Spring rains have the river running hard. However, you chose a stiff 6-weight instead, and hearing the river, you realize you made the right choice. Early in the spring, trout and other stream fish do most of their feeding on or near the bottom. They hold deep partly because much of their food supply lies there this time of year and partly to stay out of swift currents. Swollen from winter and spring storms, creeks and rivers throughout the South tend to run quite high this time of year.
Large flies create extra air resistance, which works against the momentum of the fly line.
Heavy flies create an awkward counterbalance against the head of the fly line, which again makes casting more difficult. Big, of course, is a relative term. Saltwater specialists and even bass fishermen would chuckle at the flies that we consider large in the mountains. My big spring flies for trout are No. Gold-Ribbed Hare's Ears tied with heavy beadheads or some other weight.