Life-giving streams, with their cool and babbling waters, are a precious resource in arid Utah. That's why some of the most valuable residential real estate is found along their banks.

But city development has encroached on many of these streams, creating soil erosion, damaging water quality and killing off fish. The Salt Lake City government was right, then, to write a new law to preserve City Creek, Red Butte, Emigration and Parleys creeks and the Jordan River from the further onslaught of new housing, patios and decks.

The city has worked for the better part of a year, through many hours of public hearings and an expensive consultant's study, to balance stream protection and private property rights.

We believe that city officials have struck a fair balance in the complicated law for the Riparian Corridor Overlay District. But one state legislator, Rep. Mike Morley, R-Spanish Fork, seems to disagree. He has threatened to write a state law that would strike down the city's creek-protection ordinance and all the work that has gone into it. That would be a mistake, and not just for Salt Lake City.

Because while the capital city's law is a pioneering effort, it's not the only one in the state that sets minimum setbacks for new building next to streams. For example, the east Summit County plan for agricultural protection zones requires a minimum setback of 100 feet from streams.

In general, the Salt Lake City law prohibits new buildings within 50 feet of the annual high water line of a stream, and creates a no-disturbance zone within 25 feet. Existing structures are grandfathered.

But if a property owner believes that the new law would deny all reasonable economic use of the land, the owner can request an exception. The law sets up specific criteria to determine that exception, and it also gives the director of public utilities power to make other, smaller exemptions to the law's requirements for technical reasons.

The owner can appeal a decision to an advisory board and then to district court.

Even within the no-disturbance zone, the law allows owners to maintain existing stairs, landscape walls and paths, permeable patios and decks, or build new ones, with a permit.

Utah's waters are a public resource. They deserve reasonable protection like the city's new ordinance.