The orchids, baobab tree and other plants in the tropics building of the Minnesota Zoo require about 8,000 gallons of water to maintain their lush rain forest look. And that’s just for the plants. In one building. For one week. There’s no way around it — running a zoo is a water-hungry business.

But a grant awarded last week will allow the zoo to use rain to supplement the millions of gallons of water its plants, animals and visitors require, and reduce runoff into lakes and streams.

The Apple Valley zoo is among dozens of zoos across the country examining water use and trying to cut back. In St. Paul, Como Park Zoo and Conservatory opened a garden this summer that draws from a pool of rainwater for irrigation.

“Zoos today think of themselves as conservation organizations,” said Rob Vernon, spokesman for the Association of Zoos & Aquariums, and they spend more time promoting that message. “People now have an expectation that that is what their local zoo is doing.”

The association surveyed members last year and found 40 of the 91 zoos that responded are in the midst of water reuse or rainwater harvesting projects, Vernon said. That surge is, in part, a result of green technology becoming less expensive, he said.

Changes at the Minnesota Zoo will be covered by $500,000 in funding from the Metropolitan Council and local watershed and conservation organizations. That will pay for several projects over the next two years.

When it rains, much of the water that lands on the roof of the Minnesota Zoo’s tropics building, which covers about an acre of land, flows into the green-colored Main Lake in the center of the zoo.

Officials want to channel it into massive cisterns instead, and use it for other purposes — to irrigate those thirsty tropical plants or as toilet water. Zoo officials expect it will lower their water bills, but they’re not certain how much.

The zoo could gather up to 35,000 gallons of water from one inch of rain, said Derik Otten, the zoo’s director of project services.

Collecting runoff would help Main Lake, which has “a bit of a algae problem,” Otten said. The grants will also fund a study of ways to reduce nutrients and bacteria in the lake.

Additionally, the zoo plans to remove pavement in some areas to prevent runoff and create two bioretention ponds. The ponds will cut down on water running into storm sewers that lead to waterways and lakes. They will be built along a new greenway trail planned at the zoo entrance and the path to the baby farm animal exhibit.

Signs will explain the additions to visitors, Otten said.

“If we can teach them about rain gardens and bioretention ponds, the better off we are,” he said.

Raising awareness of water problems and solutions is a critical piece of the project, said Travis Thiel, a specialist with the Vermillion River Watershed Joint Powers Organization, which is putting $100,000 toward the zoo projects.

“I don’t think that nearly enough people know about these issues and what they can do about it, or we would have clean water in the state,” Thiel said.

For watershed and city officials, the changes are important because they could result in water quality improvements outside the zoo, too.

When Main Lake floods, water containing phosphorus and animal feces can end up in wetlands on zoo property and eventually in nearby Alimagnet, Farquar and Long lakes, Thiel said.

“The zoo is an interesting case,” Thiel said, because of its massive pastures and animals. “Dealing with water issues is even more difficult there.”

Wide-reaching impact

In animal exhibits, water usage quickly adds up.

Como Park Zoo changes out 8,000 gallons of water from its bear pools four times a week, zookeeper Blake Ericksen said. That’s all sterilized and reused, he said.

“Water is expensive,” he said. “It’s much better to recycle it.”

That philosophy has extended to Como’s conservatory. Centennial Garden, which opened in June, was designed to use rainwater. Water collected from the visitor center roof ends up in a 280,000 gallon cistern underground that is hooked up to the irrigation system, horticulture manager Tina Dombrowski said.

It’s an idea they want to use in future projects, she said.

“We will look more closely at recycling and reusing our water,” Dombrowski said. “It started with the Centennial Garden. There are going to be more.”

While an underground cistern or bioretention ponds may not be particularly splashy projects, they could have wide-reaching influence. Successful projects that save money and help the environment could be replicated elsewhere, said Vernon, of the Association of Zoos and Aquariums.

“What’s happening at Como Park, what’s happening at Minnesota Zoo … will impact the rest of the community,” he said.