FRESNO, Calif. (AP) — Environmental and land preservation groups are concerned about a growing number of solar generating plants being targeted on prime farmland across California's San Joaquin Valley.

The state mandates that one-third of electricity consumed in California must come from renewables by the end of the decade. Already the state has enough solar and other renewables in the pipeline to produce all of the state's power on an average day.

And new projects keep arriving. A survey of county planning departments show roughly 100 proposed for 40,000 acres of farmland across the valley, which would take up as much space as 470 Disneyland theme parks.

Groups such as Defenders of Wildlife and American Farmland Trust says the state needs to do more to direct solar farms to marginal land.