Agenda - Council - 09/14/2021 - Laserfiche WebLink

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Trott Brook North Property, Ramsey Wetland Delineation Report Signatures at locations of potential wetlands on aerial photographs were interpreted and classified using seven codes (Table 4). Table 4. Aerial photograph interpretation codes Code Classification CS Crop stress DO Drowned out NC Not cropped SW Standing water WS Wetland signature AP Altered pattern NV Normal vegetation This analysis used only aerial photographs taken following periods of average normal antecedent precipitation within the normal range as determined using the Wetland Delineation Precipitation Data Retrieval tool (Minnesota Climatology Office 2015). This tool classifies antecedent precipitation as Normal (N), Wet (W) or Dry (D) by comparing precipitation during the three months preceding the estimated date of aerial photography to the 30-year average from 1981- 2010. All available Google Earth and MnGEO FSA photo years were assessed for wet/normal/dry climatic conditions using the Wetland Delineation Precipitation Data Retrieval tool as summarized in Table 5 below. Based on the results of Table 5, available aerial photographs from the 5 most recent and available normal year photos (2015, 2017, 2018, 2019, and 2020) were used for the offsite hydrology review. Table 5. Decision matrix for offsite hydrology review. Source Photo Date Date Used for Climate Assessment Climatic Conditions Result Google Earth 10/9/2020 10/9/2020 Normal Used (1) Maxar Tech. 10/25/2019 11/1/2019 Wet Most recent wet year used to ID signature areas FSA 7/1/2019 7/1/2019 Normal Used (2) Google Earth 4/28/2018 5/1/2018 Normal Used (3) FSA 8/31/2017 9/1/2017 Normal Used (4) Google Earth 4/5/2017 4/5/2017 Dry Not used, dry conditions Google Earth 3/11/2016 3/11/2016 Normal Not used, prior to growing season FSA 9/15/2015 10/1/2015 Normal Used (5) 1 2019 metadata NA; date of 7-1-2019 assumed. 7