Page 18 - Efficient Irrigation and Landscape Design Standards

5.2 WATER BUDGET ALLOWANCE (continued)
Irrigation schedules should provide parameters for the irrigation controller to be applied during the following:
• The plant establishment period.
• The established landscape.
• Temporarily irrigated areas.
The local jurisdiction should also require the following information to be submitted within an irrigation schedule:
• Irrigation interval (days between irrigation).
• Irrigation run times (hours or minutes per irrigation event to avoid runoff ).
• Number of cycle starts required for each irrigation event to avoid runoff.
• Amount of applied water scheduled to be adjusted on a monthly basis.
• Application rate settings for:
» root depth » plant type
» soil type
» slope factor
» shade factor
» irrigation uniformity or
efficiency

Irrigation Water Budgets and Schedules satisfying the following conditions must be submitted as part of the Irrigation and Landscape Documentation Package:
1. A water budget analysis based on one of the following calculation methods:
» Appendix B - Landscape Water Budget. Landscape Irrigation Best Management Practices. The Irrigation Association and American Society of Irrigation Consultants, May 2014.
» WaterSense Water Budget Tool. United States Environmental Protection Agency.
» Landscape water features shall not use potable water unless the water feature recirculates water used in its operation.
» The irrigation water use may be monitored by the water purveyor after the date of release of the performance bond.
» Alternative water sources such as recycled wastewater or rainwater are encouraged as permitted by the Department of Ecology. Such water sources shall not be subject to the limits of the water budget.
2. An annual irrigation program with monthly irrigation schedules, are required for:
» The plant establishment period. » The established landscape.
» Any temporarily irrigated areas.
» A schedule for weaning water requirement plants from
irrigation.
3. The irrigation schedule must:
» »
» »
Be included on the Irrigation Design Plan as well as in the Irrigation and Landscape Documentation Package.
Include run time (in minutes per cycle), number of cycles per day, frequency of irrigation for each station (weekly/monthly) and maximum operating hours per day for peak demand.
Program valves for multiple repeat cycles shall be required where necessary to reduce runoff, particularly on slopes and soils with slow infiltration rates.
Provide the amount of applied water (in hundred cubic feet, gallons, or in whatever billing units the local water supplier uses) recommended on a monthly and annual basis.
4. Whenever possible, irrigation scheduling will incorporate the use of evapotranspiration data such as those from the AgriMet weather stations to apply the appropriate levels of water for different climates.
5. Sprinkler irrigation will be scheduled between the hours of 7 p.m. - 10 a.m. to avoid irrigating during times of high temperature. Avoid irrigating during winds greater than 20 mph. Both practices will reduce losses due to evaporation.
18 IDAHO WASHINGTON AQUIFER COLLABORATIVE