California Gov. Edmund G. (Jerry) Brown Jr. proposed today that the federal government abandon its limit of 160 acres per farmer for lands receiving federally subsidized irrigation and replace it with a law allowing a 640-acre family farm.

His proposal was greeted warmly by representatives of the Carter administration, which only last summer had announced plans to strictly enforce a 1902 law imposing the 160-acre limit on farmers who receive water from federal reclamation projects.

"I think this is a very constructive apprach to a solution," said Interior Secretary Cecil Ardrus, who earlier this week indicated that the administration was backing off from its original enforcement proposals. "What Governor Brown has proposed is very close to the results of our own hearing on the subject."

Brown also praised Andrus for replacing "confrontation with cooperation" on federal-state water issues in California. This was departure for Brown, who usually has been highly critical of the Carter Administration.

However, other western Democratic governors more than took up the slack today at a meeting with Vice President Mondale, Secretary of Agriculture Bob Bergland and Andrus that capped a seven-state western trip that some have referred to as the "Fritz Blitz."

Governors from Colorado, Oregan, Wyoming, Montana and Utah pressed Mondale and Andrus on federal water policy, saying in effect that they were skeptical of the Vice President's repeated promises that the federal government "will not preempt or interfere with any state or private water right." President Carter made the same pledge in Denver last October.

These promises, said Oregon Gov. Robert Straub, "should clear the air, but the air is not clear in Oregon."

Straub and Colorado Gov. Richard Lamm said they are still fearful that a March announcement of national water policy by Carter could infringe or state rights and practices of allocating water, the most critical resource in the water-short West.

The policy presumably will define the administration's philosophy and attitude toward use of water for agriculture, energy development and other purposes.

Lamm warned that the administration may be painting itself into a corner by its flat and repeated promises that there will be no preemption of any kind. And Utah Gov. Scott Matheson bluntly told Andrus that the western governors believe unanimously that state water rights take precedence over federal or Indian claims.

Indian claims to water rights are a sore point. Montana Gov. Thomas Judge sharply criticized the Justice Department for prosecuting white Montanans in a series of such cases.

Mondale opened his Western swing in Albuquerque last Tuesday by voicing general backing of Indian assertions of treaty rights, but he made no comment on the issue today.

Today's gathering was unusual. All 13 of the governors who attended are Democrats and all come from states carried by Gerald Ford in the 1976 election - Arizona, California, Colorado, Hawaii, Idaho, Montana, Nebraska, Nevada, North Dakota, Oregon, Utah, Washington and Wyoming. Some of the governors face though political fights at home. Others have improved theri own political positions by criticizing the Carter administration, especially on water policy.

Brown, who artfully avoided any criticism of the Carter administration today, made three proposals on the 160-acre limit:

There shoudl be a single federal limit of 640 acres on a family farm, the farmer should be able to lease an additional 640 acres, and he should be charged the cost of the federal water subsidy on the leased land.

The effect would be to accomodate the reality that family farms, on average, are much bigger today than in 1902. But it also would require large agribusiness corporations, which own thousands of acres, to sell off much of their land.

The present 160-acre limit lets a farmer own up to 640 acres if he has a wife and two children. However, birth rates have dropped and a number of farmers in the reclamation areas are childless.

Brown also said that there should be no lottery for disposing of excess land, as originally proposed by Andrus, but that farmers should be allowed to sell it to anyone they choose. Andrus has indicated that the Carter administration already is moving in this direction.

The California governor also called for relaxation of the residency requirement for farmers receiving the federal reclamation water - another move that Andrus favors.

While the residency question can be determined by federal regulation, congressional action would be required for any change in the acreage limitation.

Congressional action also would be necessary for a more modest, "equivalency" proposal advanced earlier in the week by Andrus - a sliding scale that would grant additional acreage to farmers in regions with short growing seasons or poor soil.