Utahns breathed a sigh of relief this week when Congress - nearly at the deadline for adjournment - passed a $45 million bill extending the Central Utah Project for another year, into fiscal 1990. Without such authorization, the project would have had to shut down.

The $45 million was merely a shadow of the original CUP legislation this year. It started out in committee as a $754 million request, was whittled to $420 million, and ran into problems on the House floor.Some members of Congress fought continuation of the project because of its cost. Several of Utah's neighbors raised questions about rights to Upper Colorado River water and the fate of their own water projects. Then there was brief disagreement among members of the Utah congressional delegation about funding, environmental concerns, and payback procedures. All of this combined to put any financing in jeopardy.

By settling for merely extending financing for a year at $45 million, the CUP bill at least guarantees the completion of the Jordanelle Dam and the delivery system to municipal and industrial water users in Salt Lake County.

Even in its drastically reduced form, the measure bounced back and forth between the House and Senate for two weeks as various unrelated amendments were added and dropped. But both houses finally were able to agree on legislation.

That is a real relief. It would have been a disaster for Congress to adjourn and leave the CUP without the ability to proceed. The bill now goes to President Reagan, who is expected to sign in within 10 days.

When a new Congress meets next January, a more comprehensive CUP measure will be introduced to resolve unfinished business and unanswered questions. This time, the Utah congressional delegation should make sure all the members are agreed on what should be done and how it should be paid for. Nothing can kill a proposal faster than lack of unity among its backers.

The CUP has dragged on too long, been delayed too often, and seen costs soar as a result. Let's get it finished as soon as possible.