Welcome to the Washoe Evapotranspiration Website

Your actual watering needs may vary according to water pressure, applied gallons per minute, nozzle size, coverage, soil type and slope of the land.

The 85% efficiency is the result from using a crop coefficient in the equation. The crop coefficients are used with Evapo-transpiration to estimate specific crop evapotranspiration rates. The crop coefficient is multiplied by the Evapotranspiration value to arrive at a crop ET (ETc) estimate. The resulting ETc can be used to help schedule when an irrigation should occur and how much water should be put back into the soil.

When setting your timer at the suggested "run-time," use short but frequent watering cycles for best results. For example, if your sprinkler type indicates watering for 20 minutes, split-up the run-time into two to four increments, ie., two at 10 minutes or four at 5 minutes if possible, allowing at least one hour between watering. This allows the water to soak deep into the soil and prevents run-off.

Calculate your runtime

inches per day
Runtime result minutes per day

How is this calculated?

What are my watering days?

   No watering, gives our water system a chance to recharge

Tuesday, Thursday and Saturday
   Even Addresses

Wednesday, Friday and Sunday
   Odd Addresses

Shut down your sprinklers between 12 p.m. and 6 p.m.

Memorial Day through Labor Day

What is Washoe EvapoTranspiration and how does it pertain to me and my yard?

The Washoe E.T. website has been developed to help you water less and still have an attractive lawn. This site will show you how to use just the right amount of water to replace moisture that has been lost from the soil and grass.

The Washoe E.T. project is a network of weather stations located in the Reno-Sparks, NV region that monitor evapo-transpiration rates. These rates can then be used as a tool to estimate lawn and crop watering needs.

The EvapoTranspiration, or E.T. for short, is a method of lawn watering that help Nevadans save our most precious resource - water. E.T. also helps improve water quality. By watering less, you avoid runoff. Overwatering causes more water to run off than soak in. This runoff could carry pollutants from the gutter into our water supply.

The less waste we create, the better.

Some extra useful information:
To see a map of the weather station sites, click here

Information regarding applying proper watering and lawn care - click here

Gross estimated runtimes for small to medium turf - click here

Printable Washoe E.T. brochure, click here (spread the word)

TMWA holds free irrigation workshops each year to assist customers with system start up, setting controllers for Weather - Wise Watering. Please email conservation@tmwa.com to RSVP for an upcoming workshop, or for more information about watering- click here.