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Spring <br />• Left Hand Creek comes up before the South Fork St. Vrain Creek due to the Left Hand Creek <br />basin's lower elevation. Runoff water is generally diverted to storage, although some <br />irrigation diversions may occur starting April 1. The diversion headgate continues to sweep <br />the low flows on the South Fork St. Vrain Creek for storage and/or irrigation uses. The <br />diversion headgate is opened up as the South Fork St. Vrain Creek comes up and the <br />headgate becomes operational after it thaws from its winter freeze. The Water Commissioner <br />checks storage levels in all of the reservoirs and diversion records at the end of the spring <br />storage season to determine if any water was stored out-of-priority. Any releases needed for <br />replacement to the St. Vrain Creek and/or South Platte River generally occur from <br />• The ditch company bypassing water from the South Fork St. Vrain Creek headgate that <br />the Water Commissioner conveys to the South Platte River, <br />• C-BT units, or <br />• Reservoir releases. <br />Early summer <br />• The South Fork St. Vrain Creek diversion headgate continues to sweep the river as flow <br />levels after spring runoff generally fall below the ditch company's senior water right of 40.77 <br />cfs. Although occurring infrequently, the ditch company bypasses 3 cfs - 5 cfs flow when the <br />river comes up after rain events to satisfy downstream water rights with water rights senior to <br />ditch company's junior, 1870 water right (e.g., Rough and Ready Ditch, James Ditch). C-BT <br />releases are made to shareholders starting May 1 if diversion capacity in the Boulder Feeder <br />Canal is available. Releases may also be made from Left Hand Valley Reservoir and Allens <br />Lake to supplement low flow deliveries from direct flow rights. <br />There are five ditch headgates within the Left Hand Ditch Company that can receive C-BT <br />water directly, as shown in the gray area to the right of the Boulder Feeder Canal on Figure 2. <br />Five of the 12 ditches currently active in the ditch company can be served directly by Left <br />Hand Valley Reservoir. The seven upper ditches benefit by diverting water from Left Hand <br />Creek in exchange for reservoir releases made to the lower ditches. Since about 1992, storage <br />in ditch company reservoirs has been used to make small summertime replacements to Left <br />Hand Creek as part of the St. Vrain Left Hand Water Conservancy District (SVLHWCD) <br />substitute water supply plan. SVLHWCD deliveries are made pursuant to its share ownership <br />in the ditch company and SVLHWCD C-BT units used by the ditch company. <br />Late summer <br />Releases are made from the high mountain reservoirs to supplement irrigation demands. C- <br />BT deliveries also continue to be made. Access to Lake Isabelle is limited by its location in a <br />Wilderness Area and dependent on the vagaries of high-mountain weather. The ditch <br />company generally opens the Lake Isabelle outlet pipe around August 1 and closes it around <br />September 1. Access to Left Hand Park Reservoir is better than for Lake Isabelle and is <br />generally used along with, or after, the Lake Isabelle releases. Depending on the type of year <br />just passed and projections of the coming year, remaining high mountain storage at the end of <br />the summer may be moved down to Allens Lake and/or Left Hand Valley Reservoir in the <br />early fall to make room for the upcoming storage season. <br />Left Hand Ditch Operating Memorandum.doc 15 of 17 January 5, 2005 <br />