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Monthly Irrigation Budgets

The City of Santa Barbara calculates and assigns a monthly irrigation budget to all dedicated irrigation meter accounts. The monthly irrigation budget is based on daily weather data, the type of plants, and total size of the irrigated area. Any water use within the calculated irrigation budget is charged at Tier 1 rates, and any water use in excess of the budget is charged at Tier 2 rates. Please see our water rates webpage for current rates.

How are the Monthly Irrigation Budgets Calculated?

The purpose of providing a monthly irrigation budget is to bill based on the water needs of your landscaping and current weather conditions. Each account has a different budget based on the type of plants and size of irrigated area, and the budget will vary monthly based on changes in weather.

Monthly irrigation budgets are based on the daily weather data, the type of plants, and the total size of the irrigated area.  

 

Monthly Irrigation Budget Tier 1 = (ETo)(.62/748)((PF x IR)/IE))

  • ETo = Reference evapotranspiration data from a local weather station (as inches)
  • 0.62/748 = Conversion factor (inches to hundred cubic feet of water)
  • PF = Plant factor - a research-based coefficient that reflects the amount of water different plants need, 0.8 is used for turfgrass and 0.3 is used for all other plants (shrubs).
  • IR = Irrigated area - square footage of irrigated area(s), by plant type (turfgrass or shrubs)
  • IE = Irrigation efficiency (80%). Since an irrigation system cannot perfectly deliver the amount of water that plants need, this part of the equation assumes that the irrigation system is only 80% efficient, an industry standard.

It is the input of the ETo data that causes the monthly irrigation budget to fluctuate.  All other parameters will stay the same, unless changes are made to landscaping and reported to the City. See section near the bottom of the page about expanding your irrigated area. 

ETo Data

Evapotranspiration (ETo) is the loss of water to the atmosphere by the combined processes of evaporation (from soil and plant surfaces) and transpiration (from plant tissues). It is an indicator of how much water your shrubs, lawn, and trees need for healthy growth and productivity. ETo is measured by a combination of solar radiation level, wind speed, humidity, and temperature. The City uses daily ETo data from a weather station located at the Santa Barbara Municipal Golf Course. 

To obtain ETo data to determine your water budget, sign up for a free CIMIS account here.

How Am I Billed?

No matter what your water budget is, you are only billed for the water you use. If your usage is below the monthly irrigation budget, all use will be billed at your Tier 1 rate. However, if your usage exceeds the monthly irrigation budget, all use in excess of the budget is billed at the Tier 2 rate.

Water Budget Formula Parameters

Tier 1

Tier 2

IR

(Irrigated Area)

PF

(Plant Factor)

IE

(Irrigation Efficiency)

Water use within budget (per HCF)

Water use exceeding budget
(per HCF)

Irrigation - Agriculture

$3.31

$25.41

Crop

75%

80%

Irrigation - Recreation

$5.22

$25.41

Turf

80%

80%

Shrubs

30%

Irrigation - Urban (Residential/Commercial)

$13.77

$25.89

Turf *

80%

80%

Shrubs

30%

* Maximum irrigated areas apply for turfgrass on irrigation accounts, as follows:

  • Residential turfgrass area cannot exceed 20% of total irrigated area
    • If measurements are greater than 20% of total, the remainder square footage will be assigned to the irrigated shrub area.
  • Commercial turf area = 0% of total irrigated area
    • If irrigated turf area exists, it will be assigned to the Irrigated Shrub Area.
  • Plant Factor % allotments reflect the requirements of City’s Landscape Design Standards, SBMC 22.80.

How is My Irrigated Area Determined?

Your landscape’s assigned irrigation budget is based on City measurement records of your irrigated area. If this amount seems inaccurate, call (805) 564-5460 to schedule a groundtruthing of your site’s irrigated area. The City will also be selecting sites for groundtruthing if it appears the City’s current records are inaccurate. Your account may be subject to mandatory groundtruthing measurement to verify the accuracy of measured irrigated area and plant types.

What if I Change/Expand My Landscape

The total irrigated area measurement is an important part of your monthly irrigation budget calculation. If you change or expand your landscaped area please contact the City at (805) 564-5460. City Staff will discuss the landscape changes with you and either schedule a new groundtruthing appointment or review approved landscaping plans (if applicable) to determine the new irrigated area measurements.

How Do I Determine How Much to Irrigate to Stay Within My Irrigation Budget?

In order to properly manage the irrigation water on your site to stay within your irrigation budget, you are encouraged to use the resources below. These will help you determine how to water your landscaping efficiently each month:

- Get a free water checkup to review your sprinkler timer schedule and how to schedule for efficiency.
- Use the Watering Calculator and Weekly Watering % Adjust.
- Upgrade your sprinkler timer to a Smart Irrigation Controller 
- Encourage your landscaper to manage your landscape to a budget. Two tools landscaper can use: 
        - CLCA Certified Water Management Program online reporting. (If your landscaper is not certified, send them through the training or hire one that has.)
        - Sign up for our online Landscape Budgets Program by contacting us for a username and password to get started.

Last Updated: Aug 31, 2021
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