SPDSS_Task91_MapIrrigationDistributionSystems_20070109

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MEMO -TASK 91 Water commissioners provided some contact information, but other sources were also used including: WaterColorado.com, Ditch and Reservoir Company Alliance (DARCA), State of Colorado Division of Water Resources Division 1 Engineer's Office, individual farmers, phone books, and the Internet. 2.4.3 Contacting and Meeting with Ditch Companies The first contact with ditch companies was by mail. Letters were sent to each ditch company describing the project and requesting a meeting with knowledgeable personnel. Phone calls followed the letters to schedule meetings and most ditch companies eventually agreed to meet with RTi. In Division 1 only four ditch companies declined to review the maps: Louden Ditch and Reservoir Company, Platte Valley Irrigating Company, Williamson Ditch, and Zweck Turner Ditch Co. A full description of the methods used in contacting and conducting meetings with the ditch companies is presented in Appendix C. All contact information about water users was compiled in a Microsoft Access database for ease of use and data management. The database stored contacts and information about all RTi contacts with water users, including phone calls, meetings, and edits to their service areas. A digital report containing the entire contents of the `Ditch Company Contact Database' will be delivered to the State at the end of Phase 3. Appendix D is an example of the contents of the database report. The ditch companies were very helpful and knowledgeable about their service area. They provided corrections to the maps when a parcel was not irrigated by their ditch, irrigated by another ditch, or not irrigated at all. Many ditch companies provided information on which parcels were irrigated by surface water only, supplemented with a well, or irrigated entirely from an irrigation well. A few of the larger ditch companies had difficulty providing information at the parcel level. This was generally found with ditch companies that supplied water to distribution laterals managed by smaller companies, or run by multiple ditch riders. In these cases the ditch company personnel usually stated that they do not administer the water past a certain headgate or location. RTi made contact with several of the secondary lateral companies and multiple ditch riders. RTi did not contact individual farmers about water use. All of the meetings with ditch companies, including secondary lateral companies, were logged in the `Ditch Company Contact Database' . The meetings provided a basis for obtaining valuable information, and gauging the accuracy of the initial preliminary irrigated parcel data that proved to have been very reliable. The service areas that did need corrections often had irrigation above the main ditch, or parcels irrigated by multiple diversion structures. Corrections made by water users mostly involved changing the water source for parcels. Some of the preliminary parcels mapped were under a different irrigation service area than was originally assigned. However, there was little non-irrigated acreage originally mapped as irrigated. Table 3 shows the difference in irrigated acreage before the meetings and after the meetings. The acreage in all the districts, except District 64, decreased because of the meetings. This was expected, as most of the acreage corrected to `not irrigated' had already been attributed as `potentially non-irrigated', the water-users input confirming this. Table 3. Irrigated Acreage Changes after Water User Meetings Water District Original Irrigated Area (Ac) Updated Irrigated Area (Ac) Irrigated Area Difference (%) 1 368,672 324,334 -14% 2 163,094 130,250 -25% 3 158,070 143,415 -10% 4 54,628 62,448 12% 5 57,214 59,020 3% Page 8 of 55 ~R~versfde FecAno[o`(!~Y fnc. 4'JaYer Resources Errgi~ecr:np an~i L~ar+suFlrnd