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Applicant's Response to Second Adequacy Letter Grand River Park Project, DRMS File M-2006-046 January 2, 2007 Page 12 Please see the response to Comment 21b in the attached report prepared by Martin & Wood Water Consultants. It appears that previous exploratory and monitoring work may have provided an estimate for the relative maximum depth of the groundwater surface across the site. The groundwater surtace appears to vary between zero and five feet depending on time and location of measurement. Based on limited information available to date, it is possible that seasonal variation accounts for the range of groundwater depths observed on the site; it is also possible that the observed range of depths to the groundwater surface is the result of local variations in topography and flow within the property boundary, or climate and other factors producing variable groundwater conditions regionally. Wetland plants appear to thrive on the site in areas that are perennially mucky, very likely with little to no separation between the wetland root zone and the groundwater surface. While the groundwater table is exceptionally shallow and even emergent in some parts of the site, field reconnaissance also shows that woody plants on the site are rooted in firmer soil, moist but not perpetually inundated. It is the applicant's conjecture that desirable woody plants have generally succeeded on the site where the groundwater table is distinct from the land surtace (e.g., an average of 2 feet or greater beneath the ground surface, providing a stable growth medium) or where soils are, at a minimum, subject to seasonal cycles of relative wet and dry. However, the number of riparian cottonwoods and willows on the subject property is so limited, the value of any detailed study of their relationship to groundwater is also very limited. As the consulting biologist, Steve Dahmer of Environmental Solutions, wrote (in the Wildlife and Habitat Assessment report attached for your reference), "Fremont cottonwoods are notably scarce, even along the river, with only a handful of mid- sized trees present. Other segments of the river corridor, both above and below the Property, have extensive stands of cottonwoods, comprised of many age- classes.... There is a small contingent of Hawthorn, Coyote willow, Planeleaf willow, Wood's rose and Skunkbush also scattered throughout the property, though Russian olives are rapidly excluding those more desirable species." While intensive study of groundwater as a sustaining factor for riparian woody plants may be justified where this type of vegetation is of significant size and ecological value, self-regenerating, and uniquely reliant on a stable groundwater condition for growth, none of those conditions compels such study at the subject site. Desirable plants are scattered and do not form significant stands, are being out-competed by invasive, noxious woody plants, and are generally located in the proximity of surface water sources (e.g., the floodway of the river, irrigation ditches), which may provide a significant amount of soil moisture to promote plant growth.