Breena Clarke hit the jackpot yesterday--the lottery, a gusher, rainbow's end and Ed McMahon-in-a-tux all rolled into one.

Oprah Winfrey announced on the air that she had selected Clarke's first novel, "River, Cross My Heart," as her October book club selection. The writing life for Clarke, who was born in Washington and graduated from Howard University, may never be the same.

"It's pretty exciting," said Clarke, 48. "I've known for two weeks. It's been pretty tense."

The news is also a shot in the sales charts to Clarke's publisher, Little, Brown. Terry Adams, Clarke's editor at Little, Brown, said 12,000 copies of the hardcover version were published in July. The publishing house was about to go back for a ho-hum second printing when it got the news--about two weeks ago--that Winfrey was bestowing her blessing on it.

Little, Brown pushed up the paperback edition of the book and is printing about 800,000 that will retail for $14.95 a pop. The books are in stores today, Adams said. Cartons were marked "Oprah #27, Do Not Open Until October 14."

The novel tells the story of young Johnnie Mae Bynum and her African American family in Washington in the mid-1920s. When Johnnie Mae and her little sister Clara are prevented from swimming in the public pool in Georgetown, they dive into the Potomac River. Clara is swept underwater near a ghostly rock formation and drowns. Johnnie Mae, her parents and the extended community are forced to struggle with the loss. As the novel unwinds, the reader is taken on a magical history tour of Georgetown and a coming-of-age journey with Johnnie Mae.

Breena Clarke lives in Jersey City and oversees the Editorial Diversity Program at Time Inc. She was not immediately available for comment late yesterday.

Publishers Weekly concluded that "Clarke's scene-building skills are the novel's strengths and occasionally its weaknesses, as each chapter is an intense set piece that sometimes provokes more questions than answers."

Amazon.com reviewer Emily White opined: "Clarke painstakingly tries to re-create this past world, but sometimes it seems her duty to history is holding her back, bogging her down in period-piece details. In the effortless church scenes, history loses its gravity and is absorbed by grace."

But it is Winfrey's review that will send readers running to the bookstore. The Chicago-based talk show host started her book club in September of 1996. An avid reader, Winfrey takes suggestions from her producers, then chooses a book. She tells her viewers about the choice. A month later she discusses the book with a panel of readers and interviews the author. ("River, Cross My Heart" was her 27th selection.) The results are astonishing to a struggling book industry.

Even to a best-selling writer, Winfrey is the kiss of life. "Tara Road" by Maeve Binchy, for instance, had been on major bestseller lists for more than two months when it was named the book club selection last month. There were some 350,000 copies in print.

Since the selection was announced on Sept. 9, "Tara Road" has been selling 50,000 to 100,000 copies a week, said Bantam Dell publicist Barb Burg. Last Sunday it was No. 2 on The Washington Post bestseller list. The big spike will come this weekend, Burg says, because Winfrey discussed the book and interviewed Binchy on Thursday, the day she announced that "River, Cross My Heart" was the next selection.

"When all's said and done," Burg says, "we'll sell over a million copies in hardcover." She said that the show is also sending people to bookstores to read Binchy's 12 other novels.

Another Oprah success story: When the first paperback version of Bret Lott's "Jewel" was published in 1992, Washington Square Press, a division of Pocket Books, printed a measly 14,000. In January of this year, Winfrey selected the Mississippi story for her club and now nearly 1 million copies of "Jewel" are in print, says Melinda Mullin of Pocket Books.

Breena Clarke said that she planned a low-key celebration last night. She and her husband, Helmar Augustus Cooper, were going to stay at home, eat steaks, drink champagne and play with their two Labrador retrievers.

CAPTION: Former Washingtonian Breena Clarke's "River, Cross My Heart" has taken off with Oprah Winfrey's imprimatur.

CAPTION: Breena Clarke, the latest lucky author chosen by Oprah Winfrey.