An $81 million power line construction project, the largest ever conducted by Utah Power and Light Co. without subleasing to contractors, is under way in southern Utah. It extends from a substation at Sigurd, Sevier County, to the Nevada border.

Power will be transmitted to Nevada and California, but some of the electrical energy will also be distributed to southern Utah communities, according to Jack Peck, manager of the southern Utah Telluride Region for UP&L.Two companies, UP&L and Nevada Power, are coordinating efforts, the former building the line across Utah and the latter across Nevada. Completion is scheduled for early in 1990.

A pile of gigantic steel poles, ranging in length from 75 to 136 feet, is beginning to build in Monroe, Sevier County, to be used for H-frame towers on the project. The company will use 566 of them as well as 212 lattice-type steel towers and 169 wooden poles.

Peck said crews are working in farmlands during the winter to reduce damage to agricultural properties and will work in other areas during the warmer months.

From Sigurd, where there will be a strategic switching station for electric energy, the 345,000-volt line will extend south and then southwest. It will cross I-15 about 20 miles north of Parowan, Iron County, and then parallel the freeway to Iron Springs. It will then extend in a westerly direction to meet an existing power line owned by the Intermountain Power Agency.

Electrical power form northern and central Utah and the Glen Canyon Dam feeds into the computerized Sigurd substation. It is one of only two substations owned by UP&L where employees are on duty 24 hours a day.

The public utility's southern Utah Telluride Region headquarters are located in Richfield.