Springfield's Lake Accotink, which was emptied last November for dam repairs, will be refilled and opened again for boating after April 15, according to the Fairfax Country Park Authority.

Repairs on the 360-foot earth and concrete dam were to have been completed by March 15, but harsh winiter weather has slowed the $78,000 concrete repair job, said Louis Cable, assistant director of the park authority. A survey of the dam two years ago by the U. S. Army Corps of Engineers showed it was in good condition but needed repairs to minor hairline cracks.

The popular 100-acre lake was acquired by the country in 1964 after nearby Fort Belvoir stopped using it as a water supply and had it declared surplus government property. It is one of the largest man-made lakes in Northern Virginia, exceeded only by the country's Burke Lake and by the privately owned Lake Barcroft, once the water supply for Alexandria.

Lake Accotink Park now contains 476 acres of playing fields and parkland. But the lake itself has been the main attraction as a popular fishing and boating area.

It will be at least a year or two until there are fish large enough to catch, however, since the lake's fish went down the drain - down Accotink Greek through Fort Belvoir to the Potomac - when it was drained last fall. Arrangements already are being made with the Virginia Commission of Game and Inland Fisheries to restock Accotink, Cable said.

Accotink's cruise boat, paddleboats, canoes and rowboats will be back in operation as soon as the lake is filled, Cable said. With the normal spring rainfall it will take only two or three days to refill the lake once the120 repairs are complete.