Lady Nopamas of the Thai king's court created a lotuslike float of banana leaves, placed a candle on it and carefully put the small offering in the nearby river to thank the water spirits for a successful harvest and the water provided. She probably never thought her act would become a traditional Thai ceremony.

Saturday, that 700-year-old tradition will continue with the Thai-American Association's 15th Annual Loy Krathong Festival at the Lincoln Memorial Reflecting Pool.

In the 12th month of each year, when the moon was full, "friends and spouses would get together to place the Krathongs filled with candles, incense and lotus flowers afloat in the canals and rivers to make a wish to the water spirits," says former association vice president Charlene Day. "The Krathongs would be carried down the river by the currents, and the longer the boat stayed afloat the more chance your wish had of coming true. It's a spiritual regeneration, a sentimental, romantic and artistically beautiful ceremony."

Along with the Krathong ceremony, the festival organizers promise an appearance from Thai Foreign Minister Siddhi Savetsila, a buffet of traditional Thai cuisine, music and dancing by the Thai Cultural and Performing Arts Association.

The program begins at 6 p.m. and reservations are necessary. For more information call 299-2137.