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Section 3 <br />Strategies for Physical Conditions Affecting Surface Water Drainage <br />3.3 Physical Conditions Affecting Surface Water Drainage <br />Surface water quantity and quality is affected directly by the natural and manmade physical <br />conditions of the watershed's landscape. Changes to the land will affect he water quality and <br />quantity of downstream water bodies and groundwater. <br />Goals: ®. Minimize the negative effects of human activities which alter the <br />landscape and potentially harm healthy watershed function. <br />Maintain or improve the quality of surface water, including <br />prevention of water temperature increases in Valley Creek. <br />Prevent property damage or loss due to flooding. <br />Current Land cover in the Valley Creek watershed is mainly agricultural and low <br />Conditions: density residential, resulting in an overall low amount of imperviousness. <br />(Based on 1994 aerial photographs, three percent of the watershed is <br />covered by impervious surfaces.) This low amount of imperviousness is a <br />large reason why the current water quality in Valley Creek is so high and <br />can support a reproducing trout population. Although flooding is not <br />considered a major issue, there is ample evidence that occasional flooding <br />- occurs during spring snowmelt. There are two homes within the Fahlstrom <br />Pond floodplain. This is a landlocked area and high water levels have been <br />reported in 1969 and 1986. <br />Threats: 1) Development. Development pressure threatens the continued <br />healthy function of the watershed by adding impervious surfaces, <br />which can significantly increase the volume of runoff. This could <br />result in degradation of stream health due to higher volume of <br />surface water and pollutants (instead of cold, clean groundwater) <br />flowing through the creek, causing higher water temperatures and <br />possibly more erosion and flooding. Impervious surface can also <br />decrease the amount of water that reaches the groundwater aquifer. <br />-- These development pressures are real. The Valley Creek watershed- <br />- is located in one of the fastest growing counties in the nation. (Add <br />in growth projections for Afton and ~~oodbury} <br />2) Physical landscape features. Land altering activities which reduce <br />the stability of slopes (such as vegetation removal) can change the <br />drainage network of the watershed, cause erosion of soils, form <br />gullies, and degrade the health of the watershed and Valley Creek. <br />- -, , <br />~-~ <br />