New regression equations were made available state-wide in Arizona on June 15, 2017 in StreamStats beta version 4. The new equations can be used for estimating the 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual peak-flow exceedance probabilities (2-, 5-, 10, 25-, 50-, 100-, 200-, and 500-year recurrence intervals, respectively), and also the 1-, 3-, 7-, 15-, and 30-day flood-duration flows at the same exceedance probabilities for user-selected ungaged sites. Version 3 is no longer available for Arizona, as a unique method for computing contributing drainage areas for user-selected sites in Arizona sometimes causes delineated basins to appear incorrectly in the version 3 interface. The new equations are from the following reports: