California’s power crisis was downgraded to a stage 2 alert in late February, after running a stage 3 alert for six weeks in a row. The easing was attributed to several plants coming back on line after repairs.

The state had been in a stage 3 alert, meaning it had the authority to impose rolling blackouts, as its electricity reserves hovered near 1.5%. A stage 2 is called when reserves approach 5% .

California state senate has approved legislation that enables the state to take over hydro facilities owned by utilities in exchange for concessions to the cash-strapped firms. Under the proposal California would become one of the largest owners of hydroelectric power in US, and use profit from those plants to borrow as much as US$12B to buy electricity.

The legislation empowers the state to intervene in the power business by taking over Pacific Gas & Electric and Southern California Edison’s hydroelectric plant network, and by entering into long term contracts with power generators to stabilise costs before the energy crisis becomes an economic disaster. Left unanswered by the proposal is whether California will gain control of the hydro plants permanently and who would operate them. The bill still needs approval from the lower house.

Pacific Gas & Electric Co’s hydroelectric system is built on 16 of California’s river basins that span nearly 804km from Eureka to Bakersfield. It can generate up to 3896MW. Its facilities include 175 dams, 68 power houses, 100 reservoirs, 217km of tunnels and 296km of canals.

Southern California Edison provides electricity to more than 4.2M customers over a 129,500km2 service area in coastal, central and southern California. About 90% of its hydroelectric power comes from the 1000MW Big Creek hydroelectric system, a series of four lakes connected by seven rivers and a series of tunnels located 402km north of Los Angeles in the Sierra Nevada. The system includes 26 dams, 23 generating units, six major reservoirs and produces 3.9B kWh per year.

Meanwhile, surveys indicate that the snowpack this year in California’s Sierra mountains is at only 50-60% of the average. A low snowpack means a low spring runoff, which could spell impending power shortages for a state that counts on hydroelectric dams for roughly a quarter of its electricity.