**StreamStats in New Jersey**

StreamStats for New Jersey can be used to estimate instantaneous flood discharges with exceedance probabilities of 0.5, 0.2, 0.1, 0.04, 0.02, 0.01, and 0.002 for ungaged, unregulated or slightly regulated, non-tidal streams in New Jersey. These exceedance probabilities correspond to recurrence intervals of 2-, 5-, 10-, 25-, 50-, 100-, and 500-years, respectively. StreamStats for New Jersey also can be used to estimate monthly flow-duration and monthly low-flow frequency statistics for ungaged streams in Coastal Plain and non-coastal regions of New Jersey for baseline and current land- and water-use conditions. The equations were developed to estimate 87 different streamflow statistics, which include the monthly 99-, 90-, 85-, 75-, 50-, and 25-percentile flow-durations of the minimum 1-day daily flow; the August–September 99-, 90-, and 75-percentile minimum 1-day daily flow; and the monthly 7-day, 10-year (M7D10Y) low-flow frequency. The reports below present the regression equations used to estimate the noted streamflow statistics, describe the errors associated with the estimates, and describe the methods used to develop the equations and to measure the basin characteristics used in the equations. Users should familiarize themselves with the reports before using StreamStats to obtain estimates of streamflow statistics for gaged and ungaged sites.

- Watson, K.M., and Schopp, R.D., 2009, Methodology for estimation of flood magnitude and frequency for New Jersey streams: U.S. Geological Survey Scientific Investigations Report 2009-5167
- Watson, K.M., and McHugh, A.R., 2014, Regional regression equations for the estimation of selected monthly low-flow duration and frequency statistics at ungaged sites on streams in New Jersey: U.S. Geological Survey Scientific Investigations Report 2014–5004, 59 p.

**Click on this link **to obtain general information on the New Jersey application, as well as specific sources and computation methods for basin characteristics.** **

**NOTE 1****:** Although 1990 population density was used for the development of the regression equations in SIR 2009-5167, the New Jersey StreamStats application uses the more current 2000 population-density data.

**NOTE 2****:** Watson and McHugh (2014) provide two sets of regression equations for flow duration and low-flow frequency statistics, intended to reflect conditions for a “base” and a “current” period. The “base” period is defined as the years a streamgage had little to no change in development and water use. The “current” period is defined as the 1989–2008 water years (Oct. 1, 1988 to Sept. 30, 2008). The base period of record is representative of a period when the basin was unaffected by change in development. The current period is representative of more recent increased development.

StreamStats for New Jersey was developed in cooperation the New Jersey Department of Environmental Protection and the U.S. Army Corps of Engineers.