New regression equations were made available state-wide in Arizona 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:

• Paretti, N.V., Kennedy, J.R., Turney, L.A., and Veilleux, A.G., Methods for estimating magnitude and frequency of floods in Arizona, developed with unregulated and rural peak-flow data through water year 2010: U.S. Geological Survey Scientific Investigations Report 2014-5211, 55 p.
• Kennedy, J.R., Paretti, N.V., and Veilleux, A.G., 2014, Methods for estimating magnitude and frequency of 1-, 3-, 7-, 15-, and 30-day flood-duration flows in Arizona: U.S. Geological Survey Scientific Investigations Report 2014–5109, 35 p.