Orestimba Creek Hydrology - Stanislaus County

TABLE 5BOrestimba Creek near NewmanFlow Duration10-Day through 30-Day10-DAY 15-DAY 20-DAY 30-DAYWY Date Day-cfs Date Day-cfs Date Day-cfs Date Day-cfs1993 1/13/1993 552.1 1/13/1993 397.1 1/7/1993 319.1 1/13/1993 250.61994 2/15/1994 0.6 2/10/1994 0.4 2/5/1994 0.3 1/26/1994 0.21995 3/9/1995 749.6 3/10/1995 646.4 3/9/1995 519.7 3/9/1995 365.91996 2/19/1996 453.3 2/19/1996 335.1 2/4/1996 317.5 1/31/1996 274.81997 1/21/1997 790.3 1/20/1997 547.1 1/20/1997 423.6 1/1/1997 443.61998 2/2/1998 1404.3 2/2/1998 1073.0 2/2/1998 950.0 2/1/1998 776.61999 2/7/1999 65.7 1/31/1999 47.9 1/27/1999 40.2 1/27/1999 29.72000 2/14/2000 210.6 2/12/2000 205.5 2/12/2000 173.6 2/12/2000 128.02001 2/24/2001 114.3 2/24/2001 98.4 2/23/2001 76.4 2/12/2001 52.42002 12/29/2001 90.8 12/29/2001 63.1 12/21/2001 50.5 12/21/2001 34.72003 12/16/2002 212.2 12/16/2002 158.0 12/16/2002 135.3 12/16/2002 98.22004 2/25/2004 146.7 2/19/2004 103.6 2/18/2004 79.6 2/18/2004 53.92005 2/15/2005 351.0 2/15/2005 260.3 2/15/2005 213.4 2/15/2005 152.92006 4/1/2006 200.2 4/1/2006 146.9 3/26/2006 117.3 3/15/2006 94.12007 10/1/2006 0.0 10/1/2006 0.0 10/1/2006 0.0 10/1/2006 0.0Salado Creek above I-5The Salado Creek above I-5 flow frequency curve was computed by multiplying the Del Puertoflows by 34 percent. This factor is the ratio of the Salado drainage area to the Del Puerto drainagearea (24.6/72.6 = 0.34). This same method and ratio are consistent with the original hydrologyemployed at Salado in the West Stanislaus County 2001 feasibility study. The statistical methodsand options used here are the same used for the above Del Puerto Creek analysis. Table 6 showsthree iterations of Salado Creek above I-5 statistics. This table lists peak, 1-, 3-, 5-, 7-, 10-, 15-, 20-,and 30-day frequency statistics. The first are the results of the statistics without a low outlier test.The second are the results considering only the lowest water year as a low outlier. The third and finalset of FAA runs uses the low outlier cutoff option to exclude the two lowest flow years of each ofthe durations and sets the skew to -0.5 for each curve. Note that the removed flows were 1 or 2 cfs orless. As with Del Puerto Creek, these flows should not drive the standard deviations or skews of thecurves that determine the upper end of the frequency curves. Chart 5 plots the means and standarddeviations of each set. It omits the 20-day curve and data. Table 7 tabulates the peak and volumedata for the period of record. The dates are not included.This analysis completes the update of the flow frequency curves found in the 2001 Feasibility Study,West Stanislaus County, California, and Hydrology Appendix for the Sacramento District USACE.Although not needed for this report, Salado Creek’s frequency curves were updated to complete theset of the three frequency curves presented in the 2001 feasibility study. Chart 5 displays the SaladoCreek above I-5 peak and flow duration frequency curves.Flood hydrographs are discussed following Table 7.18