Artifical Recharge of Ground Water in Colorado

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Artificial Recharge of Ground Water in Colorado A Statewide Assessment A progress report was prepared in 1960 addressing artificial recharge at Olds Reservoir and Kiowa Creek (CSU, 1960). Application of artificial recharge in Colorado blossomed in the 1980s following the drought of 1977 as farmers in the South Platte River Basin and the San Luis Valley realized that artificial recharge could be used to restore water levels in the near - surface aquifers as well as to manage timing of available surface -water supplies with high demands during crop growing seasons. Recently, artificial recharge is being developed in the Denver Basin by several municipal water districts for long -term storage. An in -depth discussion of artificial recharge projects in Colorado is presented in Section VI. II. Definitions of Recharge The original source of ground water is precipitation (rain, hail, or snow). Natural recharge occurs when precipitation percolates into the ground and reaches the water table. Natural recharge rates in Colorado are highly variable, with only 0 -12 percent of precipitation contributing to recharge of long -term ground -water storage. Enhanced recharge has historically consisted of vegetation management, where deep- rooted, water - loving vegetation is replaced by shallow- rooted water - conserving vegetation or bare soil. Enhanced recharge can also be achieved by routing storm -water runoff from urban areas to designed infiltration facilities. Induced recharge is created by the pumping of alluvial wells adjacent to streams and rivers. Decreased water tables around the wells increase flow to the alluvial aquifer through the riverbed and stream banks. Incidental recharge is the unintentional recharge of ground water including return flows from septic -tank leach fields and deep percolation from irrigation. The reduction in evapotranspiration and increased runoff resulting from urbanization (more land surface covered by impermeable materials) may also be considered incidental recharge in circumstances where that water flows to natural surfaces or ephemeral streams. Various types of recharge and underground water storage are illustrated in Figure 11 -1. Artificial recharge, aquifer storage and recovery, and underground water storage are terms that are central to the topics of this study. The definitions of these terms as used in this report are: Artificial Recharge (AR): Engineered or designed systems that put water on, or in, the ground for the purpose of infiltration and subsequent migration to underlying aquifers to augment ground -water resources. (the term "artificial" implies a mechanism other than natural meteoric ground -water formation) Aquifer Storage and Recovery (ASR): ASR is a type of artificial recharge that focuses on the use of injection/pumping well systems to inject water directly into the receiving aquifer for future recovery at the same location. Underground Water Storage: The storage of water beneath the ground surface in large caverns, voids, or mines in which hydraulic control can be maintained.