Trout On Display

An aquarium inside an Idaho treatment plant demonstrates the life-giving quality of the facility’s Class A reuse effluent.
Trout On Display
The original rainbow trout caught in the neighborhood pond maneuver past the decorative ornaments to feed in the 120-gallon aquarium.

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The wastewater treatment plant in Ketchum, Idaho, treats 1.25 mgd, largely for reuse in irrigation. One of the plant’s most popular features, though, holds just 120 gallons of water. It’s an aquarium, fed by plant effluent, that nurtures rainbow trout.

The plant team installed the aquarium as a test to demonstrate that the trout could live in a subdivision pond supplied by flow-through effluent. It has become a focal point for visitors of all ages during plant tours

Aesthetic Features

The Ketchum/Sun Valley Wastewater Treatment Plant sits at the foot of Bald Mountain, a popular destination for skiers and visitors to the Sun Valley Ski and Golf Resort. It is surrounded by subdivisions and neighborhoods with large, expensive homes.

One such neighborhood, Weyyakin Ranch, features a half-acre pond stocked with rainbow trout. The pond is part of more than two miles of streams and smaller ponds that the subdivision developer promotes as an aesthetic feature.

The ponds and streams are used for irrigation. Until summer 2012 they were fed with water from Trail Creek, a tributary to the Big Wood River, site of the treatment plant’s outfall. To meet the city’s goals to reduce plant discharges and to acquire water rights associated with Trail Creek, and to satisfy the subdivision’s desire to reduce its water costs, the two parties struck an agreement by which the plant pumps 0.5 mgd of reuse water to the half-acre storage pond.

“Their main purpose was to have enough water to support a decorative pond filled with rainbow trout for aesthetic purposes and irrigation,” says Mick Mummert, lead operator of the 7.0 mgd (design) activated sludge, extended aeration plant, jointly owned by the City of Ketchum and Sun Valley Water and Sewer District.  

Needing Proof

But subdivision residents were concerned whether the trout could survive in the effluent, says Jeff Leamon, plant operator. So, to demonstrate the effluent’s suitability, Leamon led the installation of a 120-gallon flow-through aquarium in the plant’s UV disinfection building. The team put in half a dozen trout caught in the Weyyakin Ranch pond by Teri Pierce, plant lab technician. “I just took my fly rod over there one day and stocked the aquarium with some nice-sized trout,” says Pierce.

The fish survived with no problem, and today trout thrive in the neighborhood pond, says Leamon. Since the test trout were returned to the pond, the aquarium has been restocked with fingerlings provided by the aquaculture department of the College of Southern Idaho (CSI). Flow is maintained at 120 gallons a day to simulate the water turnover in the subdivision’s 0.5 mgd holding pond. As demand for reuse water increases, flow through the aquarium will increase proportionately. “Once a month I clean the tank gravel and wipe down the glass,” Leamon says. “It takes about an hour, and that’s it for maintenance.”

Trout Care

Pierce monitors the aquarium water temperature and feeds the trout daily with commercial fish pellets recommended by CSI. “Because they metabolize protein more slowly in cold temperatures, I feed them smaller amounts during the cold months,” says Pierce. “They are a lot like the goldfish I have in my pond at home.”

The aquarium is a highlight of tours conducted for grade school and middle school kids, college students and other visitors. Mummert says the aquarium shows off the quality of the reuse water because the supply to the aquarium is drawn just downstream from the disinfection step and is the same effluent that goes to the outfall.

The plant is permitted by the state to distribute more than 3 mgd of recycled water for irrigation and snowmaking. Other neighborhoods are interested in connecting to the reuse water infrastructure. Treatment plant co-owner Sun Valley Water and Sewer District has already installed a 1-million-gallon storage tank and pumping facility to use effluent for water features and golf course irrigation at the Sun Valley Resort in 2014.
Says Leamon, “Sometime in the future they might use ‘snowffluent’ for snowmaking on the slopes.”   



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