HARTFORD, Conn. (AP) — Downed trees rather than transmission system problems were largely to blame for widespread power outages during a freak October snowstorm in the Northeast last year, a report by federal regulators and a utility group said Thursday.
The Federal Energy Regulatory Commission and North American Electric Reliability Corp. also said inaccurate weather forecasts led utilities to initially rely on their own crews rather than call for mutual aid, delaying repair work.
The report said that in the Pennsylvania-to-Maine region, 74 transmission lines and 44 transmission substations experienced outages. Those problems caused less than 5 percent of customer outages at the peak of the Oct. 29-30 storm, which left more than 3.2 million homes and businesses without power.
The report said nearly three-quarters of the transmission line outages occurred when trees fell onto power lines, and that many of the trees are beyond utilities' rights-of-way.
Precise measures of the total physical damage to the electrical distribution systems are hard to determine, the report said. But it estimated that 50,000 locations across the Northeast required utility crews to remove trees or repair distribution lines.
The report did not address communications problems between utilities and municipalities. Jette Gebhart, a lawyer at the federal agency, told reporters on a conference call that the report focused on issues related to the Federal Energy Regulatory Commission's jurisdiction and the utility group's reliability standards.
The report also said emergency preparation and response are "almost entirely outside" the regulators' jurisdiction.
Still, it said a review of the impact of utility preparation and response on restoring power "found no indication that inadequate preparation materially hindered restoration of transmission facilities" that are larger and operating at a distance from trees.
The report instead said the problem was primarily with distribution lines, which operate in residential and commercial neighborhoods and were brought down by trees and branches.
The report recommends more tree-cutting and increasing the reporting of outages caused by vegetation.
But the report said standards for inspecting and clearing vegetation required by federal law following the Aug. 14, 2003, blackout in the Northeast and Canada are limited, applying to high-power transmission lines and lower-voltage lines identified as critical to power reliability.
Federal regulators and the utility group said that as a result of the widespread power loss, ISO-New England, operator of the region's grid, imposed a "minimum generation emergency" twice on Oct. 30 to require generators to operate below the minimum level at which it is economical to run.
Marcia Blomberg, a spokeswoman for the Holyoke, Mass.-based ISO-New England, said such emergencies are not uncommon. They are occasionally imposed when demand is very low, such as early morning when appliances are typically not used, she said.
The report said many utilities did not request mutual assistance on the morning of Oct. 29 before the heaviest snow began falling due to a "general understanding" that utilities would be using their own crews, it said.
"However, snowfall amounts exceeded forecasts, and by Saturday afternoon, utilities began to see that more manpower would be required to address the rapidly increasing outages," it said.
Many utilities then began requesting mutual assistance, but "because the storm was so widespread — and demand was so great — there were few regional crews immediately available," regulators and the utility group said.
But restoration of transmission lines was "not materially hampered by inadequate utility preparation or response," it said. More staffing or field crew in advance of the heaviest snowfall would not have significantly improved restoring transmission systems, the report said.
It said there is room for improvement in storm preparedness.