'This is more than I could ever imagine,' said Couch, who took home $112,500 for the win. 'I started off the year so bad. I've worked hard for this. It hasn't hit me yet but I'm sure it will tomorrow.'
D.J. Brigman holed a key birdie putt on the 18th green to finish alone in second place at 15-under-par 273 and earn his PGA Tour card for 2004 by placing in the top 20 on the 2003 Nationwide Tour money list.
Couch used a brilliant performance on Saturday on the Senator Course at Capitol Hill to open a four-shot advantage on the field. He struggled early with two straight bogeys from the par-5 fifth on Sunday, but landed his second shot inside 12 feet at the par-5 eighth and drained the putt for an eagle.
The 30-year-old kept plugging along and found trouble with a bogey at the 13th. At the par-4 14th, Couch hit his approach to five feet and ran home the birdie putt.
Couch added a birdie at the par-5 17th and closed with a bogey at the last, but the victory was never in doubt.
Couch, who earned his third career victory on the Nationwide Tour, will return to the PGA Tour for the first time since 1999.
Brigman worked his way into the picture in the race for a PGA Tour card with a victory at the Permian Basin Charity Golf Classic in October. He needed a strong finish on Sunday to stand a chance at earning the exemption.
The 27-year-old picked up a birdie and a bogey on the front nine to make the turn at 11 under before catching fire on the inward half.
Brigman birdied the 11th and added a birdie at the 14th to reach 13 under. He then birdied the par-5 17th to move into a tie for second.
At the par-4 last, Brigman landed his second shot inside 12 feet and rolled in the putt to take second place outright.
'This is just a dream come true for me,' said an emotional Brigman. 'I just stayed focused. I knew I had to keep pushing on the accelerator. This is absolutely the best round of golf I've ever played, given the pressure and the circumstances.'
Zach Johnson, who earned the top spot on the 2003 money list, shot a 68 to finish alone in third place at 14-under-par 274.
Ken Duke was one shot further back at 13-under-par 275 but came up short in the quest for a PGA Tour card.
Bo Van Pelt and Jason Bohn tied for fifth place at 12-under-par 276. Both players finished in the top 20 on the money list and will advance to the PGA Tour next year.
Jess Daley ended alone in seventh place at 11-under-par 277. Mark Hensby finished one shot further back at 10-under-par 278 to earn his PGA Tour card.
Hensby was joined by Jeff Freeman, Chris Tidland and Wes Short in a tie for eighth.
The following players also earned their 2004 PGA Tour cards by finishing in the top 20 on the money list: Joe Ogilvie, Tom Carter, Ryan Palmer, Tripp Isenhour, Jason Dufner, Vaughn Taylor, Blaine McCallister, Andre Stolz, Guy Boros, Ted Purdy, Lucas Glover, David Morland IV, Craig Bowden and Tommy Tolles.