Turfgrass Water Conservation Alliance (TWCA) created the Irrigation Calculator (based on this calculator from Pennington) to help end-users predict the runtimes of their irrigation systems. Simple.
TWCA collaborated with a network of public and private researchers including Oregon State University, University of Washington, University of Arkansas, and NexGen Plant Science Center, on a series of multi-year inquiries to answer some basic questions about site specific conditions.
The Irrigation Calculator is simple. Click the greenness of your grass (fun fact: during development we called this the "lush level"). Know the irrigation rate and weekly frequency. Remember where you live. It's true, there are some curveballs in there; not everyone knows if they have TWCA Qualified turfgrasses, but generally, pretty spoon and June.
The calculator itself is an example of interdisciplinary cooperation on a public/private partnership resulting in an immediately useful tool.
Jack Karlin is the Program Administrator for TWCA. His interest is in using policy and the built environment to create livable and sustainable communities.