Instead of inmate beds, a bed of lettuce sits in the Denver jail’s Palmer Building, where a convict dormitory was transformed into a space for sustainable food growth.

In February, officers at the jail undertook a pilot program to begin growing their own food on a small scale through aquaponics after hearing about similar setups nationwide, said jail Deputy Hazel Pablo. The Smith Road facility is waiting on a $20,000 grant through Denver’s Department of Environmental Health to expand the operation.

An aquaponics system combines fish with plant cultivation, said J.D. Sawyer, president of Colorado Aquaponics. The fish are raised on site, and their nutrient-rich waste is pumped into water housing plant roots. The roots take in the nutrients and return clean water to the fish tank, Sawyer said.

“It’s really meant to be a balanced ecosystem, very similar to what happens already in a natural environment. It has the benefit of localized food production,” Sawyer said.

The result: organic, pesticide-free vegetables produced in a sustainable fashion, Pablo said.

If the jail were to receive the grant and expand the system, the city could save $20,000 in food costs a year, city officials said. Mayor Michael Hancock praised the effort as “a great example of how our city departments are working to make their operations more sustainable.”

Jail authorities approached Colorado Aquaponics to conduct a feasibility study about two years ago to determine whether an aquaponics system would be a good fit for the facility, Sawyer said.

When experts gave the OK, the jail decided to start small.

Colorado Aquaponics installed a $4,000 aquaponics system in the Palmer Building with the intent of training officers to maintain the system and, eventually, training inmates to do the same.

“A project like this will help with inmates’ re-entry back to the community,” Pablo said. “There are a lot of jobs in green fields, so we would be training them in applicable skills. We would be teaching them how the whole system works.”

Pablo said it would probably take 10 inmates to tend to the aquaponics system.

The 7,000-square-foot Palmer Building is empty aside from a small bed of greens — romaine and chard — and a barrel of fish.

“Step back,” Pablo said as she sprinkled a high-protein fish food into the tank and more than 30 tilapia rushed to the top, splashing water out of the sides of the tank.

Deputy Jeff Bush and Pablo are the main caretakers of the aquaponics system, although both said it was fairly self-sustaining.

Pablo said it took about 60 days for the water in the filtration system to grow enough good bacteria to add fish, and the seedlings were installed soon after.

It took about two months for the vegetable seedlings to become the vibrant, green blooms they are now.

The officers trade off feeding the fish daily, harvesting the greens every couple of weeks, cleaning the fish tank and adding about 10 gallons of new water to the system every two weeks.

“The system is so sustainable,” Pablo said. “Aquaponics saves about 70 (percent) to 90 percent of water normally used to garden because the filtration cycle reuses the water,” Pablo said.

Fish food and the occasional chemical are the only maintenance costs, officers said.

After the fish were fed, Pablo pulled the thriving romaine out of its bed and placed it into a container bound for the kitchen in the officers’ mess hall.

“That lettuce will be in the dining hall tomorrow,” Bush said.

Peppers will be grown next, Pablo said, and officers are requesting more greens every day.

The small-scale system produces only enough vegetables to feed officers at the moment, but the jail wants to expand the system with funding.

Officers hope to grow a variety of vegetables that will feed the 800 to 1,000 inmates at the Denver jail, around 1,500 inmates at the downtown facility and the estimated 700 officers.

“The ultimate goal would be to fill this entire building, pop the roof off so we could use the sun instead of lights and incorporate the inmates,” Pablo said.

The Larimer County Corrections center has a similar food-growing program that uses inmates to tend to a garden where its produce is later sold at a community farmer’s market.

Tim Hand, community corrections director at the corrections center, said he “takes his hat off” to the Denver jail for doing this initiative.

“There’s a lot of therapeutic analogies that play into managing a vegetable garden and managing your own life. If you take care of it, nurture it, good fruits will grow, so to speak,” Hand said.

He said the garden has made a noticeable, positive impact among inmates at the corrections center.

“One of the things that everybody in corrections understands is that you want to keep people motivated and doing productive things that they can be proud of,” Hand said.

The jail will find out about the grant Oct.28.

“We really want to see this happen,” Sawyer said. “It’s a very powerful project to be involved with. To potentially create a model for sustainable food productions at a jail is very intriguing to us. Plus, it’s close to home, so we definitely want to see it through.”

Elizabeth Hernandez: 303-954-1223, ehernandez@denverpost.com or twitter.com/literally_lizzy