It's small, it's still and it's shallow. And right now, that recipe makes Lake LaVerne look gross.
A group of ISU faculty and students earned grant funds to launch "floating islands" water quality research in Lake LaVerne.
A 2.8-acre pond constructed in 1916, the lake has turned green with an algae bloom. Chris Strawhacker, landscape architect in facilities planning and management, said the filamentous algae showed up earlier this year, thanks to warm and dry spring weather.
"We noticed the algae earlier this year, just as the ice was going out at the end of March," Strawhacker said. "That's about four to six weeks earlier than normal."
The nutrients that feed the algae come from sources like animal waste and the decaying algae itself. The shallow depths of the lake -- only about six feet at its deepest -- allow the sunlight to penetrate and warm the calm waters for quick and plentiful algae growth.
Although it's not a threat to the lake and its wildlife, the algae is unsightly. FPM has taken steps to sustainably manage its growth by:
- Eliminating fertilizer use on surrounding grass and runoff areas
- Applying aluminate sulfate (alum) that binds to the phosphorus and starves the algae
- Diluting the water with well water and rain water collected off Music Hall
- Aerating the water to increase oxygen levels
- Working with the ISU Limnology Lab to monitor water quality
- Managing wildlife, such as discouraging nesting geese
FP&M crews and student volunteers have used nets and rakes to pull algae from the lake surface this spring. Strawhacker said the alum treatment timeline was moved up because of the early algae bloom, and results should be visible soon.
"With some help from the weather, it should begin to look better as students end the spring semester and graduate," Strawhacker said.
Lake LaVerne's appearance is not uncommon in the Midwest, but the visibility of the popular campus landmark gets people talking about it. FPM's move toward more environmentally friendly management methods have improved the lake's health, but long-term solutions -- such as increased water depths -- are costly.
"We're exploring other ways that we can manage the lake -- from increasing the amount of water flowing into the lake, to removing the nutrient rich sediment and reshaping the bottom for deeper water," Strawhacker said.