Snohomish County Public Utility District No. 1

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Customer Service (M-F 8a-5:30p): 425-783-1000

Load Curtailment Facts

(aka “Rolling Blackouts”)


Rolling blackouts are controlled outages used by power companies to keep the electricity supply and load in balance. These curtailments typically last one to four hours, depending on the severity of the situation and the outside temperature. While California has experienced several rounds of rolling blackouts in recent years, electrical industry experts estimate the current risk in the Northwest is less than one percent.

In the capacity of grid operator for the Snohomish County PUD, Bonneville Power Administration (BPA) must balance customer supply and demand. Under extraordinary circumstances – cold weather, lack of power generation, transmission problems – the PUD could be obligated to curtail load through rolling blackouts if ordered to do so by BPA. While less likely, the governor also has the authority in certain emergency situations to request load curtailment.

The PUD has updated its contingency plan to be prepared for such events. The utility is encouraging all of its customers to consider ways to ensure they’re prepared as well. Utilities throughout the region along with the BPA, meanwhile, are sharing resources, developing protocols and setting up communications systems to protect the needs of their Northwest customers if rolling blackouts become a reality.

Snohomish County PUD’s plan calls for rotating outages through four areas – North County/Camano Island; East County; South County; and Everett. In terms of the timing, the PUD, if ordered by BPA, could have anywhere from several hours of advanced notice to several minutes of warning to no advanced notice at all. Whenever possible, the utility would notify its customers through updates on local radio stations, telephone calls to critical customers and public safety agencies, web sites and other means.


Electricity & Grid Systems

To understand rolling blackouts, you need to understand a few things about electricity and how it’s transported. Electricity is an unusual commodity in that it must be consumed the instant it is produced. In addition:

  • Electrical systems are interconnected via grids (or networks) which transport the electrical energy.
  • Supply of electrical energy in a grid must always match demand (also known as “load shaping”).
  • Grid operators ensure reliability through reserve generation capacity.
  • If reserves fall to critical levels, utilities may be ordered to curtail load and/or protective relays at substations may begin to automatically shed load.
  • The term “rolling blackouts” refers to shifting curtailments between sets of customers to protect the integrity of the entire electrical system.


Events in California & the Northwest

California residents have been hit with several rounds of rolling blackouts in recent years. With conservation and other measures, however, the state is now better managing its energy supplies. 

In Washington, the potential for rolling blackouts in 2001 was created mainly by one of the worst droughts in 72 years and the increase of BPA rates – along with rates for local utility customers – by 46%. Northwest businesses and residents began to conserve both energy and water in significant amounts to save money on bills and help the region.


Snohomish County PUD & BPA

The PUD buys most of its electrical energy from BPA under long-term contracts. The PUD is BPA’s largest public utility customer, receiving power at cost-based rates under the public power provisions of its charter.

As the “grid operator” for PUD, BPA is responsible for balancing customer demand with its supply – power that comes primarily from hydroelectric facilities. Since BPA must balance customer loads and the PUD is in the BPA control area, the utility must curtail load if ordered to do so by BPA. The PUD will do whatever is needed to assist BPA in protecting the integrity of the system for all customers in the Northwest.


Risk of Rolling Blackouts

The current estimates indicate the Northwest faces a less than one percent chance of rolling blackouts. Several factors could contribute to the need for rolling blackouts, including:

  • lack of regional power generation;
  • severe equipment failures;
  • drought conditions in the future, which would limit hydroelectric output;
  • transmission system problems; and
  • extended cold weather and high customer demand.

Regardless of the likelihood of rolling blackouts, the PUD is prepared and has a contingency plan in place. It encourages its customers to take measures to be prepared just in case.


Communication of the Plan

The utility has actively discussed its contingency plans with business customers, municipalities, public safety agencies and other key stakeholders. If the PUD were forced into rolling blackouts it would want customers to be a partner in the process and to be prepared. In addition, the PUD would want customers to recognize that the utility would give as much advanced notice as possible.

PUD employees have received training to ensure that the highest possible service levels are maintained in the event of rolling blackouts.


Regional Efforts

The PUD has worked with other regional utilities and the BPA to ensure a coordinated regional response. The region, for example, is setting communication mechanisms, establishing protocols and sharing information as plans are updated. The PUD is ready to reduce load whenever requested upon by BPA. Meanwhile, area utilities are stepping up their calls for conservation by both business and residential customers. Utilities are also working with businesses that have voluntary load curtailment plans in place.


How do Rolling Blackouts Work?

Rolling blackouts would occur at the request of BPA. Load reductions are achieved by manually opening circuits at substations to stabilize the system so that more widespread blackouts do not occur.

There are four likely scenarios:

  • Immediate Supply Loss – Loss of a major generation source or transmission capacity would cause frequency and/or voltage problems, tripping automatic substation or generation relays causing outages.
  • Immediate Curtailment Order – BPA would order the PUD to curtail load immediately, by opening substation circuits (causing outages) until the load reduction target was met.
  • One Hour’s Notice – BPA would order the PUD to curtail load within an hour, using the same process to achieve the targeted load reduction.
  • Several Hours’ Notice – BPA would order the PUD to curtail load with several hours’ notice, using the same process to achieve the targeted load reduction.


Managing Rolling Blackouts

Curtailments would be rotated throughout the PUD service area so that no one set of customers would bear the entire burden of outages. Each set of outages would last one to four hours, dependent in part on outside temperatures. The outages would be rotated through circuits in four areas (see map):

  • North County/Camano Island
  • East County
  • South County
  • Everett

Circuits serving hospitals and 911 centers would be exempt. The PUD would start in one section, for example in North County, and move through the substations in a sequential order. Once the entire rolling blackout event was completed, the PUD would bookmark where it had stopped, and if another event transpired later (whether in one week or one year later), the utility would start again where it had stopped.


Keeping Customers Informed

Snohomish County PUD would provide regular updates about the timing and locations of outages. Radio is expected to be the best source of such information. The following stations are suggested as resources:

  • KIRO (710 AM)
  • KOMO (1000 AM)
  • KVI (570 AM)
  • KNWX (770 AM)
  • KRKO (1380 AM)

Meanwhile the PUD’s Executive Accounts team would attempt to provide initial notification to critical customers and public safety agencies – 911 centers, municipalities, police, fire, and water and sewage facilities. The PUD would also contact business customers with voluntary load curtailment plans. Information would be available on the PUD’s main phone system and through its website. The utility also is exploring additional means of communicating to customers.


Suggested Customer Preparations

Businesses should check to see if any losses are covered under their existing insurance policies. They may want to consider an insurance rider for additional coverage. Businesses should also ask:

  • What internal policies are in place to reduce damages and/or liability?
  • What about the safety of employees?
  • Are there specific issues related to alarm systems and security?
  • Is the staff prepared in the event of outages? Have you tested your plans?
  • What critical systems would be affected? Should backup power be considered?
  • Have you identified who would power down certain equipment?

For residential customers on life-support and special medical equipment, they need to consider backup systems, much like they do in anticipation of winter storms. If these customers have not ensured operation of the necessary equipment via acquisition of a source of standby power, the PUD recommends that they make arrangements with family or a local agency for relocation to a power source in the event of a disruption to electrical service.

For other residential customers, consider these tips to prepare for outages:

  • Have a battery-operated radio or television so that you can access news reports with the status of rolling blackouts, their expected location and duration.
  • Prepare an emergency kit that includes a flashlight; a wind-up or battery-powered clock; extra batteries; matches; bottled water; and a manual can opener.
  • During an outage, turn off electrical appliances, heat, air conditioning, and equipment – except for one light while waiting for power to return. This lowers the initial demand for electricity and makes it easier for the utility to restore power.

For more information about Snohomish County PUD, and steps you can take during power outages, call Customer Service at 425-783-1000.