MENA — Recent rainfall may have slowed repair work at Lake Wilhelmina, but Arkansas Game and Fish Commission Regional Fisheries Supervisor Andy Yung is pleased with the progress the fisheries team has made in this aging reservoir. Biologists from across the state collaborated to place hundreds of artificial structures and stake beds in the 200-acre west Arkansas fishing hotspot during a large-scale habitat project last December.
“We factored rainfall into the original timeline of the project, so the rising water level wasn’t unforeseen,” Yung said. “Wilhelmina has a large watershed, and the combination of a 14-inch snow melt in January and a few rains have the lake back to full pool. It is small enough that the water should flow out quickly and not disrupt our original timeline for repairs.”
Wilhelmina is in the process of a major repair to the pipes that control the lake’s water level. Leaks in the main outflow pipe have formed between the water-control tower and the dam, causing the lake to slowly drain during summer.
“The problem was first identified in 2019, and we were able to place sandbags over the leaks in 2020 to offer a temporary solution,” Yung said. “Now that funding has been secured, we plan to resleeve the outflow pipe, eliminating the leak, but that requires a complete drawdown of the lake.”
Lowering the water level caused some initial concern with biologists as the lake’s discharge flows into Powell Creek, which is home to a few rare and sensitive aquatic species, including the leopard darter. Although the lake is relatively small, it is deep enough to stratify into a layer of warm, oxygenated water and a bottom layer of colder water with little dissolved oxygen. As water from this lower portion of the water column was released, dissolved oxygen content in the creek downstream could decline, stressing the sensitive species.
“We installed a water-quality gauge downstream of the discharge pipe to keep an eye on dissolved oxygen as we drained the lake,” Yung said.” We also fitted a special cage over the discharge pipe that aerated the water as it passed through. The initial drawdown went very well and we had no incidents that caused any kills or undue stress to the species living in the creek during that initial drawdown.”
Yung says the lake level rises and falls with each rain and subsequent draining, but the risk of lowering oxygen content downstream has decreased significantly as cold weather and flowing water conditions do not allow stratification.
Lake Wilhelmina was the home of the latest state record black crappie, a 5-pound giant caught by an 11-year-old angler in 2011. Add the fact that Yung is a die-hard crappie angler and it was inevitable that AGFC staff would focus on adding fish habitat while waiting for repair work to be complete.
“We’ve placed a lot of artificial structures in the lake in the last two months,” Yung said. “We built 60 Georgia cubes using PVC and irrigation pipe in some of the deeper areas. On one large flat we stacked three to six cubes together to build an offshore reef where there had been virtually no cover for fish to use as shelter and ambush points.”
Crews also created more than 40 log cribs constructed of rough cut timbers.