What is WUCOLS?

Answer: WUCOLS stands for Water Use Classifications of Landscape Species. It is a University of California Cooperative Extension Publication. The project was developed by the San Francisco and San Mateo County Office in cooperation with 32 landscape professionals. This project was initiated and funded by DWR. The purpose and intended use is to provide guidance to landscape professionals when selecting plant material, while taking into consideration water needs. It also serves as a guide to assist in developing irrigation schedules for existing landscapes. A Guide to Estimating Irrigation Water Needs of Landscape Plantings in California

Which water laws affect landscape water use in California?

Answer: The California Constitution (Article X, Section 2) and the Water Code (Sections 100 & 101) prohibit "waste or unreasonable use" of water.

Is there a specific law governing the landscape water in California?

Answer: Yes. Assembly Bill 325 required all local jurisdictions to adopt a landscape water conservation ordinance by 1993. DWR's Model Water Efficient Landscape Ordinance reflects the State policy of promoting the conservation and efficient use of water in landscape.

What are the objectives of DWR's Water Efficient Landscape Ordinance?

Answer: The objectives, consistent with AB 235 are:

• To promote the values and benefits of landscapes while recognizing the need to invest water and other resources as efficiently as possible.
• To establish a structure for designing, installing and maintaining water efficient landscapes in new projects.
• To establish provisions for water management practices and wastewater prevention for established landscapes.

How can I get help with landscape water use calculations when submitting a landscape project to the city or county?

Answer: DWR's Model Water Efficient Landscape Ordinance has examples of specific calculations, including:

• Calculation of the Maximum Applied Water Allowance (MAWA)
• Calculation of the Estimated Applied Water Use
• Calculation of the estimated Total Water Use

Where can I get information to calculate the Maximum Applied Water Allowance (MAWA)?

Answer: MAWA calculation requires using DWR's CIMIS Reference Evapotranspiration (ETo) in inches per year. CIMIS ETo data is available for many locations in California.

Or for any special request you can call, (800) 922-4647, Monday through Friday from 8 AM to 5 PM.

What does CIMIS ETo mean?

Answer: CIMIS stands for California Irrigation Management Information System. ETo stands for reference evapotranspiration. ETo is an estimate of the amount of water used by water evaporated from both the soil and the amount used by well-irrigated grass (transpiration). It is calculated based on weather data measured on site, at DWR's CIMIS weather station and retrieved daily by a central computer in Sacramento.

I'm in landscaping and I need CIMIS ETo information. What is the cost of obtaining it?

Answer: The CIMIS information is free. Access the CIMIS webpage at wwwcimis.water.ca.gov

What are landscape coefficients?

Answer: Landscape coefficients are a reasonable approach to determine how much water is used by a landscape planting in relation to CIMIS ETo. The landscape coefficient method is explained in A Guide to Estimating Irrigation Water Needs of Landscape Plantings in California, The Landscape Coefficient Method and WUCOLS III.

Should I rely solely on CIMIS ETo data, landscape coefficients, and the available water holding capacity of soils to schedule my irrigations?

Answer: No. Irrigation scheduling will rely heavily on the experience of the person responsible for the landscape design and/or maintenance. It also relies on estimates for water use, such as CIMIS ETo data, as well as soil moisture monitoring devices (rainfall sensors), which all contribute to accurate and efficient irrigation scheduling.

How many acres of irrigated landscape do we have in California?

Answer: We are working very hard in cooperation with local agencies to find a good answer to this question. Approximations can be made based on past surveys of land use by counties conducted in different years by DWR, which have values for urban acres. Assuming that the growth in urban acres correlates to the trend in increased county populations, we can come up with conservation ratios between landscape and urban acres. By 1995, the range of landscape acres was between 1.2 and 1.4 million acres, including mainly urban irrigated landscape.

My client would like a long term comparison between a high water use landscape project, (including large turf areas and high water-use plants) and a landscape project using limited amounts of water (based on recreational needs and lower water-use plants). What technical and economical parameters should I consider for my analysis?

Answer: Assume that both projects would provide the same long term recreational, aesthetic and economical benefits to the client. A study during the lifetime of two similar landscape projects concluded the following:

• Both operational and maintenance costs (such as energy, water, fertilizers, pesticides, labor, fuel etc.) represented over 80% of the total cost, while the design and construction represented less than 20%.
• Both annual operational and maintenance costs were less than half in the low water-use landscape project compared to the higher water-use landscape project.
• The money saved each year as net savings in operational/maintenance costs in the low water-use landscape project generated financial cost savings.

How can I attend a landscape water audit class?

Answer: DWR is no longer directly sponsoring landscape water audit classes. However, the Irrigation Training and Research Center (ITRC) is still providing this type of training for a fee in different California Regions. To find out the current schedule please call Cal Poly, San Luis Obispo, at ITRC (805) 756-2434.

Has the California Building Standards Commission approved the revised California Graywater Standards?

Answer: Yes, on March 18, 1997. The most significant change in the standardsthat graywater systems can now be used in commercial, industrial, single-family, and multi-family projects. DWR retains copies of the revised Standards which are available upon request. Click here to view the Graywater Standards in PDF format.

Is there information available regarding the use of gray water for residential landscape in California?

Answer: Yes. DWR has a publication called Using Graywater in your Home Landscape - Graywater Guide.

Where can I find technical information about the use of recycled water for landscape purposes in California?

Answer: Please visit the Recycling and Desalination Web Page.