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Throughout the complex, transitions — between exhibit areas, between nature and structure, and between land and water — flow naturally, as the Sacramento River once did.

Reusing Space and Materials

The need for sustainable design was evident in the Turtle Bay mission statement, which emphasized stewardship of the region, says Ray Calabro, AIA, an associate with Bohlin Cywinski Jackson and project manager for the Turtle Bay project.

"We felt that the building should evoke the mission statement by presenting methods of sustainable construction," Calabro says. "They wanted to use the building as an exhibit, so that visitors could understand why the building was made. We utilized the sustainable building elements in such a way that it would be very evident."

Park visitors come first to the Turtle Bay Visitor Center, which opens to a tranquil, tree-shaded boardwalk that leads to the main museum. Although visitors may not realize it, the location of these two buildings is the first indication of the complex's sustainability. The design team was careful to situate the structures on already disturbed land to minimize impacts on the surrounding landscape.

"The museum was sited at the north end of an existing boardwalk at a natural clearing near the river," Calabro says. "The western part of the site had already been disturbed for a previous project. But the eastern side was situated in the 100-year floodplain, so we lifted it up on concrete piers to minimize the site disturbance."

Within its 34,000 square feet (3200 square meters), the museum houses five permanent and two changing exhibits and has an annual capacity of 350,000 visitors. Designed to bring the outdoors in, the museum contains wood columns and 22-foot (6.7-meter) steel-restrained glass walls.

One wall features water sheeting down past Native American petroglyphs etched in the glass. Columns resemble native trees visible just outside, and large roof overhangs provide shade for visitors, reducing the structure's reliance on electrical cooling systems.

Waste products are used throughout the building. The concrete used for the floor slabs contains 15 to 25 percent fly ash, a waste material from coal-burning power plants. Carpet, tiles, glass, and building insulation are all made of recycled materials.

Countertops at the visitor center and museum cafe were made with a material from Phenix Biocomposites made of recycled newspapers and soy resin. Rice straw, usually considered a waste product and burned, was used to build a wall in the visitor center.

Although architects interested in sustainable design have been incorporating such materials for years, the materials are not always visible in completed projects. In the Turtle Bay Museum, the design team made a point to expose a portion of the straw bale construction as an educational tool.

The materials offer other benefits as well. "By using rice straw as a building element, it can be recycled into a very good insulation material," Calabro says. "At 22 inches (56 centimeters) wide, it forms a very thick wall. It keeps the interior cool in the summer and warm in the winter."

Making the River and Wetlands Visible

Visibility is the unifying theme of the Turtle Bay structures and exhibits. In the literal sense, visitors can view the exposed straw bale construction or the surrounding landscape through the glass walls. In the museum lobby, the roots of an oak tree replica can be seen branching out below a glass floor.

"One of the elements of the visitor center was we wanted to make it transparent, so you had a psychological way of seeing through to the wetlands beyond," Calabro says.

The museum also aims to make the region's environmental pressures visible. After descending through a simulated limestone cave that echoes the region's geology, visitors enter "The Visible River" exhibit. There, a 12 by 24-foot (3.7 by 7.3-meter) window exposes a 22,000-gallon (83,000-liter) aquarium containing aquatic life of the Sacramento River.

Native fish such as trout, steelhead, and sturgeon swim amid tree snags and boulders. A massive cottonwood tree appears to have fallen into the water, protruding from the aquarium into the visitor space, where it hangs from the ceiling. This snag gives visitors another visual connection to the river's teeming life.

More explicit is the museum's "From the Land, From the Water" exhibit, which provides a chronological journey of resource management in the region, from prehistoric hunting and gathering to 20th-century ranching and mining.

"Redding's success has been built on nature giving to people," says Judy Lalouche, president of Turtle Bay. "Now we turn our concentration to how people can give back to nature."

The last stop for many visitors is the terrace cafe, which offers a view of the Sundial Bridge, still under construction. It is a fitting symbol for the Turtle Bay complex, bridging the divide that too often exists between buildings and the natural world.

Kim A. O'Connell is a freelance writer who specializes in environmental and preservation journalism.

The boardwalk and museum at the Turtle Bay Exploration Park in Redding California, by Bohlin Cywinski Jackson. Photo: Kurt Hoffmann In the Turtle Bay Museum lobby, the roots of an oak tree replica can be seen branching out below a glass floor. Photo: Harvey Spector The architects made a "window" to display the straw-bale wall construction. Photo: Karl A. Backus A pedestrian bridge, designed by Santiago Calatrava, will be completed in 2004. Image: Santiago Calatrava Aerial view of the Turtle Bay Exploration Park. Photo: Turtle Bay Exploration Park Site plan of the Turtle Bay Exploration Park, with the museum to the north and the visitor center to the south. Image: Bohlin Cywinski Jackson The visitor center, like the museum, was built on previously developed land, to minimize disturbance of the natural landscape. Photo: Karl A. Backus Gift shop at the Turtle Bay Visitor Center. Photo: Karl A. Backus   Click on thumbnail images to view full-size pictures.