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Adventure Africa Phase II
Dohmen Family Foundation Hippo Haven

Fact Sheet


Summer 2020


Adjacent to the Red River Hog Habitat


The Milwaukee County Zoo has completed the construction of Adventure Africa Phase II, the Dohmen Family Foundation Hippo Haven. Adventure Africa is the largest physical change to the layout since the Zoo officially opened in 1961, transforming 25 percent of the Zoo’s current footprint. The first phase of the project, the elephant and mixed species habitat, opened in May 2019.

The newly constructed exhibit is home to the Zoo’s two hippos—39-year-old male, Happy, and 50-year-old female, Patti. (Average life expectancy for a hippo living in a zoo  is 37.4 years.)

Exhibit Elements:

The exhibit allows visitors an up-close experience with the resident hippos, while the animals benefit from a larger and cleaner habitat, due to a state-of-the-art filtration system, along with even more opportunities to make their own choices. Choice is an important part of animal enrichment, with the goal of the animals displaying their natural behaviors.

Perhaps the most exciting aspect of Hippo Haven is the underwater viewing tank. MCZ is one of only 12 zoos in the U.S. to offer visitors this viewing option of hippos. The viewing tank is similar to the polar bear and harbor seals’ underwater habitat.

The new 3,500-square-foot beach area, a combination of torpedo and mason sand, gives the hippos the choice of where they’d prefer to lie. The area also features anchored logs for enrichment. Although wild hippos spend most of their days in the water, they do come onto land to bask and feed. The beach area resembles a similar space as to where hippos would be found in their wild habitat.

Because hippos spend approximately 16 hours a day underwater, occasionally it was difficult for visitors to see the animals in the former hippo habitat. At times, only a glimpse of the top of the hippos’ heads or a portion of their rumps may have been visible. The new underwater viewing tank provides visitors a better opportunity to see more of the hippos and their behaviors.

The new pool design is more than three times the size of the former hippo outdoor watering hole. The tank itself holds 60,000 gallons of water, with varying depths and surfaces throughout, reaching up to 7 feet at the deepest. Sloped rocks and ramps are incorporated as resting options for the animals.

The new watering hole better simulates their natural habitat, as hippos often push off objects to move through the water.

In order to give all guests a clear view of the animals, much detail and careful thought was put into the filtration system to be used for the outdoor pool. It was decided to construct a similar system using ozone that was installed in the Zoo’s Otter Passage exhibit, which opened in 2018.

The massive system uses ozone to purify and clarify the water. Specifically, it uses five standard sand filters and pumps, and the hippos’ system has a custom-made piece of equipment to separate their feces, as hippos defecate in the water. The waste collected by the filtration system will be composted. This system is also used in the indoor hippo pool.

Not only will this new filtration system offer a healthier environment for the hippos, it will also save approximately 20 million gallons of water annually. In the former exhibit, zookeepers had to empty the pools at the end of each day. The new exhibit will filter and reuse the same water for the entire season.

Habitat Amenities:
  • 60,000-gallon pool with varying depths and surfaces; for a maximum depth of 7 feet
  • Sloped rocks and ramps in the pool for resting options; two entrances into the pool
  • Beach area includes a variety of surfaces and anchored logs for enrichment
  • Massive filtration system to keep water clean for the hippos and clear for visitors
  • Water is filtered through the system three times every hour
  • Each glass panel of the pool is approximately 3-inches thick
  • Entire pool glass dimensions:  85-feet in length; 7-feet in height
  • Keeper platform above the pool has water cannon for enrichment

Educational Zones:

  • “Splatter Zone” – simulates a hippo spraying its poop
  • “Open Wide” – shows the unique characteristics of a hippo’s mouth
  • “Bloat” – educates visitors about a hippo bloat
  • Hippo Skull –a real encased skull with interesting facts
MCZ Hippos:

Happy: Male; birthdate Jan. 1, 1981; arrived in 2009 from the National Zoo in Washington D.C.
Approximate weight:  5,300 pounds

Patti: Female; estimated birthdate in 1970; arrived in 1972 from the Dallas Zoo in Dallas, Texas
Approximate weight: 3,000 pounds         

Project History:

2008: Representatives from Mortenson Construction, a Milwaukee-based construction and design firm, and MCZ staff tour zoos, visiting underwater hippo exhibits in San Diego, San Antonio,
St. Louis, Tampa Bay and Orlando

2009: The Zoo expands its indoor hippo area; planning begins for a future outdoor hippo habitat

2013: New Zoo Master Plan is initiated; commitment made to keep African elephants

2015: HGA Architects and Engineers and PJA Architects & Landscape is hired for Adventure Africa: Phase I Elephant Exhibit design. Cost of Wisconsin to construct all exhibit rockwork

2016:  Demolition begins for new Elephant Exhibit

May 4, 2019: Adventure Africa Phase I opens; new elephant and mixed species habitat

July 2019: Demolition begins for new Hippo Exhibit

Adventure Africa
Phase I: Elephant and Mixed Species Exhibit:

$17 million; funding from Milwaukee County and Zoological Society of Milwaukee

Adventure Africa
Phase II: Hippo Exhibit:

The $13.5 million Hippo Haven project was made possible with donations from the Zoological Society of Milwaukee, and from Milwaukee County on behalf of the Milwaukee County Zoo.

Adventure Africa
Phase III:
Rhino Exhibit; includes areas of remaining pachyderm facilities and current rhino/tapir exhibits; demolition tentatively scheduled to begin in 2022
Hippos in the Wild:
  • Hippos are native to sub-Saharan Africa
  • They live in areas with abundant water, spending up to 16 hours per day underwater to stay cool
  • Hippos are not endangered; their current International Union for Conservation of Nature (IUCN) status is listed as vulnerable to extinction
  • The IUCN estimates that only 125,000 and 148,000 hippos remain in the wild
  • Their biggest threats are poaching and habitat loss