Like converging streams, two recent court decisions in California have created new turbulence in the state's ongoing debate over water policy. First, a federal court judge in San Francisco nullified wilderness protection for five northern California rivers - the American, Eel, Klamath, Smith, and Trinity.
Three days later, on Feb. 17, the California Supreme Court ruled that the longstanding and seemingly unlimited right of the Los Angeles Department of Water and Power (LADWP) to water from the Mono Lake basin can be challenged under the common-law doctrine of ''public trust.''
Neither ruling was a complete victory for the ''winners.'' Nor did either mark the end of litigation. But while the wild rivers decision seems likely to be only a temporary setback for environmental interests, the Mono Lake decision could have a significant, long-term effect on California's water future. It already has overshadowed last fall's surprising voter rejection of the Peripheral Canal project to move more northern California water to the south. In fact, attempts to revive the canal project in some form could run head-on into the thrust of the Mono Lake decision.
Two basic conflicts are involved: the transport of huge volumes of water from the state's wet areas, mostly in the north, to its urban populations, large farms, and industries, largely in the arid south; and recreational, scenic, and wildlife preservation values vs. economic growth.
The Mono Lake decision by the California Supreme Court has no immediate, specific effect, but National Audubon Society spokesmen say it will strengthen their arguments in a federal court suit seeking protection for Mono Lake.
The Audubon Society is involved in the Mono Lake dispute because the large, saline body of water east of the Sierras is a major breeding site for California gulls and a way stop for several migrating species. The Los Angeles water department, given the right in 1940 to divert most of the flow from the lake's tributaries into its Owens Valley Aqueduct, has siphoned off so much that Mono Lake's level has dropped some 40 feet. Besides disrupting the ecology of the basin, the water loss has created a broad alkaline flat around the shoreline.
If the new ''public trust'' ruling withstands possible challenges, the Los Angeles Department of Water and Power and other such agencies may have to prove their dams, stream diversions, canals, and other projects are not harmful to conservation and environmental interests.
Also, opponents of such activities will be able to appeal directly to the courts rather than having to go first to the State Water Resources Board. Such appeals to the board, which historically has favored the interests of water users, have tended to be time-consuming and, more often than not, fruitless.
Environmentalists have long contended that agencies such as the Los Angeles water department have ignored opportunities to conserve. Now they say that, under the new court ruling, such agencies may be required to include conservation and environmental impacts in their planning.
Justice Allen Broussard, in the court majority's opinion, states that under the public trust doctrine, ''it is clear some responsible body ought to reconsider the allocation of the waters of the Mono Basin. No vested rights barred such reconsideration.'' While pointing out that the established water rights will not be automatically overridden, he says effects on the environment, on fisheries, and on navigation must be given ''full and continuing consideration.''
In the wild rivers case, US District Judge William A. Ingram set aside federal wilderness designations ordered by then-Secretary of the Interior Cecil Andrus on Jan. 19, 1981, just hours before the end of the Carter administration. Judge Ingram ruled for the plaintiffs - the California Forest Protective Association, the Association of California Water Agencies, the Western Timber Association, and four large timber companies - on the basis of two provisions of the National Environmental Policy Act. He said that Mr. Andrus missed by two days the deadline for filing an environmental impact statement and that the state Legislature had not adopted required management plans for the rivers.
The ruling strips a total of 1,235 miles on the five river courses of federal protection under the Wilderness Act. Portions of the rivers still are protected by the state's wild and scenic river designation, but that can be withdrawn by legislative vote, environmentalists point out.
Interior Secretary James Watt was on the ''right side'' of this issue from the point of view of conservation interests. The Interior Department joined the State of California, the Environmental Defense Fund (EDF), and the Sierra Club in arguing for the wilderness designation.
EDF spokeswoman Patricia Wells said the fund ''will definitely appeal the decision'' and will ''seek a stay'' in the meantime. The Interior Department has not yet announced whether it will appeal.