How to Hydrozone a Planting Plan


Many planting plans we receive at Atomic Irrigation are incorrectly hydrozoned. AB 1881 states that all planting plans must be grouped by similar watering requirements based on plant type, irrigation method, sun exposure, soil type, slope or other criteria.

As you can probably imagine, planting plans not hydrozoned properly make it nearly impossible to create an efficient irrigation plan.

Below is a properly designed planting plan clouded by hydrozone with a corresponding hydrozone table with all the pertinent information needed.

Hydrozone Plan

Plan courtesy of City of Santa Monica, Office of Sustainability and Environment

Why is this plan properly hydrozoned?

Because this plan shows plants grouped by watering requirements and sun exposure. The corresponding table (shown below) displays hydrozone name, area, percent of total area, plant water requirements, hydrozone description and sun exposure.

From this, anyone reviewing the planting plan and table, can easily see it is hydrozoned properly. Even an irrigation designer.



Hydrozone Sq Ft % of
Total Area
A 91 2 LVL Native Grass/Shrub Sun all day
B 444 11 LVL Medium-Low Water Shrub Sun all day
C 263 7 LVL Large-Low Water Shrub Sun all day
D 173 4 LVL Medium-Low Water Shrub Part Shade
E 3 LVL Native Tree Part Shade
F 3 H Mixed Roses Sun all day
G 14 H Warm Season Turf  Sun all day
H 8 M Medium Shrub Part Sun
J 3 M Large Shrub Sun all day
K 3 M Medium Shrub Part Shade
L 2 M Flowering Tree  Sun all day
M 6 M Mixed Citrus Tree Sun all day
LVL=Low-Very Low, M=Medium, H=High

Atomic Irrigation is an irrigation design firm that produces irrigation construction documents, water resource management plans and consults to various landscape architecture, architecture, engineering firms and cities and municipalities in California.


Don’t be, we got it covered.


Atomic Irrigation
1158 26th St., #241
Santa Monica, CA 90403