and the south San Francisco Bay.