Voters in Fairfax, Prince William and Loudoun Counties next Tuesday will decide several proposed bond issues which would finance more school construction and parkland acquisition.

In Fairfax, voters will say yes or no to a $24.9 million school bond referendum and a $51 million park bond referendum.

There will be two questions in the Fairfax school referendum. Voters will be asked whether the county should spend $19,730,000 to build two elementary schools in the Herndon-Reston area; to renew 16 older elementary, intermediate and high schools in the county, and to create two special-education facilities. In addition, they will decide whether the county should spend $5,145,000 to air condition the classrooms and gymnasiums of some of the county's older schools.

If Fairfax voters approve the park bond referendum, the county would spend $39 million over a five-year period acquiring and developing small neighborhood parks ranging in size from one to 30 acres throughout the county. The moneyw ould be used to add such facilities as basketball and badminton courts to the county's 132 existing parks, and in some cases, expand their size.

The rest of the bond money - $12.1 million - would be spent by the Northern-Virginia Regional Park Authority to acquire and develop parkland in Fairfax. Most of this money would be used to help complete a green "buffer zone" along the county's southwestern border at Lake Occoquan and to buy the Washington and Old Dominion Railroad right-of-way running from the Blue Ridge to Alexandria.

In Prince William, voters will decide the fate of a proposed $14.95 million bond issue that would be used for school construction and alterations. Most of the money - $13.35 million - would be used to build the county's sixth high school, to be located between U.S. Rte. 1 and Interstate Rte. 95 north of Dumfries.

According the Prince William officials, the school, if approved, would open in 1980 and accomodate 1,875 students on a year-round basis. Both County Board and school board members have said that if the bond issue fails next week, it will returned to the voters for their consideration again next November.

Loudoun voters will have four bond issues to decide. On the ballot will be a proposed $5.3 million issue for schools, $2 million for improving the county's circuit court facilities, $300,000 to acquire additional land at the county landfill and $400,000 to acquire parkland in the county.

County officials have said that the school money would be used to build elementary schools in Sugarland Run and in Leesburg. If the bond issues fail, they said, both the schools and the court renovations will be financed out of general revenue funds.

Passage of the bond issues, Loudoun officials said, would add two cents per $100 of assessed valuation of the current real estate tax rate of $1.32 this year, and seven cents in later years. If the issues fail, and the county must use general revenue funds instead, officials said that 15 cents would be added to the property tax rate this year, 31 cents next year and 8.5 cents the following year.