Town of Avon requires proposed landscape designs to not exceed 7.5 gallons of water per square foot of area per season ^* (Gal/Sf/Season) allocation.

The Water Efficient Landscape Design Budget Calculation is rooted in the formula:
Total Landscape Area / Water Needed to Support Landscaping.

In order to determine the Water Needed to Support Landscaping, all areas within any landscaping plans are assigned one of the following Hydrozone Water Use Categories:

1.

No Water

2.

Very Low

3.

Low

4.

Medium

5.

High

6.

Cool Season / Turf Grass

7.

Water Feature

Each Hydrozone Category represents an estimated Water Allocation needed to support its flora (See Table 1:1). Very Low, Low, Medium, and High Hydrozone categories also contain the potential to be Drip Irrigated or Spray Irrigated (Drip being less water-intensive than Spray).

Table 1:1 - Water Allocation per 1000 sq ft per season by Hydrozone Type

The calculation requires the replacement of these numbers with the square footages of the hydrozones being proposed. Please see calculation examples for clarification.

^*  Season can be approximated as the period of time between the average date of the last killing frost in the spring to the average date of the first killing frost in the fall.

WATER EFFICIENT LANDSCAPE DESIGN BUDGET CALCULATION EXAMPLES

Using these inputs relative to the size of each hydrozone in a single landscape plan, a person can assess the estimated water use for the entire landscaping plan. The following scenarios showcase the variety of landscaping plans possible, their estimated water use, and potential for approval under the 7.5 gallon per sf. per season limit.

Scenario One: A landscape plan that is equally split between areas that require no water, and turf grass areas:

Takeaways:

• This plan's water budget is exactly the maximum potential water allocated.

• Any landscaping plan that exceeds 50% turf grass will likely not be approved

Scenario Two: A drip-irrigated landscape plan that is equally split between Low, Medium, and High

Takeaways:

• This plan's water budget is below the maximum potential water allocated.

• Scenario Two is less water-intensive than Scenario One, despite 50% of the landscaping in Scenario One not requiring any water.

• 3000 sq ft of equally mixed Low, Medium, and High hydrozones is less water-intensive that 1,500 sq ft of grass

Scenario Three: A drip-irrigated landscape plan that is equally split between Low and High hydrozones

Takeaways:

• This plan's water budget is below the maximum potential water allocated.

• Scenario Three is less water-intensive than Scenario Two

• A medium water hydrozone does not represent the median between the low and high hydrozones

Scenario Four: A spray-irrigated landscape plan that is equally split between Low and High hydrozones

Takeaways:

• This plan's water budget is above the maximum potential water allocated.

• Scenario Four is more water-intensive than Scenario Three, despite the hydrozone area sizes remaining the same in both

• Spray irrigation is more water-intensive than drip irrigation, and could be the difference between approval / denial of a landscaping plan

Scenario Five: An equal mix of drip irrigated, Very Low and Low hydrozones, and Turf Grass

Takeaways:

• Very Low and Low hydrozones can be adequate off-sets for turf grass area

Scenario Six: An equal mix of all hydrozones AND an additional water feature

Takeaways:

•  Equally mixed hydrozones have the potential for approval, even when water-intensive water features are included.

•  A 1,000 sq ft water feature would exceed the 7.5-gallon allocation