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July 1993 -12- 923-2515 <br />4.0 ECOLOGICAL II~fVESTIGATION <br />4.1 Methods of Identification and MaRpine <br />Existing Flood Irrigation Areas, Irrigation Ditches and Diversion Points: Information was <br />obtained from field reconnaissance and the following sources: The Mount Hams, Colorado, <br />1971, U.S. Geological Survey (USGS) 7.5 minute topographic map, color aerial photography <br />(1" = 1000', July 1, 1988), water rights data (Tipton and Kalmbach 1989), discussions with <br />land owners and personnel of Peabody Western Coal Company, U.S. Agricultural Stabilization <br />and Conservation Service (ABCs), U.S. Soil Conservation Service (SCS), and Colorado Division <br />of Water Resources (CDWR) contacted during the course of the study. <br /> <br />Subirrigated Areas: The process for identifying subirrigated areas in native vegetation was <br />based on the presence and abundance of hydrophytic vegetation, soils data, plant rooting depth <br />data, topography, and hydrology data. <br />Plants present in potential subirrigated areas were identified and their hydrophytic status <br />(obligate wetlands, facultative wetlands, facultative, facultative upland, and upland) was <br />determined as classified by Reed (1988). First, those azeas with a relative abundance of obligate <br />and facultative wetland plants were identified as potential subirrigated azeas. Next, the soil type <br />of the potential subirrigated areas, the depth to water, and the effective rooting depth of plants <br />was determined from recent SCS (1991) unpublished data and mappings. The topographic <br />position of the potential subimgated area with respect to drainage channels and the depth of the <br />channel below the soil surface was noted. Finally, the presence or absence of surface water in <br />the adjacent drainage was observed and the condition (saturated versus unsaturated) of the soils <br />on the stream bank and bottom was recorded. <br />C~ <br />Golder Associates <br />