Laserfiche WebLink
<br />~~ <br />of wetland hydrologic support from the canal has not been determined, although <br />much of the wetland area is not visible or is reduced in size based on 1949 black and <br />whNe photography taken prior to canal construction. <br />' Both drainages have been historically modfied for irrigation conveyance and are <br />currently maintained for that purpose. Lateral ditches connect the drainages and <br />' divert surface water into adjacent fields. <br />Cattail (Typha spp.) vegetation occurs in the impounded areas along with bulrush <br />' (Schoenoplectus lacustris) and other obligate wetland species. Wetland (orbs and <br />grasses (Schoenoplectus pungens, Carex spp., Juncus spp., Phalaroides <br />arundinaceae) dominate the remainder of the dranageway. An occasional peach- <br />' leaved willow (Salix amygdaloides) and scattered sandbar willow (Salix exigua) occur <br />throughout, but are more abundant in the upper portions of the drainageways. <br />5.2.2 West Valley <br />Several minor drainageways and swales are located in the west valley. These <br />wetlands either contain an intermittent surface drainage or are supported by <br />subsurface groundwater. Each arises in close proximity to the St. Vrain Supply <br />' Canal, suggesting some level of hydrologic support ftom the canal. Historic existence <br />of these wetlands prior to canal construction is unclear, although many of the wet <br />areas are not visible or are reduced in size based on the 1949 black and white <br />' photography. Weiland boundaries in the west valley may be considered dynamic in <br />nature due to the apparent hydrologic influence of the St. Vrain Supply Canal. <br />' Evidence of irrigation modification in the form of small impoundments and lateral <br />ditches is apparent in many of the drainages and swales. <br />' The vegetative composition of the wetlands in the west valley is similar to that <br />described for the east valley. <br />' 5.2.3 Irrigation Ditches <br />' Seven isolated wetlands areas are found amongst the four irrigation ditches which <br />flow from west to east across the southern portion of the project. All are grazed quite <br />' heavily and exhibit sedge (Carex spp.) and three-square (Schoenoplectus pungens) <br />as wetland vegetative indicators. The riparian vegetation of cottonwoods (Populus <br />spp.) and willows (Salix spp.) found immediately adjacent and within the ditch banks <br />' does not qualify as jurisdictional wetland. <br /> <br /> <br />