Rockville's mayor and City Council adopted a $20.07 million budget for fiscal 1983 that increases property taxes and fees for city services by an average of $76 to individual homeowners and includes $2.9 million in construction funds for roads, parks, a swimming pool and a sauna.

Next year's budget is 6.6 percent higher than this year's spending plan, with the largest increases in the city's environmental services, which include sewer and street beautification services. Although the property tax rate dropped by 5 cents to 90 cents per $100 of assessed property value, the city passed along utility increases that raise the bill for taxes and city services by 10 percent.

For a resident with a $100,000 home, the cost for water services will go to $95.40 from this year's $81. Sewer charges will rise from $132 to $145, and trash pickup fees will increase to $157 from $124. Although the tax rate dropped, the assessments rose, so that a typical Rockville homeowner will pay $443.56, a $16 increase.

The projects in the budget include a new indoor pool, renovations to locker rooms, and a sauna and whirlpool for women in the Rockville Swim Center that will cost about $1 million; a lighted playing field at Broome Athletics Park that has been allocated $190,000; $44,000 worth of artworks for public areas; and more money for roadwork.