The Northern Virginia Regional Park Authority serves two recreation worlds: the activity-hungry who want facilities, and the conservationists who want to leave the land well enough alone.

It merges these two factions into a system that successfully serves more than a million people.

NVRPA was founded nearly two decades ago by conservationists wary of developers' bull-dozers; it is held together in part by funds from jurisdictions lacking their own land for public recreation. Today NVRPA owns more than 7,000 acres, only 10 per cent of it developed for recreation.

The emergence of agencies like NVRPA parallels the post-World II building boom. It marks the flowering of organizations to oversee recreation, the $160 billion national enterprise that is the biggest single industry in the country.

The founders of the NVRPA were conservationists interested in preserving their water supply. That's why NVRPA has concentrated its land acquisitions on the Potomac, Occoquan and Bull Run rivers.

The catalyst that pushed them into a regional recreation agency was need. By 1959, when NVRPA was founded, Arlington, Alexandria and Falls Church were densely populated, lacking adequate parkland and stuck with escalating real estate prices that made large land purchases impossible.

The Groundwork had been laid by conservationists with a single purpose in mind: saving the land. Two members of the current 12-member park board have been there since the founding.

One, 89-year-old Dr. Ira Gabrielson was the first chief of the U.S. Fish and Wildlife Service and is one of the country's most respected conservationists. The other, Walter Mess, a Falls Church mortgage banker, replaced Gabrielson as board chairman last year.

Mess grew up on a six-acre farm in the City of Alexandria. Today that farm is part of a housing subdivision and the pig, dairy and vegetable farms that were nearby have become Landmark Center, a major shopping plaza.

"It wasn't mentality; it was development," said Mess, explaining how demand for public recreation grew. "It was the need for it that didn't exist here because there was so much undeveloped land prior to World War II. Everybody had a big backyard and Alexandria wasn't a city of apartments."

As it became evident these densely-populated areas needed public park land, it also became apparent that Fairfax County was the ideal base for operations. By pooling their money and acquiring some newly available federal funds, NVRPA members could get almost $2.50 value out of every $1 they put up. So the NVRPA was founded.

It provided a regional concept that has worked. All NortherN Virginians today can use the NVRPA's Bull Run, Pohick Bay and Algonkian regional parks. The parks supplement recreation opportunities afforded by Arlington and Fairfax counties, the cities of Alexandria and Fairfax and the incorporated towns.

Indeed, the Northern Virginia Regional Park Authority has no tax base or funding ability of its own. It is dependent on its six members - Arlington County, Fairfax County, Alexandria, Falls Church, Fairfax City and Loudoun County - for financing.

Unlike Maryland, where municipalities like Rockville and Gaithersburg run their own recreation programs independent of Montgomery County, Virginia municipalities such as Fall Church, Vienna and Herndon supplement the county programs with their own.

Thus there is an orderly series in Northern Virginia of park and recreational opportunities. Even Fairfax County, which has two of its own regionalparks, is now concentrating on community and neighborhood facilities.

What has developed in the individual jurisdictions is the concept of big, centralized local recreation centers. Thomas Jefferson and Wakefield Community centers, in Arlington and Fairfax counties, respectively, are the trendsetters. Arlington, one of the nation's smallest counties in land mass, built the Thomas Jefferson center in 1972 in conjunction with a junior high school. It has a 1 1/2-acre gym, game rooms, meeting rooms, arts andcrafts room and a theater that it shares with the junior high. The cost: $6.5 million.

It accomodates all segments of the population and is such a showcase for the county that while the operating money for other centers was cut five per cent for fiscal 1978, the TJ center won a $10,000 increase.

It is a facility for everyone. Businessmen jog around the gym at lunchtime as physical education classes work nearby on gymnastics equipment.

The most recent of big, multipurpose facilities is Wakefield, off Braddock Road near the Beltway in Fairfax County. It was opened in April on 280 acres and provides what recreation planners regard as an ideal set-up: a pleasant park setting with indoor and outdoor activities for the entire family.

Wakefield, which is generating more money than it costs to operate, even has a "preschool crafts center" that serves as baby-sitting outlet.

Despite the immediate success of Wakefield, no more centers will be built on such a grand scale, said Joe downs, director of the Fairfax County Park Authority. The $51.1 million parks referendum that passed June 14 will provide $39 million for smaller neighborhood parks over the next five years, Downs said.

While the political subdivisions are tending to the daily recreation needs of 1 million people, the Northern Virginia Regional Park Authority is providing three facilities - laden regional parks in addition to keeping its original focus on conservation.

Ten years ago NVRPA bought its first building, a $300 tin hut from Sears. When the temperature was 100 degrees outside it was 140 degrees inside where Dave Brown, who has since become NVRPA's operations director, rented boats and sold bait at the Bull Run Marina.

When Northern Virginia residents needed full-fledged regional parks, NVRPA had the land and proceeded to develop them at Bull Run and Pohick Bay, which today can accommodate up to 8,000 people each per day.

The NVRPA also acquired what is now Algonkian Regional Park in Loudoun County in 1976 from the Potomac Electric Power Co., which used the complex as a company recreation area. That site included an 18-hole championship golf course.

Large swimming pools of 17,000 square feet, reportedly the largest in the east, are moneymakers at Bull Run and Pohick Bay. They are designed as recreation pools with mostly shallow water, which NVRPA found brings a greater demand for family use.

And now NVRPA, with a top-notch professional staff, has gone into some innovative concepts of its own:

An environmental studies center at Hemlock Overlook, so named because of its 150-year-old hemlock trees.

The center will give Fairfax County a facility for ecology and environmental science with overnight accommodations in six cabins or dorms that can sleep 20 people each. NVRPA also is cutting costs on the construction by using vocational education students in the county school system.

Rowing facilities on Lake Occoquan and the Potomac.

THe Occoquan facility is being built with donations plus a state grant.Planners expect an increase in scholastic rowing when the facility opens and and a possible bid for the Olympic rowing trails in 1980.

Preliminary plans for the rowing facility on the Potomac near Roosevelt Island feature a boat house with a solar heating system.

Thus what started as a labor of love and concern by conservationists, with foresignt to today's ever-growing demand for recreation needs, today benefits 1 million people, and 90 per cent of the park land is still undeveloped.

"The advantage is that we're reserving things not for 10-50 years from now," said Executive Director Darrell Winslow, "but 100, 200 and even 300 years from now."