Minnesota Wetland Conservation Act Notice of Application-2010

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The definition of appropriate hydrology according to the 1987 Nlanua( includes two important terms that must be clarified. Eirst, the detinition of a growing season is needed. The growinb season is defined in the 1987 Nianual as: "...the portion of the year when soi! temperature (measured 19.7 inches be(ow the surface) is above bio(o�ical zero (�° C o�•41' F)." According to the 1987 Manua( this period of time can be approximated by using the "starting and ending dates for the growing season based on a 28' F air temperatu��e threshold at a frequency of � years in 10." Based on this definition the growin� season ranges approYimately 160 days to 130 days in the Minneapo(is/St. Paul metropo(itan area(160 in the northern suburbs and greater to the south). Therefore, the required inundation or saturation to the surface for �% of the growing season would be 8 or 9 consecutive days that ground water would need to be at the surface or saturated to the surface. The second term in the appropriate hydro(ogy definition from the above paragraph to be clarified is "in most years". This means in � of l0 years hydrolo�y must eYist within a `�urisdictional wetland" for the 8 or 9 consecutive days of the growing season. This means that one observation date or even one whole year worth of detailed hydrology data may be deemed insufficient to determine if appropriate hydrology exists at a given location. [n the event that precipitation events accumulate to above or below normal ducing just prior to a site visit or during a more intensive hydro(ogy study, the data may be confounded by non-normal circumstances and may be considered outside the bounds of "most years". Idea((y, both antecedent soil moisture conditions and pcecipitation would be normal during all delineations. However, this is not a realistic impression of climate. Therefore, primary indicators of hydrology must be reviewed with scrutiny prior to determining if hydrology indeed exists. Wetland hydrology may be observed as standing water (inundation), or may be observed as freestanding water within a soil pit or auger hole (saturation) usual(y within the uppec 12 incl�es. This is what would be considered primary hydrology indicators. Examination of this indicator requires diaging a soil pit to a depth of 16 inches and observing the level at which water stands after sufficient time has been a((owed for water to drain into the hole. The required time will vary dependin� on soil texture. This leve( represents the depth to the water tab(e; the depth to saturated soils will always be nearer the surface due to the capillary fringe. According to the Hydrology criteria in the (987 Delineation Manual, for soil saturation to impact vegetation, it must occur within a major portion of the root zone, typically within 12 inches of the surface. Only one primary indicator is necessary to make the determination that wetland hydrology is present. However, since a single observation is not enou;h evidence, based on the percentage of the growing season this inundation or saturation is required, these data are only valid when reviewed while also considering the abundance of recent precipitation events or the seasonal trend of climate when the site visit was made (this may be done through review of precipitation records where available). In addition to the primary indicators of �vetland hydrology, there are secondary indicators (e.g. oxidized root channels, water-stained leaves, local soil survey data, FAC-Neutra( test), of which two must be present to consider the sample point as having wetland hydrology. A-2