District expects water budgets to produce savings
The Santa Clara (Calif.) Valley Water District (SCVWD) is developing a Web-based water budgeting tool to assist large water customers in cutting their water use for landscape irrigation. Incorporating digital imagery and mapping technologies, the budgeting process will allow customers to compare actual water use to recommended use.
SCVWD is a water wholesaler for Santa Clara County, which encompasses more than 900 square miles and more than 1.5 million customers. The district’s large landscape sites — schools, recreation facilities, homeowner associations, parks, and industrial and retail complexes — use an estimated 100,000 acre feet of water per year for landscape irrigation.
Much of that water is used unnecessarily, according to Jerry De La Piedra, water conservation specialist for SCVWD. “So many people over-water. The potential for conserving water and saving money is substantial,” he notes.
As a signatory to the Sacramento-based California Urban Water Conservation Council (a statewide consortium of urban water agencies, public interest organizations and private entities organized to promote efficient water use), SCVWD is implementing Best Management Practices, including large landscape audits and water budgets. “It’s supposed to be done at the retail level, but we’ve decided to go ahead and implement the BMPs, pretty much all of them, on behalf of our retailers,” De La Piedra says.
SCVWD determined that, as part of the budget development process, it would have to map large landscapes throughout the county. Ruling out the time-consuming and costly option of mapping the sites manually, the district implemented a pilot study, assessing the affordability of using digital imagery to create site profiles.
The district contracted with Thornton, Colo.-based Space Imaging to compile satellite imagery for a 12-square-mile project site in Mountain View. The company gathered the images and, using computer-based analysis, classified them according to land cover (e.g., turf, plants, trees, shrubs, non-irrigated pavement). Combining that data with a digital parcel map of the city, the company produced measurements of the various vegetation types within each parcel.
“We estimate that there are about 50,000 large landscape meters [in the county], which means there are probably over 30,000 large landscape sites,” De La Piedra says. “We wanted to see how accurate [the data] was and whether it was something we could do on a bigger scale.”
Ground checking showed that the Mountain View data was more than 90 percent accurate, prompting SCVWD to move forward with aerial imaging for its countywide budgeting plan. “For as big as we are, it becomes cost-effective,” De La Piedra notes. “It is a method of getting the images all at once.”
Obtaining a $400,000 grant from the California Department of Water Resources, the district hired the same contractor it had used in Mountain View to produce multispectral images of the entire county. The company conducted flyovers in June 2002 (gathering data from an airplane was quicker than gathering it from a satellite), and it will deliver the data to SCVWD by May. The district will combine the landscape mapping data with weather data to create the recommended water budgets for its customers.
SCVWD is investing $230,000 in in-kind services (i.e., staff time for checking data, developing a budgeting database and managing the mapping contract) for the project. Already, De La Piedra has developed the software that will drive the online budgeting tool.
The Web-based application will be available to users on the SCVWD Web site (http://www.valleywater.org) by the end of next year. At that time, users can visit the site, enter information identifying their parcels, enter their meter readings and view the current status of their water use. “They’ll have a graph and a table at the end showing them if they’re over budget, under budget or close to budget,” De La Piedra explains.
Adhering to recommended budgets is entirely voluntary, but SCVWD is confident that the budget tool will encourage customers to conserve water. “Most people don’t realize how much water they’re using, and, if we can show them that they’re using twice as much water as they really need, that’s one way to get them to use less water,” De La Piedra notes. “Also, we have an audit program in which we actually send a person to a site, turn on the irrigation system and go over [conservation measures]. If they are over budget, they can sign up for that program, and we can get someone to their site to show them what needs to be changed.”
SCVWD expects initial water savings of 15 percent for sites that use the online budget tool. With participation in its audit program, the district anticipates that the percentage will grow.