by Glen Dake, FASLA
Western states face new struggles to match water use with water supply. Landscape architects are finding a wide range of regulations and incentives to drive landscape water use down and support a growing population.
The 2019 Colorado River Drought Contingency Plan committed each of the Colorado Basin states to reduce the amount of water they take from the Colorado River during drought conditions. The junior water rights holder, Arizona, committed to a 7% reduction in annual water use starting in 2020. That state is home to the second-fastest growing city in the U.S., with a 56.6% increase in population since the last census: Buckeye, AZ. This is one of several dynamics that are impacting water policies in the Colorado Basin states: Arizona, California, Colorado, Nevada, New Mexico, Wyoming, and Utah.
To reduce water use states are turning to the remaining area of conservation potential: water that is consumed in urban landscapes. In past years, urban water use per capita was reduced through promotion of low-flow bathroom fixtures and water-wise clothes washers that have been replacing old models. A sampling of many approaches that Western cities and counties are applying to meet their water conservation goals follows.
Westminster, Colorado conducts post-occupancy inspections. John Berggren of Western Resource Advocates, a non-profit promoting clean air and water throughout the western U.S., says that the City periodically inspects landscapes to ensure that what was shown on the approved site plan still exists. The City has a site plan inspector who manages the process. Alterations to water efficient landscaping are treated as code violations, enforceable like any other code violation.
Pima County, Arizona has adopted seven zoning districts with no setback required between the unit and the lot line. In the zero-lot-line pattern permitted in these districts, yard space, and outdoor water use, can be minimal provided that the County’s other building code requirements are met. (See Western Resource Advocates’ “Integrating Water Efficiency Into Land Use Planning in the Interior West: A Guidebook for Local Planners” for more information.)
Los Angeles, California, served by its municipal water utility, Los Angeles Department of Water & Power, will pay $3 per square foot to support a project replacing turf with drip irrigation, a stormwater infiltration structure, and well-mulched shrubs. The regional water wholesale agency, the Metropolitan Water District of Southern California, shares the costs of this rebate. For the MWD’s planning purposes, each square foot of turf replaced saves $44 per year in terms of water they need not obtain and distribute (MWD board letter 7-3 12/5/97 and updates). In the period July 2018 to February 2020, turf removed throughout MWD’s service area totaled 4.43 million square feet.
San José, California is served by five water providers. The City adopted water conservation targets in its Green Vision Plan and reviews progress annually. Their water conservation goal is to reduce citywide per capita water consumption by 25% from 2010 to 2040. In the past six years, water use is down 22%. In San José all building projects of 10,000 square feet or more are required to achieve LEED Silver certification; to achieve this certification, landscape architects design irrigation and plantings to apply water sparingly.