A population of Spring Chinook salmon broodstock experienced a significant mortality event while they were being held prior to spawning. The fish were being held in two raceways fed by surface water at a hatchery in Eastern Washington. Affected fish were lethargic and swimming at the surface before dying suddenly. On examination, the fish were almost ready to spawn, in good body condition but they had white to yellow tipped gills. Microscopic examination of the gills revealed numerous long flexing rod bacteria arranged in haystacks. The surviving fish were treated with Chloramine-T, a recently approved drug for use in aquaculture, the raceways were switched to well water to decrease the water temperature, and the oxygenation in the raceways was increased. Although mortality was high, some fish successfully made it to spawning with treatment. This case report discusses examination of aquacultured fish as well as potential additional treatments and prevention of Flavobacterium columnare infections in Spring Chinook salmon.