CREJ

20 / BUILDING DIALOGUE / December 2021 T he growth of cities in the American West has in- creased water consump- tion from the Colorado River and pushed this critical natural resource beyond its limits. Yet we could re- duce some of this demand within the communities that we design and build by switching to a style of land- scaping that is more appropriate for our region, thereby conserving wa- ter while restoring some of our state’s unique biodiversity. Here in Colorado, where we typically get 12 to 15 inches of precipitation per year, the average person uses 150 gal- lons of water per day. Sixty percent of residential water usage goes to support landscaping. This amounts to approximately 90 gallons of water per person per day used to keep exotic landscapes on life support. When we look at wild landscapes in the fall, the changing colors reveal patterns that may be im- perceptible at other times of the year. These pat- terns in the landscape provide subtle clues to the ways that plants are arranged in nature, based on available soil moisture. In planning restoration projects, ecologists look at the aspect (the direction the site faces and the amount of sunlight it receives) as well as the de- gree of slopes, variations in soil moisture, and oth- er conditions of the site. This same information is also valuable when planning sustainable land- scaping projects utilizing native plants with min- imal watering or maintenance costs. The grounds that surround buildings receive different amounts of stormwater, sunlight, exposure to wind, and other influences than undeveloped open spaces. To create a low-water use garden, it is necessary to evaluate the site in these terms and put the right plant in the right place for our purposes. In 2007–2008, McWhinney (the developer of Cen- terra, a master planned community in Loveland), High Plains Environmental Center, Ark Ecological Services and BHA Landscape Design created a doc- ument called the “Centerra Stormwater Pond and Natural Areas Design Guidelines.” The guidelines won a Land Stewardship Award from the American Society of Landscape Architects in 2009. Although this document is primar- ily about the design and construction of native open space, it has influenced our thinking on all aspects of landscape de- sign. In front of our visitor center at HPEC is a bioswale. It is a low channel that receives the stormwater runoff from our parking lot. The channel has a series of pools that are excavated to different depths. Each shallow pool contains plants with vary- ing degrees of moisture requirements. The channel banks have plants that require increasingly less moisture up to the top of the bank, which receives virtually no moisture except our natural precipitation. This type of swale also can improve water quality by removing nutrients from fer- Jim Tolstrup Executive Direc- tor, High Plains Environmental Center Restoring Nature Sustainable Landscapes Can Reduce Costs, Conserve Resources Snowmelt from the mountain peaks of Colorado provides water to over 40 million people in 14 Western states. The arrangement of plants in nature gives us subtle clues about the moisture content and soil type of a site. When we know where plants want to be, we can design landscapes that require little or no water because they are in the correct place to support them.