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Update on Demand Forecasts <br />such as limitations on or prohibition of bluegrass lawns will be evaluated as <br />alternatives. <br />Agricultural Demand Forecasts <br />Preliminary estimates of current agricultural water demands were made from the <br />Colorado River Decision Support Systems (CRDSS) for the Colorado, Gunnison, <br />Yampa/ White/ Green and San Juan/ Dolores/ San Miguel basins and the Rio Grande <br />Decision Support System (RGDSS) for the Rio Grande. Preliminary estimates were <br />made based on results from the StateCU model, which is one of the components of the <br />Colorado's Decision Support Systems (CDSS). <br />Some of the West Slope roundtable members pointed out there are differences <br />between consumptive use values as reported by the CDSS versus the Bureau of <br />Reclamation Colorado River Consumptive Uses and Losses Report. The Bureau's <br />consumptive use numbers are higher than those from CDSS. The reasons for <br />differences between the estimates of consumptive use as reported by the CDSS and <br />the Bureau of Reclamation in their respective Colorado River Consumptive Use and <br />Losses reports have been identified. The Bureau has been reporting consumptive use <br />values that are very close to potential consumptive use, apparently due to errors in <br />their shortage calculations. In addition, the Bureau's estimates of incidental losses <br />related to irrigation are higher than the CWCB feels are justified. Correcting these <br />inconsistencies results in estimates similar to those from CDSS. <br />The difference between the Irrigation Water Requirement (IWR) and Water Supply <br />Limited (WSL) calculations of consumptive use from State CU was raised in several <br />roundtable meetings. The IWR represents the maximum potential consumptive use of <br />irrigation water exclusive of precipitation. The WSL is the calculation of actual <br />consumptive use based on the seasonal availability of water, water rights and <br />irrigation practices. Results for both IWR and WSL will be included in future <br />reporting of agricultural demands. <br />Arkansas basin agricultural demands have been derived from the HI Model and <br />information provided by CWCB and DWR staff and the USGS. Estimates of <br />agricultural demands in the South and North Platte basins will be derived from <br />information from the Division of Water Resources and preliminary work on the South <br />Platte DSS. There was a discussion at the last South Platte roundtable on how to <br />handle the agricultural lands irrigated with alluvial groundwater that have recently <br />been taken out of irrigation as a result of Senate Bi1173. The Division 1 Engineer <br />estimates that approximately 800 to 1,000 out of the 5,000 irrigation wells have been or <br />will be shut down due to the lack of augmentation water. It is proposed that <br />approximately 60,000 acres remain in the baseline estimate of irrigated acres since <br />they have been historically irrigated. Some roundtable members expressed the <br />opinion that the lands irrigated with groundwater as their sole source of irrigation <br />water will not be irrigated in the long term due to the inability to afford the <br />augmentation water. The 2030 agricultural demand forecast is proposed to include <br />A <br />D RAFT <br />C:\DOCUments and Settings\rb3.DWRVv1y Documents\SWSI\rblfnalDemand Forecasts memo to CWCB 3-17-04 meeUng-revisetl_apm.doc