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ORONO- SURFACE WATER MANAGEMENT PLAN <br />2 Physical Environment <br />This section describes the physical setting within Orono and includes climate, precipitation, geology and <br />soils information. The Minnesota statute that prompts Cities to prepare local surface water management <br />plans requires a land and water resources inventory section. The information presented here is intended <br />to augment information provided by the watersheds in their own plans. <br />2.1 CLIMATE <br />Orono has a Humid Continental Climate, typified by considerable seasonal temperature differences, hot <br />and humid summers, and cold to extremely cold winters, and is located in USDA Plant Hardiness Zone <br />4b. Native vegetation has a seven month growing season (April to October) and crops have a five month <br />growing season (May to September). Two-thirds of the precipitation occurs during the crop growing <br />season, with a total of almost 31 inches annually. Refer to Table 2-1 for a 30 year average of <br />temperature and precipitation Data. Refer to Point Precipitation Frequency Estimates provided by the <br />National Oceanic and Atmospheric Administration (NOAA) Atlas 14 for estimated precipitation amounts <br />for specific frequencies, durations, and locations at the link listed below. <br />hltps://hdsc.nws.noaa.gov/hdsc/pfds/pfds map cont.html?bkmrk=mn <br />Table 2.1: 1981-2010 Monthly Climate Normals (MPLS Flying Cloud AP) <br />Month <br />Jan <br />Feb <br />Mar <br />Apr <br />May <br />Jun <br />Jul <br />AugSep <br />Oct <br />Nov <br />Dec <br />Annual <br />Maximum Daily <br />23.6 <br />29.1 <br />40.6 <br />57.4 <br />69.7 <br />78.7 <br />83.1 <br />80.6 <br />71.5 <br />58.5 <br />41.3 <br />27.1 <br />55.2 <br />Temperature °F <br />Mean Daily <br />15.4 <br />20.3 <br />32.2 <br />47.2 <br />59.3 <br />69.0 <br />73.4 <br />70.9 <br />61.9 <br />48.9 <br />33.9 <br />19.5 <br />46.1 <br />Temperature °F <br />Minimum Daily <br />7.2 <br />11.4 <br />23.9 <br />37.1 <br />48.9 <br />59.2 <br />63.8 <br />61.3 <br />52.2 <br />39.3 <br />26.5 <br />12.0 <br />37.0 <br />Temperature °F <br />Average <br />0.74 <br />0.53 <br />1.77 <br />2.89 <br />3.60 <br />4.33 <br />4.20 <br />4.36 <br />3.54 <br />2.35 <br />1.74 <br />0.80 <br />30.85 <br />Precipitation in. <br />Source: National Oceanic and Atmospheric Administration <br />2.2 GEOLOGY <br />The geology of the region surrounding Orono is the result of two different geologic processes: <br />• Warm, shallow seas covered the area and created conditions for the formation of sedimentary rocks. <br />These formations are present as bedrock in the area. <br />• Glacial processes have resulted in the development of surficial geology, and therefore, the current <br />landforms. <br />The geology of the City can be generalized characterized as over 100 feet of glacial till/drift overlying <br />sedimentary bedrock. <br />BEDROCK GEOLOGY <br />The bedrock units present beneath the City are marine sedimentary rocks primarily of the Upper <br />Cambrian to Middle Ordovician ages (450 to 500± million years old). Ranging from deeper/older <br />bedrock to relatively shallow/younger bedrock, the geologic units present include the St. <br />Lawrence/Franconia formation, Jordan Sandstone, the Prairie du Chien group, and St. Peter Sandstone. <br />SURFACE GEOLOGY <br />Glacial influence on this area began around 2.5 million years ago and continued until about 10,000 years <br />ago. However, the landscape seen today was almost entirely influenced by activity between 30,000 and <br />City of Orono <br />Surface Water Management Plan February 2019 <br />