DCPZP-2009-00025 - Laserfiche WebLink

Home Browse Search

• Page 2 of 6 grass and blue grass are difficult to identify during the winter. For this site, reed canary grass, blue grass and brome grass were the dominant plant species on the site. e. Many forbs are also quite identifiable during winter even though dormant, such as goldenrods and asters. This site is dominated by those plants plus common milkweed and wild carrot; both non- wetland plants. f. The most difficult plant to identify outside the floral bloom and particularly during the winter are sedges and rushes. Most often with sedges and rushes you can narrow the plant down to family but not get the precise plant until it is in bloom. In those instances, because all but a few of these species are upland plants, sedges are rushes are classified as wetland plants. 3. Hydrology: a. Observing ground water during winter is problematic if soils are frozen. When that occurs then wetland delineations should not be undertaken in the winter; wetland determinations can be undertaken as an alternative. b. When the ground is soft if ground water is present it can be recorded, so time of year is not an issue in that context. c. During winter months ground water levels are often reduced, but that too is not much of a problem if we are looking at ground waters indicators such as: i. Presence of mapped hydric soils that match the mapped soil unit. ii. Evidence of ponding or flooding which is seen from water stains on tree trunks. iii. Evidence of drainage patterns (this requires no snow on the ground in most cases) but is usually limited to Riverine systems where drainage patters or most evident. iv. Presence of redox features immediately below the top soil or within the topsoil layer and within 12 inches of the ground surface in many instances. 4. Topography: The more distinct the topography the easier it is to locate the wetland line during the winter. If topography is gradual as is the case for part of this site, then it is less of a factor. On the matter of wetland delineations in general, there are procedures for doing both an off-site and on-site delineations: • The off-site delineation procedure, though no commonly used, relies upon a variety of empirical data to seek to determine the approximate wetland boundary locationi. Such tools are: aerial photographs, infra-red imagery, soil maps, topographic surveys, previous soils surveys done by others, mapped waterways, etc.... Although not entirely reliable as a means to locate the exact wetland boundary, this technique is used and was used by the NRCS to map farmed wetlands and is a recongnized protocol by the FWS, EPA, NRCS, COE and WDNR in some instances. • On-site wetland delineations must done according to the 1987 Wetland Delienation Manual, the State Guidelines for Mapping Wetlands when mapping wetlands below the ordinary high water mark of state waters; the 1998 Wetland Mapping Conventions for Agricultural Land; the St. Paul District guidelines for delienating wetlands in Minnesota and Wisconsin, On the matter of growing season, as we discussed, the growing season is based upon annual crops, primarily farm crops, that will grow between those periods of the last seasonal frost condtions in the spring and the first seasonal frost condition in the fall of each year. For each County the growing season start and stop date is based upon average periods (number of days) between those two events and is based upon a 30 year period. Because wetland plants are perennial species they begin to grow before the last seasonal frost in the spring to well beyond the first seasonal frost in the fall. The real key to growing season limits, which occurs on year to year basis, is ground frost. If the ground is not frozen and ground temperature within 12 inches (root zone for most plants) of the ground surface is above 28 degrees then for manys species, such as trees and shrubs, they will continue to grow. Other factors are presence/absence of snow cover, presence of ground moisture or groundwater in some cases, and sunlight. For forbs and grasses that mgiht grow that are not dormant absence of snow is a key factor. I agree with Cami that winter delineations when done should be verified in many instances when site conditons allow for idenfifcaiton of plants and when looking at many secondary indicators of hydrology. However, there are instances when a winter delination is possible. For the Holland Fields Lot 11 site, I first did a wetland determination to see if I could map wetlands based upon the site's conditions. I found conditions favorable enough to do the work, As a result, I was able to demonstratie that the wetland line did move uplsope in many areas as was suggested it might have done; that was a good call by your staff. This alone renders the work more creditable than not. Never-the-less, a spring verification of plant types of percent cover could be done to make the wetland effort more complete. If necessary, I will be glad to return to the site and look it over after the snow is gone. 1/28/2009