The Iowa Department of Natural Resources (DNR) is planning a repeat of a successful restoration effort on Diamond Lake in Dickinson County. The DNR will lower the water level in the lake through this fall and winter to eliminate problem fish.
The DNR has relaxed fishing regulations on Diamond Lake from now until April 1, 2018, to allow anglers to more freely harvest game fish before the lake is renovated this fall. Anglers may take fish from Diamond Lake using alternative methods such as nets. The use of explosives, chemicals, or stupefying substances is prohibited. Access to the lake will become increasingly difficult with receding water levels and dense aquatic vegetation.
Diamond Lake was one of Iowa’s first shallow lake restoration projects.
Beginning in 2006, water levels in this six feet deep natural lake were lowered to encourage aquatic plant growth and to eliminate problem fish species that can negatively impact water quality and habitat. In 2009, the lake was refilled with water and native fish species were restocked. Waterfowl use increased nearly 40 fold and northern pike and perch numbers quickly boomed in the clear productive waters. Other wildlife species also took advantage of the newly created habitat and improved water quality.
Since 2009, common carp and bullhead numbers have increased and some indicators of water quality are diminishing. The DNR will repeat efforts made a decade ago to maintain Diamond Lake’s health. The project should move much more quickly this time with fish restocking and water levels returning in 2018.
“All of the partners that worked initially on this project knew we would need to repeat it in the future,” said Mike Hawkins, DNR fisheries biologist. “We were hoping for 8-10 years between resets, and it looks like that estimate was very close.”
DNR wildlife biologist, Chris LaRue, agreed.
“Some of the water quality parameters we examine to track the health of the lake are showing signs of trouble. The dry weather we’ve been experiencing this summer is giving us a window and we will try to take advantage of the low water conditions,” LaRue said.
Hawkins said despite knowing the draw down is necessary, the decision to renovate was a tough one.
“We know there are some quality northern pike in the lake and a few anglers have been taking advantage of this resource. But, if we wait too long to act, habitat and water quality will crash with many species of wildlife experiencing loss,” Hawkins said. “After restocking in 2018, fish growth will be extreme with northern pike growing up to 19 inches in the first year and yellow perch exceeding eight inches by the second growing season.”
Hawkins said he plans to add additional fish species to help control bullhead numbers.