Replacing Yosemite's 70KV Transmission Line With Great American Outdoors Act Funds

Yosemite National Park used Great American Outdoors Act (GAOA) funds to replace a failing high-voltage transmission line and related electrical equipment serving Yosemite Valley, the Turtleback emergency communications hub and the Wawona Tunnel distribution systems.

The problem

The 5.1-mile line, with its 54 metal towers, insulators and conductors, failed to meet current regulations, and had failing parts and damage from lightning, rockslides, fires and falling trees. Its power provider, Pacific Gas & Electric (PG&E), could have switched off the deficient line; if it failed or were disconnected, park communications would go down and about 20,000 visitors, residents, concessionaires and partners would be affected in summer.

The project

The project would:

• replace the non-compliant 70KV line and update critical electrical components;
• prevent a long outage across Yosemite Valley, the Wawona Tunnel and the Turtleback hub, and cut the valley's several power outages a year;
• keep power, lighting and heat flowing to about 20,000 people, and to central radio and cell towers for emergency communications, including the medical clinic;
• replace damaged, rusted towers that endangered electricians, and remove a serious fire hazard by replacing old equipment and clearing hazardous vegetation;
• correct $9.319 million of deferred maintenance and reduce the cost of constant repairs.

It improves power reliability for the Ahwahnee Hotel, Yosemite Lodge at the Falls, Curry Village, employee housing and the new work at Bridalveil Fall. Bringing the line up to Federal Energy Regulatory Commission and California Public Utilities Commission standards also lets the Park Service reopen talks for the power company to take ownership, and responsibility, for the line.

Status

Declared substantially complete on December 7, 2021. The 90-year-old line powering all of Yosemite Valley received $9 million of GAOA critical repair and replacement funding.

Sources

• National Park Service, Yosemite National Park, "Critical 70KV Transmission Line from Yosemite National Park's Boundary to Highway 140 Powerhouse to be Replaced." https://www.nps.gov/articles/000/gaoa-70kv-transmission-line.htm
• A photograph credited jointly to the Park Service and PG&E is not reproduced here.