The following are excerpts from the Landscape Water Conservation Guidelines compiled by the Green Industry Council, San Francisco Bay Area Region, of which John Blevens is committee chairman.

The Green Industry Council is an active coalition of landscape architects, contractors, growers, irrigation consultants and specialists, retailers, distibutors and gardeners, including representatives from all professional associations in Northern California’s green industry.

The following is not the total publication, but represents the main body of guidelines. It is the council’s objective to work with management professionals, municipalities, counties, the public and within the industry to preserve precious water resources, support efforts to improve water management and assist in developing water conservation plans that are equitable and prevent undue hardships.

Although these guidelines provide a methodology to accomplish landscape water conservation, the Green Industry Council endorses a water distribution program that provides economic incentives for implementing these guidelines and an educational process for improving water management. A well-planned program that meets the needs of consumers, while rewarding water savers and penalizing water wasters, is essential.

These guidelines are intended to be used by developers, landscape architects, contractors and homeowners in designing landscaping for new developments, renovations to existing residential and commercial landscaping, and for city planning departments for use in reviewing applications for permits.

The key to water conservation in landscape is good management of a well-designed irrigation system. The city or county should provide incentives for water users to conserve water in the landscape all the time, not just during periods of water rationing . Examples of incentives include increased allocations for users who develop and implement the results of a water audit; pricing structures that penalize heavy water users; and financial incentives to improve the efficiency of an existing irrigation system.

All new landscaping and rehabilitated landscaping are recommended to be designed and maintained in accordance with these landscape water conservation guidelines. When possible, all attempts should be made to encourage water retention on the site and allow infiltration of rainwater into the soil and groundwater table. In order to meet these guidelines, basic elements should be incorporated into the planting and irrigation plans.

The planting plan should show:

1. All landscaping that is to be removed.
2. Location, type and size of all existing and proposed plants, including turf.
3. Calculations showing the total planting area, turf planting, hardscape and water area, expressed as a percentage of the total landscaped area. The landscaped area is defined as the parcel less the building pad, driveway and parking areas.

4. That hillsides exceeding 2 to 1 slope incorporate terracing where possible.
5. Plants are selected that are best suited to the regional climate and that are drought resistant.
6. Water-intensive landscape elements are confined to areas of high visibility or areas of high use and grouped together, enabling separate irrigation.
7. Turf is used in a practical manner for high use or aesthetically desirable areas. When turf is used, drought resistant varieties should be considered. Turf should not be used on slopes in excess of a 4 to 1 ratio.
8. Planting schemes are compatible with irrigation requirements so that overhead spray systems will not be necessary in areas resulting in excessive overspray.
9. Bottom of slopes are not within two feet of adjacent hardscape (patios, walks, etc.).
10. Soil treatment: soils for planted areas should be amended with a minimum of two inches of organic material incorporated into the top eight inches of soil unless otherwise recommended by a soil report. A minimum of two inches of organic mulch should be added to planted areas to reduce evaporation, moderate soil temperatures and discourage weeds. Sheet plastic or other nonporous materials should not be placed under the mulch.
11. Pool cover specified if applicable.

Irrigation plans should include:

1. Location, type and size of all irrigation components, including water meter or specifications of pump and/or other sources.

2. Minimum static water pressure of point of connection.
3. Gallons per minute and precipitation rates for each valve circuit.
4. Irrigation schedules reflecting the amount of water needed to maintain adequate plant health and growth, based on actual water needs and climate data for the area. Irrigation watering schedules including run times and frequency for each valve circuit should include a schedule for the establishment of new plant material and length of establishment and a schedule for the maintenance of plant material after established.
5. A multi-program controller capable of multiple cycles.
6. Separate valved sections installed, based on water use of plantings and exposures.
7. All sprinkler heads should have matched precipitation rates within each control valve circuit.
8. Pop-up sprinklers in turf areas should have a pop-up of at least four inches.
9. All sprinkler heads having a check valve installed when necessary to prevent low head drainage.
10. Sprinkler head spacing placed at a maximum of 50% of the diameter of throw (head to head).
11. Individual heads (bubblers or drip) in isolated areas and plantings eliminating watering of bare ground.
12. Sprinkler layout should be done so that water overspray is minimized.
13. Overhead sprinkler systems should not be used where excessive overspray will occur.
14. Drip or bubbler irrigation systems for trees (regardless if planted alone or in groundcover or turf areas).
15. Sprinkler heads with a precipitation rate of .85 inches per hour or less on slopes exceeding a 4 to 1 ratio.
16. No overhead irrigation systems used on slopes exceeding a 2 to 1 ratio.
17. Design of drip irrigation appropriately reflecting long-term system and maintenance requirements.

Irrigation operation:

1. Irrigation controller schedules should be set to water between sunset and sunrise.
2. Utilize watering cycles when programming irrigation controllers. Water should be applied at a rate that matches the soil absorption rates, Use multiple cycles to permit several short duration waterings that will allow water to soak into the soil rather than run off. For repeat cycles of watering, a minimum of one hour should pass prior to applying additional water. Following these guidelines will increase landscape irrigation efficiency and will be an important step in implementing landscape water conservation.

Landscape Drought Action Plan. During a drought, additional measures may be required beyond long-term water conservation practices.

In the case of drought:

1. Determine quantity of water available or water allocation for landscape irrigation.
2. Determine watering schedule, based on plant requirements that reflect soil and climate data.
3. Total water requirements from step two and compare to water availability determined in step one.
4. If requirements exceed availability, reduce watering times to 70% of original schedules. This 70% level is generally one that will stress plants but allow survival. Additionally, there may be native or other drought resistant plantings that can survive without any irrigation.
5. If requirements still exceed availability, determine planting areas not to receive irrigation. Use a priority rating that considers the importance of the area’s functional use, the importance of aesthetic contribution and the cost to rehabilitate the area after the drought has passed.

Additional plant tips: During stress periods of turf, application of pre-emergent herbicides on turf can greatly reduce annual weed infections. These materials are most effective when applied before weed germination is expected, usually during February and March. Deep water large, established trees and shrubs at the sign of moisture stress, indicated by yellowing interior leaves or wilting that does not recover in evening or when plant is shaded or when new growth wilts.

John Blevens has been an irrigation consultant in Northern California for more than 15 years and is a principle of the I.S.C. Group, Inc. John has been involved in landscape projects ranging from small residential gardens to large projects involving specially computerized control and monitoring systems. John presently is the president of the American Society of Irrigation Consultants, serving on the board of directors for the Northern California Turfgrass Council and on the Committee for Water Policy Consensus. Call him @ 415-4719244