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14 BOYLE.': I I I I I I I I I I I I I I I I I I I Chapter III . Background Information structure, the State has indicated that they are not comfortable accepting the Class III dam classification due to possible impacts on future downstream development. Therefore, to justifY the existing 100-year spillway capacity for future downstream development, an IDA was performed. The IDA was performed to define the baseline floodplain limits for future downstream development. Future development will be restricted outside of the defined IDA floodplain limits so not to trigger a reclassification of the dam by the SEO. An IDA is based upon comparison oftw() floods: base flood and dam break flood. The base flood is a percentage of the PMP which wi!] cause a dam failure by overtopping, and then routing the flood downstream assuming no dam is in place. The dam break flood is the flood resulting from an overtopping dam failure due to the base flood. The area between the compared flood stage elevations is the incremental zone. The IDA results are presented in Figure 1II-2. The present downstream development is outside of the flood inundation limits. The Colorado State Rules and Regulations for Dam Safety and Dam Construction Rule S.A.(S)(c) states "". The spillway capacity and IDF will be acceptable where it can be shown that the dam fiiilure flood would cause no expected additional loss of life and would not cause significant incremental flood damages downstream." The results verifY that the downstream incremental flood effects are within the SEO guidelines for a spillway with a 100-year flood capacity and therefore, the SEO accepted the existing spillway capacity for the project. E.2 Water Rights No court decree adjudicating water storage rights from Monument Lake has been located. Monument Lake has been storing water since it was completed in 1893 as a result of Colorado Legislative authorization in 1891. A possible conclusion which could be drawn from this is that the Legislature, by enacting the 1891 Statute intended to legislatively create a water right with priority date as of the date of passage of the act for storage of water in Monument Lake for the purposes therein stated. Legislature had the pOWer to create such a water right under our Constitution. The Town filed for water storage rights on December 29, 2000 and was assigned case number 00CW146. The following generally describes the historical use of the reservoir. Monument Lake Dam Feasibility Study