WSP12980 - Laserfiche WebLink

Home Browse Search

I I I I I I I I I I I I I I I I I I I IV.A.3c Mid-Lateral In-Line Reservoirs The mid-lateral reservoirs would serve primarily to reduce lateral operational discharges and possibly reduce tailwater. These reservoirs would be constructed one-half to two-thirds of the way down the lateral and would have approximately 30 acre-feet of storage area. The reservoir would be constructed parallel and adjacent to the channel, or formed within an existing lateral by widening and deepening a section of the channel to serve as a collector pool. This would allow excess flows to be stored within the lateral and used to supply deliveries downstream. Mid- lateral reservoirs would also function to reduce lateral fluctuations and increase delivery reliability. From 1987 to 1992, the District's average annual lateral discharge averaged 115,227 acre-feet. (On-Farm Irrigation Efficiency, Boyle Engineering, 1993) The Plum-Oasis lateral interceptor project is estimated to have conserved 6,420 acre-feet. The Mulberry-D and Trifolium interceptors are estimated to save 15,000 and 17,200 acre-feet, respectively. Thus, an estimated 38,620 acre-feet of this discharge will have already been conserved, leaving approximately 77,000 acre-feet of losses available for further conservation. lID has no experience with mid- lateral reservoirs, therefore water conservation is unknown. However, an analysis of lID delivery records for selected laterals indicates that 60 percent of lateral discharge might be conserved. One way to improve this estimate is to build a mid-lateral reservoir in a test program, similar to the initial test programs that evaluated 12-hour deliveries and tail water return systems. The construction of 135 mid-lateral reservoirs would be required to conserve the lateral discharge noted above, about half of which will have drop-leaf gate structures for gravity inflow and outflow. (Water Requirements and Availability, Parsons, 1985). Twelve years would be required to install the proposed reservoirs if one were constructed each month. If less than full District coverage is selected, careful planning will be required to select the most cost effective laterals. This project would require landowners to take land out of production, but in exchange would allow them the ability to turn water back to the lateral simply by notifying the District prior to their action. District operating rules would need to be modified for this project to allow the water users these cut-back opportunities and to defme the conditions under which they would Draft: Subject To Revision 12/21/95 36