The question is not simply watering your lawn but how often and how much water you provide. The NDSU Extension Service Yard and Garden Report at http://www.ag.ndsu.edu/yardandgardenreport/documents/2014-08-04/summer-lawn-care explains:
"Lawns need 1 to 1 1/2 inches of water per week, either from you or Mother Nature. Water deeply. It’s better to give your lawn a big drink of water rather than a series of sips.
"Roots grow where the water is. If you water deeply, you will develop a deep root system. If you only sprinkle the surface of the soil, you will create a shallow root system."
If you have additional or specific questions, contact Todd Weinmann, Cass County Extension horticulturist at 241-575707 or email@example.com.