NBC correspondent Lee McCarthy is leaving the network after 16 years to become primary anchor for a 10 p.m. news show that is being introduced by WTAF, the independent Channel 29 in Philadelphia operated by the Taft Broadcasting Co. . . .

McCarthy, currently on general assignment for the NBC bureau here, starts work for WTAF Jan. 10, although the news program reportedly doesn't debut until next month . . .

Bureau chief Bob McFarland, in a memo circulated Tuesday announcing McCarthy's decision, praised his "exemplary performance" for the network over the years, citing particularly his coverage of the revolution in Portugal in 1974. At the time, McCarthy was working for NBC-owned Channel 4 here and his work in Portugal earned him a promotion to NBC News . . .

McCarthy is the second NBC bureau correspondent to resign in recent days. On Monday, it was revealed that Emery King was leaving Washington to become an anchor with WDIV, the NBC affiliate in Detroit . . .

McFarland said yesterday that no replacements for the two correspondents had been named . . .

Early in December, longtime CBS and ABC correspondent Sylvia Chase left "20/20" to take an anchor job with KRON in San Francisco . . .

It's probably too early to call such departures from networks for local anchor jobs a "trend," but it's obvious that with all three network news divisions sitting tight on raises and with good pay being offered local anchors in major markets now, there'll probably be more such moves in 1986 . . .

"CBS Evening News With Dan Rather" won the network news race for the week ending Dec. 27 with an 11.9 Nielsen rating and a 24 percent audience share, compared with a 10.8/22 for "ABC World News Tonight With Peter Jennings" and a 10.1/20 for "NBC Nightly News With Tom Brokaw" . . .

Barbara Matusow, former producer at WRC and WJLA and author of "The Evening Stars: The Making of the Network News Anchor," has been named senior editor of the Washington Journalism Review . . .

"The Love Boat," which has been sailing mighty close to Nielsen's Bermuda Triangle most of the season, its ninth on ABC, has been assigned three two-hour specials in 1986-87. But no word on whether it returns as a regular series next fall . . .

"American Almanac," the NBC News magazine, seems to have found the Bermuda Triangle even before it's sailed into a regular slot on the weekly NBC primetime schedule . . .

Keeping in mind that audiences were down Christmas week, the December edition, which aired Monday night, averaged only an 8.0 rating and a 14 share in Nielsen's 12 major markets. In Washington, it managed a 6.2/12 on Channel 4 . . .

Average Christmas week primetime audiences for all three networks were down 4.2 million TV homes (40.8 million to 36.6 million) from the previous week . . . and a full 6.2 million down from two weeks ago . . .

But the holiday doldrums (Airwaves is being a little nautical this morning, TV Column fans) didn't stop No. 1 NBC, reruns and all, from winning another week with a 15.1 Nielsen average and a 26 percent audience share . . .

Second-place CBS was second with a 14.6/25 and third-place ABC was third at 13.0/23 for the week ending Dec. 29 . . .

"Dynasty" continues to slip but ABC found solace in the rise of "The Colbys" spinoff to 21st place last week . . .

In other developments outside the Top 20, the NBC entertainment magazine pilot "Fast Copy" was 25th. However, the good showing, like that of "The Colbys," might have been because it was a fresh broadcast on a week chock-full of repeats . . .

"Superman II" on ABC was 27th, the NBC action drama pilot "Behind Enemy Lines" was 30th and CBS' "Rocky II" rerun was 33rd . . .

Christmas Eve audiences were so low at 8 p.m., ABC's strong Tuesday regular, "Who's the Boss?," slipped to a tie for 39th, up against an "A-Team" repeat on NBC that finished in a four-way tie for 49th and a new episode of "Stir Crazy" on CBS that finished 66th. Keeping in mind that for the week the networks averaged a 42.7 cumulative rating, that first half-hour on Tuesday on all three networks did only a 30.5 . . .

Sliding down the rest of the ratings, CBS' new Wednesday 8-to-9-p.m. entry of "Mary" and "Foley Square" finished 45th and 49th, respectively . . .

"The Kennedy Center Honors" on CBS was part of that four-way tie for 50th and ABC News' ambitious three-hour Saturday night look at "Growing Old in America" was 63rd with a 9.6/17 . . .

That qualified "Growing Old" for the top spot in the Final and if a Lot of People Had Been Watching Probably Fatal Five for the week, followed, in order, by a repeat of "The Black Stallion" on CBS, in 64th place; ABC's "Shadow Chasers"; "Stir Crazy"; and "The Making of Supergirl" on ABC, dead last in 67th . . .