Many people, especially those under the age of 30, dismiss the blues as an antiquated downer of a genre with no relevance to their lives. D.C. Blues Fest ’99 offers such folk a no-cost chance to test and perhaps discard such preconceptions. Headlining guitarists Lonnie Brooks, Long John Hunter, and Phillip Walker joined together for a recent CD, Lone Star Shootout. On the album’s 15 cuts, these Texas-Louisiana-border club vets, aided by fine rhythm and horn players, astutely mix rough-edged swamp pop, impassioned ballads, and midtempo down-home tales. While these Gulf Coast big poppas dispense some flashy solos, they’re wise enough to keep the emphasis largely on the melodies and beats. They’ll be joined by ’50s-R&B-influenced vocalist Michelle “Evil Gal” Willson, country blues picker Guy Davis, zydeco accordionist Roy Carrier & His Zydeco Rockers, pianist Daryl Davis, and the Blueshounds today from 2:10 to 8 p.m. at Carter Barron Amphitheatre, 4850 Colorado Ave. NW. Free. (202) 828-3028. (Steve Kiviat)