Earlier editions: 2026-09
Division 8 — Planning and Development›Chapter 1.1 — Zoning (Coastal)
Ventura County Municipal Code Appendix L5 Examples for Calculating the Water Budget
Ventura County Municipal Code · 2026-10 edition · updated 2026-10-04 · Ventura County
Cite as: Ventura County Municipal Code APPENDIX L5 · Text as of 2026-10-04
Example 1:
A hypothetical residential landscape project in Ventura, California, with an irrigated landscape area of 1,000 square feet; no special landscape area (SLA = 0).
[Figure]
Hydrozone: Label each planting area polygon with a number or letter.
Plant Water Use Types: Identify water demand for each hydrozone.
Plant Factor1 : [13] Plant factor range shall be as follows:
•
Low water use plants: 0.1 to 0.3
•
Moderate water use plants: 0.4 to 0.6
•
High water use plants: 0.7 to 1.0
| Hydrozone | Plant Water Use Type(s) | Plant Factor (PF)* | Irrigation Method | Irrigation Efficiency | ETAF (PF/IE) | Hydrozone Area (HA) (square feet) | ETAF × Area | Estimated Total Water Use (ETWU) |
|---|---|---|---|---|---|---|---|---|
| 1 | High | 0.8 | Drip | 0.81 | 0.67 | 100 | 67 | 1807 |
| 2 | High | 0.7 | Drip | 0.81 | 0.86 | 100 | 86 | 2319 |
| 3 | Medium | 0.5 | Drip | 0.81 | 0.61 | 100 | 61 | 1645 |
| 4 | Low | 0.3 | Drip | 0.81 | 0.37 | 350 | 130 | 3506 |
| 5 | Low | 0.2 | Drip | 0.81 | 0.24 | 350 | 84 | 2265 |
| 1,000 (A) | 428 (B) | 11,542 |
Maximum Applied Water Allowance (MAWA)
MAWA = (ETo) (0.62) [(ETAF × LA) + ((1-ETAF) × SLA)]
Average ETWU = 0.55
MAWA = (43.5) × (0.62) [(0.55 × 1,000 sf) + ((0.45 × 0)]
MAWA = (43.5) × (0.62)[(550) + (0)]
MAWA = (26.97) × [550]
MAWA = 14,834 gallons
To convert from gallons per year to hundred-cubic-feet per year:
= 14,834/748
(100 cubic feet = 748 gallons)
= 19.83 hundred-cubic-feet per year
Estimated Total Water Use (ETWU) (gallons per year)
ETWU = ETo × 0.62 × ETAF × Area
HA #1: (43.5) × (0.62) × (0.67) × (100) [26.97] × [67] = 1,807
HA #2: (43.5) × (0.62) × (0.87) × (100) [26.97] × [87] = 2,346
HA #3: (43.5) × (0.62) × (0.61) × (100) [26.97] × [61] = 1,645
HA #4: (43.5) × (0.62) × (0.37) × (350) [26.97] × [130] = 3,506
HA #5: (43.5) × (0.62) × (0.24) × (350) [26.97] × [84] = 2,265
ETWU = 11,569 gallons per year
Compare ETWU with MAWA.
MAWA = 14,834 gallons per year
ETWU = 11,569 gallons per year
♦
The ETWU (11,569 gallons per year) is less than MAWA (14,834 gallons per year).
In this example, the water budget complies with the MAWA.
(Ord. No. 4492, § 9, 6-21-2016)
Footnotes:
--- (13) ---
Plant Factors are derived from the Department of Water Resources 2000 publication "Water Use Classification of Landscape Species."
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