BARCELONA, Spain (AP) _ A rural county in central Virginia with 65,000 people and two public swimming pools is now dead even with Canada, Norway and the host nation, Spain, in the Summer Olympic medals standings - that after leaving Brazil, Belgium and Mongolia in its wake.

''There's no way to explain it,'' Cindy Matern, the aquatics supervisor for Stafford County's recreation department for the past 10 years, screamed excitedly across a buzzing trans-Atlantic phone connection Thursday.

''I certainly can't take any of the credit. So,'' she continued, ''it must be the water.''

As she spoke, Matern looked out over some of that water filling the Curtis Park pool. It was there 14 years ago that Jeff Rouse, as a member of the Ferry Farms Flying Fish Swim Club, launched his career in the very competitive Rappahannock River League.

On Thursday, swimming as a member of the U.S. team in the water of the Piscines Bernat Picornell several thousand miles to the east, Rouse was edged out by Canadian Mark Tewksbury in the final few strokes of the 100-meter backstroke. His silver, however, gave Stafford County its second medal to go with diver Mark Lenzi's gold.

The haul might not end there. Rouse could quite easily bring back at least one more when he swims a leg of the 400 medley relay Friday. And though neither is expected to add to the count, Stafford also supplied two other U.S. Olympians, pistol shooter Roxanne Thompson and modern pentathlon alternate Conrad Adams.

As Rouse was leaving the Barcelona pool, someone ran his good friend Matern's must-be-the-water explanation by him. The 22-year-old Virginian paused to consider it, laughed and then said:

''Must be.''

But don't laugh. That theory is as good as any other.

Stafford County, with rolling hills covering roughly half its 237 square miles and flat farmland the rest, could be folded into New York City almost 50 times. The people there consider nearby Fredricksburg (population 19,000) the big city because they don't have a city incorporated anywhere within their boundaries.

But the county now has more gold medals since the modern Olympics began than Indonesia (population 147.4 million, square miles 575,450), Thailand (44 million, 198,247 square miles) and Colombia (27.8 million, 439,825 square miles) combined. Which is to say none.

The question - which nations produce medal winners and why? - has sparked endless debate but no decisive answers.

A statistical analysis done by Sports Illustrated just prior to the 1988 Summer Games in Seoul showed the two nations which dominated the gold medal count at virtually every Olympics - the United States and the then-Soviet Union - were actually miserable performers when the totals were adjusted for population.

By the magazine's rankings, the most impressive performances of any Olympics were the single gold won in 1964 by the Bahamas (1 medal for every 108,000 people) and the two won by Norway in 1920 (1 per 200,000). Some of the shine comes off those accomplishments, however, when you consider all three medals were won in yachting.

There are some more legitimate wellsprings of Olympic talent: the former East Germany to name one, California for another. In fact, with its affluence, its emphasis on sports and recreation and its year-round climate, the Golden State claimed 15 of the 36 golds won by the United States at Seoul. In fact, had California seceded from the union just prior to the 1988 Summer Games, it would have been fourth-winningest nation overall.

California has plenty of people (almost 30 million) and pools (one of every five families has at least a hot tub). Stafford County has neither.

''I guess if I had to be honest about it,'' Mattern said, making her emotion plain despite the connection, ''it would be the determination of the individuals involved more than anything else.

''Mark's early diving was done on a springboard in a little pool at his subdivision, and remember, he won the gold on a 3-meter board.

''But we've got the kind of involvement here that's hard to match anywhere,'' she continued. ''We had a Rappahannock River League meet here last Saturday with 1,400 swimmers and probably more than 3,000 people here to watch them.''

The league is such an institution in the county that most of the subdivisions have teams. Just as Rouse swam for Ferry Farms, so did Lenzi for Spring Valley. But neither Matern nor any of the old-timers hanging around Curtis Park on Thursday could remember whether they competed against one another in age-group meets.

Both went to Stafford High, where Lenzi distinguished himself as a wrestler and Rouse saw an annual award named in his honor after winning the state title in the 100 backstroke in 1988.

Neither's accomplishments, however, made them swelled heads when they showed up at the McDonald's in the Chatham Shopping Center - ''one of two in the county,'' Matern bragged.

Perhaps that is why about 100 people have dropped into Curtis Park each night this week to sit alongside the pool and watch the Games on two 45-inch televisions and eat Chesapeake Bay blue crabs - donated by Fredricksburg businesses - and cheer like mad.

''And if we could,'' Matern said, ''the whole county would turn out to see them live.''

The funny thing is, Estadi Olimpic, where closing ceremonies will be staged, holds 65,000 people. Same as Stafford County.