Stage 1, 2, and 3 Power Alerts Defined

The following definitions are taken from the California Independent System Operator's page:

Stage 1:    Operating reserves are less than minimum. Advise the Utility 
            Distribution Company of potential power shortages and request 
            the UDC to advise end-use customers to reduce demand to minimum 
            requirements without disruption of employment or curtailment of 
            industrial production or commerce. Advise the UDC to prepare for 
            imminent implementation of the interruptible load programs and/or 
            electrical emergency plan.

Stage 2:    Operating reserves are expected to fall below 5%. The UDC 
            will implement interruptible service programs AS DIRECTED BY
            THE ISO and will take all additional actions necessary in 
            preparation for immediate implementation of electrical emergency 
            plans and await further orders from the ISO.

Stage 3:  Operating reserves are expected to fall below 1-1/2%.  The UDC will 
          implement their electrical emergency plan and/or other load dropping 
          to effect 0 MW of involuntary firm demand reductions (i.e., in 
          addition to ALL Interruptible Service reductions) no later than 

The significance of this for us is that, if the ISO calls a Stage 3 power alert, rolling blackouts can occur without warning at any time, anywhere in California (with a few exceptions, but none around here that I know of). A rolling blackout is a loss of electrical power in a limited area for a period of not more than two hours.

A Stage 2 power alert means that certain customers, who have arranged for this ahead of time with the power company in exchange for lower rates, may have their power cut off. UCSC does not have an agreement like this with the power company. However, a Stage 2 power alert may lead to a Stage 3 as the time of peak demand approaches.