Northern Virginians were in the forfront as the United States Olympic team won 12 of the 14 events it entered in the first day of the Holland Cup Regatta on the Bosbaan rowing course today.

The coxed pair of brothers Mark and Fred Borchet of Arlington, Va., with coxswain Chris Wells of Alexandria, proved surprisingly easy victors, clocking 7:28.66 over the 2,000-meter course to finish well into open water ahead of West Germany's Madgeburg Club (7:41.49) and Essen (7:48.06).

The straight pair of Bob Espeseth and Walter (Chip) Lubsen, both of Arlington, was timed in 7:03.34 to win narrowly over West Germany's Lubecker Rowing Club (7:05.47) and Rg Mainz (7:06.86).

Lubsen, a member of the Potomac Boat Club of Washington, D.C., with the other Virginians, also was a member of the victorious American coxed four.

Dan Sayner of the U.S. Naval Academy, Annapolis, Md., competed with the winning four without coxswain.

The high point of the day for the Americans, according to Coach Harry Parker of Harvard University, was the victory of the men's eight, which clocked 5:53.17 and finished one length ahead of East Germany's Dynamo (5:56.83) and Australia (5:57.41).

In all, the American men won seven events and the women five.