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-4- • 1931 to 1960 and values derived by correlation with physi- ographic features. The maps are now out of print. The basin weighted mean annual precipitation for each stream gauge is summarized in Table 1. A generally increasing relationship was found between greater normal annual precipitation and greater runoff volume. The relationship is shown in Figure 1 titled North Park Runoff Correlation, along with the line and equation of best fit for the data. The correlation between mean annual precipitation and normal annual runoff was not precise, the R2 value was only 0.54. Extrapolation of the regional rainfall runoff data indicates that no runoff is expected for mean annual precipitation values less than about 16 inches. This would indicate, therefore, little to no surface runoff at the mine site. The new gauge installed by the U.S.G.S. on Williams Draw consists of a 9-inch wide by 15 inch high parshall flume set • in a 15 foot long by 5 foot wide and 2 foot high concrete weir. Telephone conversations with the U.S.G.S. concerning the gauge installation indicate that the rating curve for the site is identical with the rating curve for a 9-inch parshall flume for heads up to 1.25 feet. The rating curve above this point has not yet been established, but will be established by the analysis of indirect flow measurements. It is believed that the stream gauge records are still contained in the recording device at the gauge site. The stream gauge was observed and gauge heights were recorded by personnel of Kerr Coal Company six times during the recent runoff season. A rating curve was established to extend the rating curve for the 9-inch parshall flume above heads for 1.25 feet. The rating curve considers weir flow (Q=CLH3/2~ over the top of the gauge. The rating curve is included in • the Appendix of this report. Figure 2 is a hydrograph which was constructed from the six measured points. It has runoff Leonard Rice Consulting Waler Engineers.lnc.