Today's opening of a three-month snow and rainmaking effort over Washington state's snowless Cascade Mountain range has touched off a complex and potentially far-reaching battle over who has the right to the precipitation.

Some angry officials here is the drought-ridden Pacific Northwest are calling the Washington rainmaking program "cloud rustling" while other maintain it is no more than a state's legal and historical right to control its weather.

The controversy centers around a $125,000 emergency cloud-seeding program hurriedly passed by the Washington legislature and signed into law last week by Gov. Dixy Lee Ray.

The project got under way here today with the departure for the Cascades of a rented DC-3 loaded with rainmaking chemicals, dry ice and ammonium nitrate. The plane is scheduled to scatter chemicals into clouds over the mountain range until May in an effort to head off a catastrophic drought that threatens to wipe out eastern Washington's billion-dollar wheat and fruit crops.

But the plan has aroused the anger of some Idaho officials. Idaho Attorney General Wayne Kidwell charged after the program began today that Washington's rainmaking will deprive his similarly drought-threatened state of what little water is left in the clouds after they cross the Cascades and arrive over Idaho's parched fields.

In an angry outburst today, Kidwell announced he would go to Washington, D.C., later this week to file lawsuits in two federal courts aimed at stopping the rainmaking. He said he would file one suit with the Supreme Court, charging Washington state with "inverse pollution" by taking rain out of the atmosphere, and the other suit in U.S. District Court, seeking a halt to the cloud seeding because he said it violates federal environmental regulations.

"We have been told by a half dozen experts that we have a case and we've done our legal homework," he said. We want this thing held up until we're sure we won't be deprived of our fair share of the weather that's due us.

A possible snag in Kidwell's plan developed when Idaho Gov. John Evans notified Kidwell by letter that he opposed the proposed suits because he didn't think the cloud seeding would modify Idaho's weather and because Idaho also might seed clouds if the drought continues.

Despite Evans' objections, Kidwell said he still plans to file the suits and will seek to convince the governor to go along. Kidwell, a Republican, and Evans, a Democrat appointed to fill the term of Interior Secretary Cecil D. Andrus, have been political foes for years.

Although 29 states have weather-modification laws, the Idaho lawsuits would be the first attempt in federal court to determine which state is entitled to what portion of the weather, legal experts said.

According to Dr. Ray J. Davis, a weather-modification law specialist at the University of Arizona, proving rain deprivation by cloud seeding is extremely difficult. "It's been impossible to prove up to now," said Davis, "because you can't show that the diminished amount of rain falling in one place has anything to do with cloud seeding upwind."

Weather modification has been taking place in some form since the first federal patent was issued to a chemical rainmaker in 1894. More recent efforts stem from an attempt in 1946 by a General Electric scientist to seed clouds with dry ice.

Since then, said Davis, a variety of cases has been filed over weather modification at the state courts level. Only a handful of state courts have ruled in favor of halting rainmaking efforts. One Texas State court handed down such a ruling in 1959 and a Colorado court halted rainmaking by barley growers four years ago, Davis said.

The drought in the West has brought a surge of interest this year in weather modification. More than a dozen states are involved, with several - among them, Washington, Colorado and Oregon - taking up the practice on a state level for the first time, Davis said.

"Sooner or later there's going to be a need for some kind of federal operational licensing for weather modification," Davis said. He said he is drawing up suggestions for such a plan. The Commerce Department has been studying licensing since last year.

According to a spokesman for "Project Skywater," a federal program investigating the scientific aspects of cloud seeding in Denver, nearly 200 billion tons of water are contained in the atmosphere over the United States on any given day. "No one knows who owns the water in those clouds," the spokesman said. "There isn't even any evidence we can find so far to determine whether cloud seeding in one place will decrease rainfall downwind."

And weather experts are divided over the efficiency of cloud seeding. Those who believe it works say seeding can cause up to 5 per cent of a cloud's moisture to fall as far as 150 miles downwind.

Kidwell said he will proceed with his proposed suits because of the uncertainty surrounding cloud seeding. Weather expert from six universities have indicated an affidavits that weather modification should be held up until all downwind effects are known, Kidwell said. CAPTION: Picture, GOV. DIXY LEE RAY . . . approved $125,000 seeding program