Outdoor water use is typically the first use to be curtailed during a drought declaration, with resultant plant stress or death and economic impacts to homeowners and businesses. Designing and building water conservation features into new development is a buffer against drought.
Compact, mixed-use developments with a small water footprint, drought tolerant landscaping, and reduced reliance on potable water for irrigation are more drought resilient than traditional development.
The impact of land-use planning on water conservation and drought mitigation has been shown in studies on lot size and water demand. A study of Utah households found that homes on 0.2 acre lots used half as much water as those on 0.5 acre lots, while Seattle households on .15 acre lots used 60% less than homes on 0.37 acre lots.
Developments that use less water put less strain on water systems, particularly during periods of drought when operators may struggle to deliver sufficient water as the resource dwindles and may have difficulty meeting peak demand during summer months. Higher levels of conservation/lower demand can relieve the necessity and costs of acquiring new water supplies, which are passed on to the taxpayer. Low water use development with drought-tolerant landscapes that require little supplemental water during the summer saves water utilities delivery, treatment, water acquisition, and energy costs and preserves limited water supplies.
Sterling Ranch is a 3,000-acre development that considers itself to be a 21st century community that is meeting customer demand for sustainable communities. The development is located south of Denver in Douglas County and was planned from the ground up to use water efficiently in order to address water supply problems within the County. Even so, it faced difficulty getting approval from the County, requiring a special agreement and demonstration period to prove that it would use less than the local zoning standard of over 244,000 gallons per unit per year. Instead, Sterling Ranch set a single-family water use target of 71,500 gallons of water a year per unit.
To meet the target, outdoor irrigated landscaped area is limited, requiring use of low water use plants, and efficient irrigation systems. Indoor water use is limited by the installation of water efficient appliances and fixtures. To ensure residents meet their target water use, each house has an individualized water budget with dual meters to separate indoor and outdoor water use. Billing rates for indoor and outdoor use are different, with a much more aggressive inclining block rate for outdoor use that is intended to discourage the customer from going over its budget. Customers can even opt to have the water provider manage their irrigation controls to make sure the budget is not exceeded.
To ensure water supply reliability, the development focuses on using water from different sources. In addition to groundwater and surface water, it estimates that rainwater will meet about 40% of the common area/playing field landscape demand, and that the development will achieve 100% water reuse.
Sterling Ranch has indicated that the lack of coordinated approval for land use and for water supply was a challenge, and that integrating the two by unifying the review process and improving inspection would be more efficient.
Developments like Sterling Ranch – ones that are built from the start with water conserving design, reuse and supply redundancy, and with mechanisms in place to ensure that efficiency standards will continue to be met – demonstrate that there are those in the development community that are prepared to invest in building drought resilient, sustainable communities.
Model Drought Resilient Community
Sterling Ranch is featured in the WRA report New House, New Paradigm
More information about Sterling Ranch can be viewed here.
The EPA hosts additional information, such as Green Infrastructure: Build Resiliency to Drought, which can be found here.
The American Society of Landscape Architects also features information on drought resilient design here.
Lastly, EcoBuilding – 11 Water-Conserving Projects and Products – can be viewed here.