The Illinois State Water Survey (ISWS), under contract to the Imperial Valley Water Authority (IVWA), has operated a network of rain gauges in Mason and Tazewell Counties since August 1992 and a network of groundwater observation wells since 1994. The purpose of the rain gauge and groundwater observation well networks is to collect long-term data to determine the impact of groundwater withdrawals during dry periods and during the growing season, and the rate at which the aquifer recharges. This letter serves as the year end report for Year 18 which covers the time period from September 1, 2009 through August 31, 2010. The groundwater observation well network consists of thirteen wells, MTOW-01 through MTOW-13. MTOW-01, located near Snicarte, Illinois, is an inactive, large diameter, hand-dug domestic well that has been monitored by the ISWS since 1958. This well is equipped with a Stevens, Type F water-level recorder that produces a continuous record of the groundwater level on a 32-day paper chart. In Year 15, a deeper well was drilled to replace MTOW-01 which we found would go dry during dry weather. This new well, named Snicarte #2 or MTOW-01a, has taken the place of the original well (MTOW-01 or Snicarte #1) within the monitoring well network. The two wells were being observed jointly so that their water level data can be correlated. The new well was first equipped with the same type of Stevens recorder as the original well, but has since been converted to digital data collection. This digital data collection system is outfitted with telemetry which allows access to the data at the ISWS office via a cell phone modem. The final correlation between data from the two Snicarte wells occurred during Year 18. A separate letter report will be presented in the future to address the Snicarte well correlation to the IVWA. The remaining observation wells are drilled wells between 2 and 6 inches in diameter. With the exception of MTOW-05 and MTOW-09, these wells are equipped with pressure transducers that electronically log the groundwater level data. In accordance with our agreement, each well, with the exception of MTOW-05 and MTOW-09, is visited by ISWS personnel during the first few days of the month during irrigation season and approximately bi-monthly during the non-irrigated portion of the year. MTOW-05 is measured by a local well watcher approximately monthly, while MTOW-09 is measured 3 or 4 times per year by an ISWS staff member.
|Original language||English (US)|
|State||Published - Mar 31 2011|
|Name||Imperial Valley Water Authority Annual Letter|