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Page 4 Rgi Mottroe Patterson Pass Business Park The flat; low lying."flood plain" area to the south of.Patterson Run was not as clearly defined. Data points along transects from Patterson Run to the toe of slope of the agricultural area were used to determine the limits of the wetlandThis area is considered a "problem area. area- b;caise agricultural practices have changed the natural condition of the area and the wetland characteristics are risked by these.altered conditions. The top twelve Laches of the soil have lo,-en disced, disguising evidence of hydrology. However, in areas where there was strong oxidation (as a result of hyd.ic conditions), there were oxidized root channels, providing the secondary indicator of hydrology. The FAC-neutral test of the vegetation provided additional support for the wetland hydrology. Gleyed inclusions, concretions,. and orange mottles provided evidence of hydric soil conditions. The dominant plant species in this area werc seaside heliotrope (Helio.7opum curassavicum= OBL), Bermuda grass (Cynodon dacrvlo)r= FAC), creeping wild rye (Leymus triticoides= FAC), and alkali mallow (Malvella leproso= FAC). The upland boundary was defined by a dominance of upland plant species with no wetland soils and/or hydrology indicators (see Sheet 3). Vihen this area was re-examined in b4arch of 1998, the channel had changed its course, and during the high waters of this winters storms, the drainage flopled through the area previously delineated as wetland. Sedirnent d6posits cover the vegetation previously identified growing i,ti-us lov.-lying area. The 1'rrnits of the wetland/upland remains the sane, despite these altered conditions at the end ofthis drainage. This drainage is classified as z wetland. Area C Irea Cis a)7at basin to the west of Patterson Run at the northern end of that drainage. Thrs area had recently been disced, and there was little evidence of vegetation in that area. The soils in this area, however, appeared to have a higher silt component than the surrounding soils, indicating this area likely serves as an overflow basin, or floodplain.for the water at the northern end of the Patterson Run drainage before it flows into the culvert under the .Delta Mendota Canal. The elevation of the crossing noted on Sheet 3 is below 190: Figure 3 provides a detail of the topography in this area. The elevation of the top of the culvert' ander the Delta Mendota Canal.appears to be between 193'anf 194'. Area C as noted-,or Sheet 3 represents an average between,these two elevations. Area C is classifted as tivaters of the U.S. (see.Sheet 3). Drainage A This ephemeral drainage flows from a culvert under the California Aqueduct in a deep incised channel, at which point.the charnel is 15 feet across. As it flows across the'site, the channel narrows to 2 feet across: The banks ofthe channel are dominated by cultivated oats Much of the channel is unve.getated,with open water across much of the channel bottom F�.MI _ - - I��cs,AT;0 AL. lac. .. _. .. . . ...