Nearly 60 Northern Virginia candidates had filed by yesterday for party nominations for the area's 21 state House of Delegates seats, assuring at least 10 contests in the scheduled Sept. 8 primaries.

Yesterday's 5 p.m. filing deadline brought no surprises. As expected, all 19 of Northern Virginia's incumbent delegates have filed for reelection. The primaries remain threatened, however, because of the continuing court battle over the legislature's redistricting plans.

The primaries will be the first under the new House plan, modified version of which the Justice Department approved this week after reaching a compromise with state legislative leaders. The General Assembly is scheduled to convene Tuesday to consider the compromise, which is not expected to affect Northern Virginia House districts.

The plan, drawn this spring, considerably altered the political complexion of Washington's booming Virginia suburbs. Voters this fall will find a number of races that didn't exist before, as well as other races that didn't survive.

Arlington, for example, four Democratic incumbents have filed for three available seats. Among them is Del Elise B. Heinz, who previously represented both Arlington and Alexandria, but was left without a seat when the legislature abolished her district because of declining population in the inner suburbs.

In Fairfax County, voters will choose delegates in four different districts instead of two. Each district will send three representatives to Richmond -- an addition of two seats to growing Fairfax -- but enough candidates have filed to assure six Democratic and Republican primary contests.

In northeast Fairfax, incumbent Republican Dels. Vincent F. Callahan and Martin H. Perper are being challenged by four other party members for the three available seats. In Southwest Fairfax, Republican incumbents James H. Dillard, Robert E. Harris and Lawrence D. Pratt are in a field of eight for three GOP nominations.

Democrats fielded only two candidates -- one of them incumbent Dorothy S. McDiarmid -- for three seats in Northwest Fairfax. Republican incumbents John S. Buckley and John H. Rust Jr. will face two other challengers there.

Incombent Democrat Earl E. Bell apparently will be unopposed for his party's nomination for Loudoun County's lone House seat.

Following is a list of candidates filing for election to 21 seats in the eight Northern Virginia districts. LOUDOUN Distric 17 one seat Earl E. Bell (D)* ALEXANDRIA District 21 two seats Bernard S. Cohen (D)* Marian Van Landingham (D) David G. Speck (R)* Elizabeth McAnn (R) ARLINGTON District 22 three seats James F. Almand (D)* Elise B. Heinz (D)* Mary A. Marshall (D)* Warren G. Stambaugh (D)* Georgia Delyannis (R) E. J. Jarvis II (R) Sted Lattanzio (R) Michael Steinmetz (R) PRINCE WILLIAM District 23 three seats Floyd C. Bagley (D)* David G. Brickley (D)* Norgorne P. Beville Jr. (D) Robert G. Allen (D) Bill Becker (R) Jack Rollison (R) Smith Young (R) Lori Collier (R) NORTHEAST FAIRFAX District 49 three seats Flora Crater (D) Elaine Lilas (D) Conrad Marshal (D) Nora Squyres (D) Robert Andrews (R) Thomas Cagley (R) Vincent F. Callahan (R)* Gwendalyn Cody (R) Buck Morton (R) Martin H. Perper (R)* NORTHWEST FAIRFAX District 50 three seats Dorothy S. McDiarmid (D)* Ken Plum (D) John S. Buckley (R)* George Landrith (R) John H. Rust Jr. (R)* Meghan Schreiber (R) SOUTHWEST FAIRFAX District 51 three seats Mike Hershman (D) Vivian Watts (D) V. L. Strang Jr. (D) John Adams (R) Robert Brostrom (R) James H. Dillard (R)* Robert E. Harris (R)* Joseph Morrissey (R) Lawrence D. Pratt (R)* Robert Thoburn (R) SOUTHEAST FAIRFAX District 52 three seats Mark Glaser (D) Gladys B. Keating (D)* Brandon O'Hara (D) David Temple (D) Warren E. Barry (R)* Wendell Beban (R) Nelson Jackson (R) Frank Medico (R) Benton Partin (R) *incumbent