# Flow Statistics for Pennsylvania Streams

Streamflow statistics can be determined using StreamStats for Pennsylvania for ungaged streams in Pennsylvania that are minimally altered by regulation or diversions. The following statistics can be determined on StreamStats: peak flows (50, 20, 10, 2, 1, and 0.2 percent annual exceedance flood), low flows (7-day, 10-year; 7-day, 2-year; 30-day, 10- year; 30-day, 2-year; and the 90-day, 10-year low flows), base flows (10- year, 25-year, and 50-year base flows), and mean flows (mean annual flow, harmonic mean flow). The reports below document the regression equations available in StreamStats for Pennsylvania and the errors associated with the estimates obtained from the equations.

- Roland, M.A., and Stuckey, M.H., 2008, Regression equations for estimating flood flows at selected recurrence intervals for ungaged streams in Pennsylvania: U.S. Geological Survey Scientific Investigations Report 2008-5102, 57 p.
- Stuckey, M.H., 2006, Low-flow, base-flow, and mean-flow regression equations for Pennsylvania streams: .U.S. Geological Survey Scientific Investigations Report 2006-5130, 84 p.

Streamflow statistics for streamgages can also be found using StreamStats for Pennsylvania or in published USGS reports (see links below). For guidance on techniques regarding weighting and transference of statistics, see USGS SIR 2008-5102 or USGS WRIR 00-4189.

#### For most current streamflow statistics at streamgages (unregulated and regulated) in Pennsylvania:

- USGS OFR 2011-1070
- Peak-Flow Statistics: table 4
- Low-Flow Statistics: table 2
- Base-Flow Statistics: table 3
- Mean-Flow Statistics: table 5
- Flow-Duration Statistics: table 5

The USGS-PA Low-Flow Statistics web application has been superseded by USGS 2011-1070, table 2, and the USGS StreamStats web application.