President Reagan has signed the bill increasing the authorization for the Central Utah Project and providing money to compensate Strawberry Water Users for a land swap, a spokesman for Sen. Jake Garn, R-Utah, said Tuesday. The president was in California campaigning for George Bush.

The measure provides $45 million to keep the CUP going through fiscal 1990, and $15 million for the Strawberry Water Users. It also contained $3 million for pasture rehabilitation near the Strawberry Reservoir.Garn said he is pleased at passage of the CUP extension, and hopeful that a bill can be passed in the next session of Congress to give CUP enough spending authority to complete the project's municipal water and irrigation features.

A CUP reauthorization to provide $750 million to complete the project foundered in Congress this session, and Utah lawmakers attempted, unsuccessfully, to write legislation providing that power revenues in the Upper Colorado Basin finance completion of the project.

Unless the authority limit is expanded, the project could be halted short of completion. All five Utahns in Congress have said they are optimistic that negotiations among the Upper Basin states of Utah, Colorado, Wyoming, and part of New Mexico can develop a basinwide plan for finishing the Upper Basin project, originally authorized in 1956.