Appendix A Natural Environment Study (Minimal Impacts)

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JURISDICTIONAL DELINEATION REPORT FAIRVIEW STREET IMPROVEMENTS A N OVEMBER 2018 FROM 9TH STREET TO 16TH STREET AND BRIDGE REPLACEMENT PROJECT `J" SANTA ANA, CALIFORNIA Hydric Soils Hydric soils' are defined as soils that formed under conditions of saturation, flooding, or ponding long enough during the growing season to develop anaerobic conditions in the upper part .2 Soils are considered likely to meet the definition of a hydric soil when one or more of the following criteria are met: 1. All Histels except Folistels and Histosols except Folists; 2. Soils that are frequently ponded for along duration or very long duration' during the growing season; or 3. Soils that are frequently flooded for a long duration or very long duration during the growing season. Hydric soils develop under conditions of saturation and inundation combined with microbial activity in the soil that causes a depletion of oxygen. Although saturation may occur at any time of year, microbial activity is limited to the growing season, when the soil temperature is above biologic zero (the soil temperature, measured at a depth of 20 inches, below which the growth and function of locally adapted plants are negligible). Biogeochemical processes that occur under anaerobic conditions during the growing season result in the distinctive morphologic characteristics of hydric soils. Based on these criteria, a National List of Hydric Soils was created from the National Soil Information System database and is updated annually. The Regional Supplement has a number of field indicators that may be used to identify hydric soils. The United States Department of Agriculture (USDA) Natural Resources Conservation Service (Schoeneberger 2002) has also developed a number of field indicators that may demonstrate the presence of hydric soils. These indicators include hydrogen sulfide generation, the accumulation of organic matter, and the reduction, translocation, and/or accumulation of iron and other reducible elements. These processes result in soil characteristics that persist during both wet and dry periods. Separate indicators have been developed for sandy soils and for loamy and clayey soils. Wetland Hydrology Under natural conditions, development of hydrophytic vegetation and hydric soils is dependent on a third characteristic: wetland hydrology. Areas with wetland hydrology are those where the presence of water has an overriding influence on vegetation and soil characteristics due to anaerobic and reducing conditions, respectively (Corps 1987). The wetland hydrology parameter is satisfied if the The hydric soil definition and criteria included in the 1987 Manual are obsolete. Users of the 1987 Manual are directed to the United States Department of Agriculture (USDA) Natural Resources Conservation Service website for the most current information on hydric soils. Current definition as of 1994 (Federal Register 1994). A long duration is defined as a single event ranging from 7-30 days. A very long duration is defined as a single event that lasts longer than 30 days. \\vcorp12\projects\WKE1702\N ES- MI\November 2018 Sub mittal\Fairview Street I m proveme nts_Draft JD 110918.docx all/09/18»