Stroll around Fountain Lake and one will find signs of a thriving habitat of critters that call Fountain Park home. Willow Flycatchers weave their nests high in the park’s olive trees and Saguaro cactus are dotted with cavities dug by Gila Woodpeckers. At dusk, bats swoop and dart silently overhead, consuming pesky flies and mosquitoes while Egrets stand motionless at the water’s edge waiting for the perfect fish to snatch out of the water; fish that in a nearly 30-acre body of water, have a peculiar backstory.

According to Town of Fountain Hills Public Works Director Justin Weldy, the primary reason for aquatic life in Fountain Lake is that they are disposed of by those who purchased them for home aquariums.

“For Fountain Lake, with little to no exception, the majority of those fish are unwanted pets,” Weldy said. “They’re constantly restocked by people sneaking down there at night and dumping their aquariums.”

Since the lake changed from potable (drinking) water to reclaimed water, Weldy said he is not aware of any intentional fish stocking in the lake. Before the town was incorporated in 1989, however, fish were stocked to quell unwanted algae growth in Fountain Lake.

Pre-incorporated fish

Before serving as the Town’s former public works director for 12 years, Tom Ward worked for MCO Properties where one of his tasks was to reduce the algae that dispelled park visitors because of its odorous presence.

“We tried Tilapia,” Ward said, a commonly stocked tropical fish used to consume weed and filamentous algae. “The only problem was in the winter the fish would die because the water was so cold.”

When the lake was drained and relined in 2000, Ward said they pulled out some 2,500 Koi and 250 turtles. Most of the fish were given to the Koi Club who took them away in large tanks and the turtles were donated to local vets. A few Koi were transplanted to the pond at SunRidge Canyon Golf Club.

Around this time, the Town began treating the lake with algaecide, a practice that evolved from spraying chemicals from a small boat on the lake to a chemical drip system. The constant drip of chemicals proved to be too costly and environmentally poor and now, algaecide is applied only as needed.

“I started working at Fountain Lake as a graduate student,” Rick Amalfi said, vice president of Aquatic Consulting & Testing. Some 35 years ago, Amalfi was completing his Ph.D. in aquatic biology and chemistry at ASU. “The algae started to look like somebody dumped bright green paint in the water, especially along the north edge.”

Fish > chemicals

Spraying algaecide is a temporary fix for a perennial problem, Amalfi said. Its usage also has diminishing returns; if used too much, algaecide is deadly for fish that eat mosquitoes and midge larvae. Dying fish also means no lunch for the park’s bird population.

“There’s a natural predation with the fish and the waterfowl,” Amalfi said, who believes there are quite a few Carp in the lake. “You want some fish, especially bottom feeders to keep the down the midge population…but there is no fish that filters out planktonic algae. What you typically use fish for is weed management and large filamentous algae and Fountain Lake does not have either.”

“It’s a biological control rather than chemicals,” Lacey Schmitt said, a community fishing program specialist at the Arizona Game and Fish Department. “For weed control and vegetation control, the most common [fish] people stock are Tilapia and White Amur (grass carp).”

From his experience draining a 22-acre lake that held 22,000 fish, Amalfi thinks the current fish population in Fountain Lake may be north of that number.

Lake management

Over the past 25 years, the Town has invested substantially in proper lake management, including a 60mm bed liner to cut down on mossy green algae on the lake’s belly and a comprehensive aeration system that increases the levels of oxygen throughout the lake, reducing “dead zones” where algae would otherwise accumulate.

To this day, Amalfi sends a team to Fountain Park every week to test the lake’s nitrogen, phosphorus and oxygen levels to ensure air is circulating throughout the water column.

“Our main goals there are keeping the algae population reasonable so we don’t get accumulation downwind and unsightly conditions and no odors,” he said.

This regular maintenance also keeps the dreaded “fish kill” at bay, when fish pile up on the lake’s shoreline due to oxygen depletion, sustained high temperatures and rapid changes in air and water temperature.

Sturdy marine life

According to Justin Weldy, the salinity of the water in Fountain Lake is “staggering.” He also says the high turbidity of the water means the fish currently in the lake have overcome some obstacles.

Now retired, Ward works at SunRidge Canyon Golf Club in Fountain Hills. Occasionally, a brightly colored Koi fish will catch his eye in the pond near the clubhouse.

“It’s a circle that goes on with Mother Nature with those fish,” he said. “When I drive around on the golf course, I throw in a cracker.”