2022-04-04_PERMIT FILE - M2022013 (32)

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Ecological Site Concept The Sandy Plains ecological site is a mixed grass prairie site dominated by warm-season tallgrasses with an understory of warm-season shortgrass.Cool-season midgrasses are secondary.A variety of(orbs and shrubs occur on the site.The site occurs in upland positions on plains. Physiographic Features This site occurs on interdunes in dune fields and on terraces or narrow to broad,flat interfluves on dissected plains. Landform: (1)Interdune (2)Interfluve (3)Terrace Minimum Maximum Elevation(feet): 3400 6000 Slope(percent): 0 6 Water table depth(inches): 80 80 Flooding Frequency: None None Ponding Depth(inches): 0 0 Frequency: None None Runoff class: Very low Medium Aspect: No Influence on this site Climatic Features Average annual precipitation across the MLRA extent is 14 to 17 inches,and ranges from 13 inches to over 18 inches,depending on location. The average is 15 inches.Precipitation increases from north to south.Mean Annual Air Temperature(MAAT)is 50oF in the northern part and increases to 52°F in the southern part.Portions of Morgan and Weld counties(in the northern part)are cooler and drier,the MAAT is 48°F, and average precipitation is 13 tol4 inches per year.Two-thirds of the annual precipitation occurs during the growing season from mid-April to late September.Snowfall averages 30 inches per year,area-wide,but varies by location from 20 to 40 inches per year.Winds are estimated to average 9 miles per hour annually.Daytime winds are generally stronger than at night,and occasional strong storms may bring periods of high winds with gusts to more than 90 mph.High-intensity afternoon thunderstorms may arise.The average length of the freeze-free period (28°F)is 155 days from April 30th to October to 3rd.The average frost-free period(32°F)is 136 days from May 11 th to September 24th.July is the hottest month,and December and January are the coldest months.Summer temperatures average 90oF and occasionally exceed 100°F.Summer humidity is low and evaporation is high.Winters are characterized with frequent northerly winds,producing severe cold with temperatures occasionally dropping to-30oF or lower.Blizzard conditions may form quickly.For detailed information,visit the Western Regional Climate Center website:Western Regional Climate Center>Historical Data>Western U.S.Climate summaries,NOAA Coop Stations>Colorado http://www.wrcc.dri.edu/summary/Climsmco.html Eastern Colorado was strongly affected by extended drought conditions in the"Dust Bowl"period of the 1930's,with recurrent drought cycles in the 1950s and 1970s.Extreme to exceptional drought conditions have re-visited the area from 2002 to 2012,with brief interludes of near normal to normal precipitation years.Long-term effects of these latest drought events have yet to be determined.Growth of native cool-season plants begin about April 1 and continue to mid-June.Native warm- season plants begin growth about May 1 and continue to about August 15.Regrowth of cool-season plants occur in September in most years, depending on moisture.Note:The climate described here is based on historic climate station data in the past 30 to 50 years,and is averaged to provide an overview of annual precipitation,temperatures,and growing season.Future climate is beyond the scope of this document. However,research to determine the effects of elevated CO2 and/or heating on mixed-grass prairie ecosystems,and how it may relate to future plant communities(i.e.potential shifts in dominant and sub-dominant groups,changes in growing season length,responses of cool- season and warm-season grasses,etc.)is on-going. Averaged Frost-free period(days): 129 Freeze-free period(days): 150 Mean annual precipitation(inches): 15.89 Monthly Precipitation(Inches): Jan Feb Mar Apr May Jun Jul AugSep Oct Nov Dec High 0.48 0.47 1.29 2.06 3.04 3.05 3.07 2.97 1.58 1.69 0.85 0.49 Medium 0.27 0.28 0.69 1.25 1.93 2.11 2.13 1.92 1.01 0.70 0.44 0.28 Low 0.11 0.10 0.34 0.58 1.17 1.30 1.32 1.13 0.50 0.32 0.20 0.14 2 of 18