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APPENDIX B TERMS OR ACRONYMS USED IN THESE PROCEDURES Critical habitat: River reaches formally designated as critical in accordance with the Endangered Species Act of 1973. as amended. Includes portions of the Colorado, Green. Duchesne. White, Yampa, and Gunnison Rivers and portions of the associated 100-year floodplains that contain areas essential to recovery of the endangered fishes. Direct Connection: Waters that flow directly into critical habitat. This does not include waters above reservoirs where escapement has been addressed in accordance with these Procedures. ESA: Acronym for Endangered Species Act. FEMA soecifications: Dikes built to isolate ponds from flooding must have a minimum of three feet of freeboard above the baseflood elevation. They must have a minimum of one additional foot of freeboard if the dike is within 100 feet of an area where the water is constricted. The upstream end of the dike must have a minimum of an additional one-half foot elevation of dike. The dike must be designed and constructed in accordance with recognized and accepted engineering methodologies. The dike must be "watertight. substantially impermeable to the passage of water. and be capable of withstanding hydrodynamic and hydrostatic forces, and the effects of buoyancy." For existing dikes to qualify, they must be certified via a written report by a qualified engineer. The report will consider depth of flooding, floodplain elevation, duration of flooding, embankment geometry, embankment and foundation materials. embankment compaction, penetrations. other design factors affecting penetration. channel constriction, and any other factors that may effect the ability of the dike to withstand flood events. Ordinary High Water Line (OHWL): This is the water level which represents the . water surface elevation during a normal (annual) high water event. The physical evidence denoting the OHWL is the point where perennial hydrophytic plant life converges with bare substrate (rock. gravel, sand. fines) or with substrate interspersed with annual vegetation. 5 feet above ordinary hiqh water line: This term refers to the vertical distance from the lowest point on the natural (or artificial/man-made) dike that forms the isolated pond to the ordinary high water line (OHWL) of adjacent streams. This height above the OHWL approximates the 50-year floodplain that is based on professional judgment and field observations of State and Service hydrologists and gaging tables for the Upper Colorado River Basin. Five and one-half feet above the OHWL approximates the 100-year floodplain. This is a relativ~ly simple method for approximating the 50- and 100-year floodplains that is accurate and definable during on-site visits. Isolated Ponds or Waters: Ponds or waters that have no connection with the river (no outlet). 19