John M. Dugan, the man who has spearheaded Loudoun County's recent efforts to control and plan for suburban growth, has resigned as director of planning, zoning and community development.

Dugan, 35, has accepted the job of planning director in Sonoma County, Calif., and will oversee a staff of 36 there in July. His salary will be $45,600 a year, $6,000 more than he received in Loudoun.

Sonoma, an agricultural area north of Marin County and San Francisco, is well known among planners because it was the site of the landmark Petaluma case, which asserted the constitutionality of local initiatives to limit urban growth. Dugan said he had been frustrated while working in Loudoun with the dearth of planning laws in Virginia and was attracted to Sonoma because of California's reputation for supporting good planning.

"In California, they have strong planning laws, while in Virginia they don't have any," said Dugan. "It seems that here in Loudoun we know what good planning is but we just can't do it."

Sonoma County Administrator Leonard Whorton said that while Sonoma officials do not consider themselves in the forefront of the antigrowth movement, they are "sensitive to the issues of accommodating housing and protecting the farmland."

Like Loudoun County, Sonoma has a blend of urbanizing areas and fragile farmland. It includes some of the finest vineyards in California. Whorton said that the five-member Sonoma County Board of Supervisors, which voted unanimously last Tuesday to hire Dugan from a pool of 70 candidates, was impressed with his professional qualifications and experience in managing planned growth.

Dugan, who has a masters degree in planning from Harvard University, was hired for Loudoun's top planning job five years ago to beef up the planning staff and rewrite the county's comprehensive plan--tasks the Board of Supervisors hoped would ease Loudoun's transformation into a suburban county and help protect remaining farmland. Dugan said he believes most of that work is now complete and that the staff of 20 he put together will be able to see to the completion of the comprehensive plan.

Board Chairman Thomas S. Dodson (D-Mercer) said he knew Dugan was interested in leaving the county and that he regretted the loss.

"To lose a person of that caliber from our staff is certainly a disappointment," said Dodson. "It will be in the best interests of the county to replace him as quickly as possible, but there will be a nationwide search."