FALLBROOK, Calif. — The rolling hills of northern San Diego County are flush with brilliant wildflowers and green grasses.

The colors signal that California’s winter — so far — has been wetter than in recent years. They do not signal the end of a three-year-long state drought — nor the seven consecutive years of extremely dry conditions in and around Fallbrook.

“I’ve always figured offshore production would put us out of business, but it could be water,” said Bob Lucy, co-owner of Del Rey Avocado Co. Inc., Fallbrook. “The biggest alligator in the pond is water.”

Compounding the lack of rainfall are court orders that restrict the pumping of Northern California water to cities and farms in the south.

The state’s biggest water contract holder is the Los Angeles-based Metropolitan Water District of Southern California, which in turn provides water at a price to myriad cities and irrigation districts south to the Mexican border and east to San Bernardino.

Projected water rates from the Metropolitan Water District could price growers out of their groves, said Tom Bellamore, president and chief executive officer of the California Avocado Commission, Irvine.

“The problem is particularly acute in San Diego County where growers have been forced to use high salt content water from wells and from the Colorado River,” he said.

Only a heavy rainfall season can leach the salts from the soil, Bellamore said.

Numerous irrigation districts and some city-controlled water authorities have long provided special discount rates for growers, said Steve Taft, president and chief executive officer of Eco-Farm Corp., Temecula. The drawback to the discounted rates is that the water supply is interruptible, he said.

If the district’s water supply is reduced for any reason, growers paying the discounted rates could be cut off, he said.

Depending on the time of year, a cut off could spell disaster. In addition, most districts are eliminating the discounted rates and forcing growers to pay urban rates.

“Avocados need three acre-feet of irrigation water per acre per year,” Taft said.

An acre-foot of water is defined as an acre of one foot deep water, or about 326,000 gallons.

If rates are unchanged, the cost of irrigation water for the average avocado grower in San Diego and Riverside counties can be as high as $3,500 per acre, Lucy said.

If the rates increase, the cost could climb to $5,000, he said.

Such an increase would doom many growers, Lucy said.

“They can’t afford a well either, because the cost of drilling and installing a pump is about $500,000,” he said.

Even if a smaller grower could afford to install a well and a pump, there are other costs, Lucy said. Del Rey Avocado installed a well to irrigate some of its acreage. To rid the well water of harmful salts, the company added a reverse osmosis system at a cost of $150,000, he said.

Urban residents are not immune to the water crisis. The city of Escondido declared a water alert last summer and passed a strict ordinance. Among the restrictions: watering lawns is limited to three nights per week and restaurants may not serve drinking water unless it’s requested by a customer.

The city also established a hot line and urges residents to report water-use violations.

The coastal avocado growing region of Ventura, Santa Barbara and San Luis Obispo counties enjoys cooler year-round temperatures and less severe water problems. It is the southern region that concerns Ross Wileman, vice president of sales and marketing for Mission Produce Inc., Oxnard.

“I’m afraid we’re going to see the combination of encroachment, high farmland costs and a lack of water will reduce growing acreage in the south,” he said.

The one trump card for southern growers is that avocado trees prefer hillside locations so that irrigation water runs through the root systems.

“At least there’s no housing market for developers on those hillsides,” Taft said.