Revision History for USGS Scientific Investigations Report 2010–5205 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009 ----------------------------------------------------- First posted October 2010 ----------------------------------------------------- Description of Changes to November 2011 Revision Page vi, in the table of contents caption for figure 22, the text “Median annual and” was deleted from the beginning of that caption. Page 1, right column, first full paragraph, text “Results of a Mann-Whitney statistical test indicate that the median annual discharge is not significantly different between the periods 1970–79 and 1989–2008. Monthly medians for the two periods, however, indicate a shift in the pattern of runoff from snowmelt to monsoon-dominated flow” was replaced with “Results of the Mann-Whitney test indicate that the median annual discharge was not significantly different between the periods 1970–79 and 1989–2008, but median monthly discharges were significantly less for 7 of 12 months from 1989 to 2008 as compared to 1970–79.” Page 47, right column, last paragraph, beginning with the second sentence, text was changed from “Results of the Mann-Whitney test indicate that the median annual discharge is not significantly different between the periods 1970–79 and 1989–2008 (fig. 22), although data in the earlier period are more widely distributed in the higher discharge range. Monthly medians for the two periods, however, indicate a shift in the pattern of runoff from snowmelt to monsoon-dominated flow. The median discharge was significantly less, at a 95 percent confidence interval, during 1989–2008 than during 1970–79 for the months February through May and September. During 1989–2008, there was a general flattening of the median monthly runoff response. Variability, as well as median discharge, was less for February through May and September. Variability increased in the upper discharge range during the months of June, July, and August when compared to 1970–79, although the median monthly values were statistically the same for the two periods. Change from a snowmelt to a monsoon-dominated flow regime has consequences for potential recharge to bedrock from the stream channel. Sustained snowmelt runoff provides more opportunity to recharge the underlying aquifer, whereas monsoonal runoff is of potentially greater magnitude but shorter duration, with little opportunity for recharge.” to “Results of the Mann-Whitney test indicate that the median annual discharge was not significantly different between the periods 1970–79 and 1989–2008, but median monthly discharges showed differences between the two time periods (fig. 22). The median discharge was significantly less, at a 90 percent confidence interval, during 1989–2008 than during 1970–79 for 7 of 12 months of the year. The period 1970–79 showed a greater range in monthly discharge values during March through May and September as compared to the period 1989–2008, while monthly discharge values in July and August showed a wider range of values during the later period.” Page 49, figure 22 was replaced with an updated version that corresponds to the textual changes described herein, and “Median annual and” was deleted from the beginning of the caption. Page 51, left column, first paragraph, text “The pattern of the exceedance curve agrees with the observation of monsoon-dominated flow during this period (fig. 22) that would be expected to provide less shallow groundwater for base flow than a snowmelt-dominated system” was deleted from the end of the paragraph. Page 51, right column, first partial paragraph, the following text was deleted from the end of that paragraph: “…, and reflecting, at least in part, the difference in dominant flow regimes between the two time periods.” Page 57, right column, first full paragraph, the second, third, and fourth sentences were altered from “… The Eagle Creek record does, however, indicate a change in the pattern of flow, with significant decreases in median flow for February through May and September from 1989 to 2008 as compared to 1970–79 (fig. 22). The change in flow pattern indicates a shift from snowmelt-dominated to monsoon-dominated runoff and potential changes in the volume of surface-water recharge to the bedrock aquifer. Although both the early (1970–79) and late (1989–2008) periods had below average precipitation, the period 1970–79 had no days without flow…” to “… The Eagle Creek record does, however, indicate a change in the pattern of flow, with significant decreases in median flow for 7 of 12 months from 1989 to 2008 as compared to 1970–79 (fig. 22). Although both the early (1970–79) and late (1989–2008) periods had below average precipitation, the period 1970–79 had no days without flow…” Page 63, left column, the second full paragraph was changed from “Results of the Mann-Whitney test indicate that the median annual discharge by water year is not significantly different between the periods 1970–79 and 1989–2008, although data in the earlier period are more widely distributed in the higher discharge range. Monthly medians for the two periods, however, indicate a shift in the pattern of runoff from snowmelt to monsoon-dominated flow. Change from a snowmelt to a monsoon-dominated flow regime has consequences for potential recharge to bedrock from the stream channel. Sustained snowmelt runoff provides more opportunity to recharge the underlying aquifer, whereas monsoonal runoff is of potentially greater magnitude but shorter duration, with little opportunity for recharge.” to “Results of the Mann-Whitney test indicate that the median annual discharge was not significantly different between the periods 1970–79 and 1989–2008, but median monthly discharges showed differences between the two time periods. The median discharge was significantly less, at a 90 percent confidence interval, during 1989–2008 than during 1970–79 for 7 of 12 months of the year.” ----------------------------------------------------- Description of Changes to November 2010 Revision Page 57, left column, last line: the number 0.28 has been changed to 0.03. Page 8, table 1, second column “Land-surface elevation”: the first eight values under “monitoring wells” have been changed: Original Revised 7,845 7,833 7,885 7,835 7,885 7,835 7,790 7,799 7,785 7,778 7,800 7,794 7,800 7,794 7,760 7,748 Page 35, figure 14: there is now a horizontal black line at the elevation 7,835 ft, tying into the phrase “Elevation of land surface.” Page 36, figure 15: there is now a horizontal black line at the elevation 7,994 ft, tying into the phrase “Elevation of land surface.”