WSP12440 - Laserfiche WebLink

Home Browse Search

e e e 001,615 following discussion, along with photos and a map, document the river channel analysis done. A very preliminary cost estimate is also provided to establish a level of funding which is necessary to protect facilities along the river channel to safely pass flows higher than 5,000 cfs. It is estimated that approximately $500,000 is needed to construct earthen dikes and rebuild an irrigation diversion structure in order to test flows above 5,000 cfs. For continuous annual release of flows above 5,000 cfs, it is estimated that at least $12,000,000 may be required for additional channel protection, waste water system improvements, and public safety awareness. Channel Analysis: A monitoring team, Dick Kreiner with the COE and Rege Leach with the BOR observed the San Juan River channel on May 21, 22, and 29,1998. The observation was to evaluate the river channel with 5,000 cfs flowing and determine if additional flow can be safely routed. Observations from Farmington to Bloomfield were made on the river by the use of a hover craft. From Bloomfield to Navajo Dam, the river was observed ',bt points of known concerns for flooding. Numerous people contacted the team about"p05sible problems and all the reported locations were documented on a river channel map, attachment A, and with photographs, attachment B. The team validated that 5,000 cfs is the current channel capacity. Minor damage was occurring at this flow and would be escalated with an increased rate of now and prolonged time. A test release of flow higher than 5,000 cfs cannot be safely conducted without the construction of several small flood dikes and improvement to a diversion structure. Those specific improvements are: I. Construct a 75 foot long earthen dike to divert water from the Bond house and the Navajo Dam Water Users Association water system near the community of Navajo Dam. 2. Improve the Turley-Manzanares Ditch diversion structure to protect it from washout. 3. Raise or move the Valencia fishing cabin 4. Construct a 2,000 foot long earthen dike to protect a mobile home on the south river channel just upstream of the river bridge near the San Juan County fairgrounds. These ~our areas should be addressed before higher test fl<?w.~,Jlre attempte4._A _preliminary cost e~imate_for-doing-this_wQrk~~~OO,OOO. See attachment C for the specific cost estimate. The team felt that with river channel improvements, some increase in channel capacity was possible. However, an increase to 6,000 cfs would require a major effort. There were numerous other concerns that were observed and will need to be addressed before a permanent increase in channel capacity can be implemented. The full extent of these improvements cannot be completely quantified until higher test releases are made and observed. Other improvements that would be needed include channel bank protection and lor purchase of flood easements, additional diversion structure improvements, septic system improvements, and assistance with public protection from higher river flows. ~s.timate~or_this-workjn_ addition to the initial work to run a higher flow testis t 12,000,000 as detailed in attachment <;. --- -- .- - - -- - - - -- -. -. - - - - - -- - The intent oftl1is analysis was to determine if flows higher than 5,060 cfs could be safely passed by the San Juan River channel. The answer is yes, if improvements are made prior to higher test releases. The test releases will help to quantify the full magnitude ofthe improvements necessary to sustain an operation which requires periodic releases above 5,000 cfs. It is important to consider that releases above 5,000 cfs are significant b~cause it will impact many people along the San Juan River from Navajo Dam to the Animas River. ~oatternpLwas- made to quantify the affects of higher flows in the reach of San Juan River below the confluence -- ------=--------- - --