The torrent of water — like an uncapped fire hydrant that was flowing high above Spring Creek — may look like a water park feature, but it's actually helping fish survive.
Black Hills National Forest officials opened the valve early this summer to divert cold water from the bottom of Sheridan Lake to lower sections of Spring Creek in hopes of improving the trout fishery. The valve was turned off on Thursday.
The massive flow was hard to miss while hiking along the popular Spring Creek trail. Around a half-mile in, hikers could hear the crashing of a constant stream of water more than 30 feet up into the creek below.
Black Hills National Forest Fisheries Biologist Steve Hirtzel said that trout need cold water to survive, but on low-flow years water temperatures on some sections of Spring Creek can heat up during the summer months, causing die-off. By diverting the water half a mile downstream of the dam, official think trout will be able to survive through the warm summer months and be able to winter in the creek.
"What we are hoping for is the wintertime carryover of the population; that is what will make it a sustaining fishery," Hirtzel said.
Instead of water flowing over the spillway, it was being diverted through a tube that starts at the bottom of the Sheridan Lake Dam and ends about a half-mile downstream high above Spring Creek.
"The highest priority is to maintain the pool level of Sheridan Lake, so we aren't actually letting out any extra water than what normally would be," Hirtzel said.
The diversion pipe installed with Sheridan Lake was constructed between 1938 and 1940. Hirtzel said the valve has only been open for short periods of times over the last 10 to 15 years to perform routine maintenance.
While the water coming out of the diversion pipe does have a sulfur smell, Hirtzel said it is perfectly safe to swim in and is healthy for the fish, also. South Dakota Game, Fish & Parks and state Department of Natural Resources officials have been out to test the water coming from the diversion pipe for contaminates.
Because the water is being pulled from the bottom of Sheridan Lake, it has stagnated and has more particulates than water near the surface. That stagnation causes the water to have a sulfur smell.
Officials aren't sure yet if the extra release is working, for a few reasons. First, heavy rains that inundated the Black Hills this summer have lessened the need for extra cold water as Spring Creek flows remain high. Also, the Forest Service plans on running this diversion for several summers in order to get more accurate data.