2010-12-17_REVISION - C1981019 (106)

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RULE 2 PERMITS Findings Field conditions at the time of site evaluations in August, 2005 were ideal for the evaluation of all three variables necessary for wetland determination (vegetation, hydrology and soils). Floral growth in most areas was mature, highly productive, readily identifiable, and had not been overly grazed by domestic livestock or wildlife. Given the streamside nature of the majority of wetlands, hydrology (typically soil saturation) was also ideal for observation. In addition to experiencing ideal field conditions during August, the new CIR aerial imagery that was exposed during late September, 2005 while wetland vegetation was still actively growing, but upland vegetation was senescing, was ideal for mapping. At the time of sampling perennial stream reaches were noted to include: Wilson Creek, Jubb Creek, and Collom Creek (including a majority of the East Fork of Collom). All other drainages were observed to be intermittent or ephemeral. It's possible that the upper portions of the main stem of Jubb Creek and Collom Creek are intermittent in most years as elevated moisture in 2005 may have led to an extension of annual flows. Perennial reaches generally exhibited a defined bed and bank and as such classify as a WUS, although some areas (especially Jubb Creek and lower Collom Creek) routinely exhibited a grass - lined channel that facilitates classification of the watercourse as a wetland rather than WUS. The wetlands along the project area stream courses are typical of Colorado mountain valley wetlands ranging from moist and wet meadows (within alluvial deposition areas) to heavily vegetated herbaceous strips (along stream banks). These wetlands are typically heavily vegetated herbaceous meadows to moist meadow communities because they receive moisture from lateral subirrigation along the stream channel. On occasion, wetlands developing along the margins of older more stable stock tanks exhibit emergent wetland communities. The majority of the wetlands within the Collom permit expansion area occur over a rather broad continuum, especially lower in the watershed where stream courses flow over (or more typically have excised into) alluvial / colluvial floodplains. It is in these lower areas where the six larger wetlands were observed. It appears that most of these larger wetland areas receive their primary maintenance water from perched groundwater discharge in the form of seeps and springs located along the margins of the alluvium / colluvium, but also from subirrigation due to the porous soil materials (sands and gravels) underlying the surface soils as well as run -on from the side slopes and flood flows escaping the confines of active channels. In most circumstances, sufficient moisture was observed to be delivered to these wetlands because areas of standing water were readily apparent. To the contrary, one of these six larger wetland areas (Wetland #4) located in the East Fork of Jubb Creek just above the confluence with the West Fork, is in a state of transition to upland. It appears that primary hydrology must have come as saturation of alluvial materials and subirrigation from flood flows. However, given stock tank development upgradient of this wetland, flood flows and /or subirrigation no longer saturate the surface with sufficient periodicity to preclude invasion by upland taxa. The majority of study area wetlands tend to exhibit similar properties with very dark soil matrix colors, bright mottles, typical saturation to the surface or near surface, and dominance by sedges and wetland grasses and forbs. Areas transitional to upland are typically governed by elevation, slope, and soil textures that preclude ponding or subirrigation of soils in the upper 12 inches of the soil profile. The most notable characteristic governing the location of (or simply correlated to) the wetland / upland boundaries, especially along the transitional margins of these fluvial areas, is the often not so subtle changes in elevation, topography, or soil porosity (usually 12 or less inches of elevation) which has resulted from historic fluvial erosion and deposition processes along the stream banks. These wetlands are characterized by a series of related vegetation communities variably dominated by a variety of taxa Collom — Rule 2, Page 73 Revision Date: 1/23/09 Revision No.: PR -03