Aquifer Recharge |
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Demonstration project will utilize flood irrigation in an attempt to recharge declining groundwater levels At the turn of the century, as the Teton Valley was settled, dramatic changes in the waterscape took place. Early pioneers recognized the water wealth running out of the Teton and Big Hole Mountain Ranges and set about making it usable. In order to make agriculture viable, the quick flush of spring runoff needed to be contained and the water stored for use later in the season. In other basins in Eastern Idaho this was done by building storage reservoirs; however, in the Upper Teton Basin the geologic setting didn’t permit construction of a dam. Instead, the practice of flood irrigating farmland with generous amounts of early spring runoff was instituted and a large natural underground storage reservoir resulted. An extensive system of canals and ditches was built to deliver water to cultivated fields and water was turned out onto those fields as it reached the valley floor. The changes that occurred in the hydrology of the Teton Valley were remarkable. Tributary streams no longer carried large amounts of water to the Teton River in the springtime; this water was dispersed into the canal system and into the ground. The flood peak for the Teton River was attenuated (spread out over time) and, just as interestingly, groundwater levels throughout the valley began to rise. Additionally, late summer flows in the Teton River were higher because water was released slowly from the aquifer into springs that feed the Teton River. The landscape also changed. On the eastern fringe of the Teton River, the flow in spring creeks increased and existing wetlands were augmented by the higher groundwater. This hydrologic setting persisted through much of the twentieth century. In the 1970s, however, irrigation technology advanced and farmers began to use sprinkler instead of flood irrigation, which enabled them to irrigate larger areas of ground with less water. Again, the hydrology of the basin changed but this time more slowly. Now, in 2003, as more land is taken out of agriculture and developed, and after five years of drought, we are just realizing how dramatic the effects of this second change in water use have been. Low flow days, below 150 c.f.s., on the Teton River have increased since 1980, spring creeks are declining, and wetland areas are decreasing. Foster Slough that used to transport boats is no longer easily navigable; ground where waders were once needed is now traversed in sneakers. Since Teton Valley natural reservoir is not being used as much as it was, groundwater levels are dropping. Boyd Moulton, Randy Berry, Lyle Kunz and others have long believed that replenishing groundwater—aquifer recharge—is a critical component of restoring the health of Teton Valley’s fisheries and wetlands. FTR is currently working with them, and a growing group of farmers, to reintroduce aquifer recharge to areas of the valley where it is still feasible. We have had a series of meetings with farmers and ranchers to discuss recharge and related water rights. Attendance at these meetings has been excellent and discussions candid and productive. Dr. Michael Nicklin, the groundwater hydrologist from Bozeman who produced the original Teton Basin aquifer model, has played a critical role in the process. He has spent countless hours talking with irrigators and FTR staff and visiting potential recharge sites. Equally importantly, he has generously attended community meetings and made presentations about his work. He has put together a recharge demonstration project and monitoring plan that will be implemented in the spring of 2004. The project includes flood irrigation in the Fox Creek area and a gravel pit recharge effort near Trail Creek. We at FTR are very excited to be participating in a project that we believe will start to provide solutions to problems that are occurring has a result of declining groundwater levels in the Teton Basin. We greatly appreciate the time and effort that so many stakeholders have taken to discuss these issues and look forward to continuing the dialogue.
Groundwater - Aquifer Recharge Project Report Because of the large file size, the report is split into the sections below for downloading.
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