Final approval has been given to a debt-restructuring plan for financially beleaguered Deseret Generation & Transmission Co-operative.

Last week, the Rural Electrification Administration, the National Rural Utilities Cooperative Finance Corporation and Shell Leasing Company finalized the debt restructuring agreement, which also won approval from the Utah Public Service Commission.The agreement reduces Deseret's debt service and rental obligations on the 400-megawatt Bonanza power plant during the early years and extends the repayment period.

As part of the package, the finance corporation agreed to write off a $13.7 million shortfall involving past payments.

Deseret, which was organized in 1978 by six rural electric cooperatives, has struggled for several years since completing the Bonanza plant near Vernal. The plant was intended to serve a growing electric need in eastern Utah spurred by the rapid grow of oil exploration. But before construction could be completed, the boom passed and the market for the power was gone.

Deseret has attempted to cut losses by selling its surplus on the open market. The cooperative does have firm contracts for sales into the Southern California area but those contracts cannot be put into effect until additional transmission lines are constructed. Those lines are not expected to be available until 1995.

Finalizing the agreement caps a two-year effort to complete the debt restructuring effort.