C150402 CT2015-090 Feasibility Study

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Although the Ephraim system is entitled to water from either the North Branch or the Main Stem of the Conejos River, the core has virtually disappeared, causing Ephraim irrigators to only be able to get water from the main stem of the Conejos. In this critical area, the Ephraim Ditch Company's core has essentially been washed away over time (see photo), contributing to decades of limited diversion to irrigators and potential over- payment to the Compact. This project, combined as described below, seeks to ameliorate and perhaps eliminate that problem. Groundwater Dependence: Ephraim Ditch Company owns five communal wells which were drilled into the confined aquifer starting in the 1950s. These wells pump water directly into the system's ditches in response to wherever the greatest need exists. Like other ditches in the Confluence area, these wells pump into Ephraim's communal system. Parcels in the Ephraim system use flood and sprinkler irrigation, with sprinklers fed by surface water as well as ground water. Due to extreme and prolonged drought conditions, and despite the uniqueness of this shared system, irrigators have great difficulty getting their surface water in priority. This causes water users, by necessity, to depend excessively on pumping from the communal wells, thus potentially causing further drawdown on the already critical levels of the Rio Grande Basin aquifers. With its century old core completely washed away and the deteriorated condition of its headgate, Ephraim Ditch has steadily increased its dependence on ground water. With priority 56, if irrigators were able to get their water in priority they would reduce their dependence on pumping. An important objective of this project is to reduce dependence upon ground water by efficiently delivering and managing surface flows. As described below, the Conejos Water Conservancy District (the District) is assisting this project in order to extend its Whole River Strategy to an additional 5,000 acres served by the Ephraim Ditch system and to avoid over-paying Colorado's obligation to the Rio Grande Compact. The Conejos Water Conservancy District's interests in this project are 1) to reduce the need for excessive use of well pumping, which potentially further stresses the Rio Grande Basin's aquifers. The majority of the ditches in the area of The Confluence are forced to pump because they cannot otherwise get their water; 2) to extend the District's "whole river strategy" throughout the Conejos River system in order to efficiently manage Rio Grande Compact entitled waters; 3) to assist small ditch companies in the critical area just upstream from the Colorado- New Mexico border to upgrade the structures, install the infrastructure, and employ the most effective water-management technologies available; and -� Prepared by the Conejos Water Conservancy District, P.O. Box 550, Manassa,CO 81141 " Per contract: Nicole V.Langley,Transforma Research&Design(www.transformagrants.com)