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2011 Annual Status Report <br />Aggregate Industries: Greeley F Street Site January 17, 2012 <br />occurred in pockets along the toe of the slope have died since also being inundated. But those <br />higher up the slope are thriving on what is now the new slope toe. Prior to the flood portions of <br />this slope appeared to have received water from an agricultural field to the west as well as a <br />culvert under the road on the west property boundary. <br />Russian -olive was treated in 2009, 2010, and again in August, 2011. Tamarisk (Tamarix <br />ramosissima), a Colorado "List B" noxious weed (Colorado Department of Agriculture 2010), <br />was treated in 2009 and 2010 and not observed in Area B in 2011. <br />ADDITIONAL DEVELOPING WETLAND AREAS <br />Large areas of herbaceous wetlands and willow- cottonwood woodlands are developing and <br />expanding along benches along the south edge of the West Side Pond. Some of these areas <br />occur at the toe of the excavation slopes. Vegetation that was formerly at the top of the sloped <br />terraces and that once formed islands above the water surface in 2009 is now emergent from <br />the open water in the aftermath of the 2010 flood event. Should the water level in the pond drop <br />as expected, the resulting heterogeneous mosaic of substrate and hydric conditions could <br />support natural colonization by surrounding herbaceous wetland vegetation. <br />Additional pockets of vegetation had been noted to be developing in areas on the south and <br />west slopes of the ponds. In these areas, the supporting hydrology appeared independent from <br />rising water in ponds. In many places, these areas were completely saturated and some <br />exhibited trickle surface flows with what appeared to be subsurface water intercepted by the cut <br />walls of the final pit excavation. These areas supported pockets of cattails with common <br />threesquare (Schoenoplectus pungens), rushes, sedges (Carex spp.) and spikerush. Stands of <br />plains cottonwood saplings and coyote willow occur throughout these areas. Much of these <br />areas were inundated in the 2010 flood and it is not clear how this will affect their development <br />in the long -term. <br />Summary and Comments <br />• The 2010 flood filled all three pit depressions on the F Street site. Although water levels <br />have receded, they remain considerably higher in 2011 than they were before the flood. <br />Where they will eventually stabilize is difficult to predict. It is expected that on -going <br />dewatering activities on properties immediately adjacent to the north may continue to <br />lower water levels on the F Street site. <br />• The flood and resulting inundation of vegetation resulted in the loss of some herbaceous <br />wetland areas, as well as trees and shrubs. However, some of these areas re- emerged <br />as water levels lowered and now occupy shoreline. These areas, and other wetland <br />fringe vegetation that has established along the new shorelines of standing water, are <br />expected to persist, moving with water levels, should they continue to lower. Over the <br />entire site, it appears the flood resulted in more potential wetland areas than were <br />negatively affected by inundation. <br />• The water level in Area A submerged the central shallow depression, the surrounding <br />wetland fringe, portions of the adjacent wet meadow, and toe of the surrounding upland <br />in 2010 and 2011. It appears that areas now on the shoreline of the standing water are <br />stabilizing as an herbaceous wetland fringe and will continue to develop and expand, <br />following the water levels. <br />4 <br />• <br />