Page 4 - Efficient Irrigation and Landscape Design Standards

Landscape irrigation is the single largest use of potable water in the United States. During summer months, outdoor water use creates peak demand on existing water supplies and system capacity. Water purveyors and utilities must increase supply to meet irrigation needs, sometimes as much as three to four times the amount used for domestic needs during the winter.
In Idaho, approximately two thirds of the total non-agricultural water withdrawn from the SVRP is devoted to landscape irrigation use. The population of Kootenai County living within the SVRP is projected to increase 81% by 2045. As it exists presently, water purveyors must petition the Idaho Department of Water Resources for additional water rights to serve their growing populations.
Forecasts show that water shortages will be occurring in the SVRP aquifer unless conservation measures are implemented or additional pumping capacity is added. Measures to conserve water should be implemented to lessen the burden on rate payers, otherwise rate increases will
be unavoidable in the future as water purveyors are required to install new infrastructure.
Daily Average Water Use In Spokane County (IN GALLONS)
Average summer consumption can increase to more than 350 million gallons per day in Spokane County.
Nationwide, landscape irrigation is estimated to account for nearly one-third of all residential water use, totaling nearly 9 billion gallons per day. As much
as 50 percent of water used for irrigation is wasted due to evaporation, wind, or runoff caused by inefficient irrigation methods and systems.
Sprinkler systems left unmaintained can cause runoff and damage hardscapes.
Locally, forecasts show water use increasing substantially by 2040 in the Spokane Valley-Rathdrum Prairie (SVRP) aquifer. Water demand in Spokane County is forecasted to increase 31% by 2040. The increase is approximately 156 CFS, which is significant given that the most recent USGS study indicates a close relationship between increases in aquifer withdrawal and decreases in Spokane River’s flow.
The public supply sector and self-supplied residential sectors are projected to increase by 41% and 47% respectively. During the same time frame population is projected to increase by 55% (based on the Washington State Office of Financial Management medium population projection for Spokane County).
4 IDAHO WASHINGTON AQUIFER COLLABORATIVE
“One way to combatwater shortages is to enact water effi cient irrigation and landscape requirements for new and
rehabilitated landscape projects.”