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  • Operation of the rain gauge and groundwater monitoring networks for the Imperial Valley Water Authority, Year Eleven: September 2002 - August 2003.


  • 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. The ISWS also established a network of groundwater observation wells in the Mason-Tazewell area in 1994 that is monitored by the IVWA. The purpose of the rain gauge network and the groundwater observation well network is to collect long-term data to determine the impact of groundwater withdrawals in dry periods and during the growing season, and the rate at which the aquifer recharges. This report presents data accumulated from both networks since their inception through August 2003. Precipitation is recorded continuously at 20 rain gauges. Groundwater levels are measured the first of each month at 13 observation wells. The database from these networks consists of 11 years of precipitation data and nine years of groundwater observations. For the period September 2002-August 2003, the network received an average of 30.06 inches of precipitation, 5.84 inches lower than the network 10-year 1992-2002 average precipitation. Precipitation was below average in the fall, winter, and spring, but above average during the summer of 2003. In 2002-2003, groundwater levels in many wells tended to follow the now-familiar pattern of rising water levels in early spring and peaks in mid-summer before evapotranspiration demands cause water levels to decline. However, the extremely low precipitation that occurred from the period September 2002 through May 2003 (9.23 inches below the 11-year normal) caused a weak recovery before the irrigation season started. Several wells (MTOW-4, -10, -11, and -13) experienced essentially no water-level recovery during this reporting period. Water levels in MTOW-13, in particular, fell throughout the year. That well is located in northeastern Mason County, the area of lowest precipitation. Total irrigation for the June-September period was estimated to be 46 billion gallons (bg), the fourth highest total since monitoring began in 1995 and ranked just after the 47 bg in both 2001 and 2002. This can be attributed, in part, to the growth of irrigation systems in the Imperial Valley, which now has 1,867 systems. To improve our understanding of the relationship between groundwater, stream discharge, and irrigation, an irrigation test site was initiated in April 2003. Nine observation wells were installed in close proximity to an irrigated field that abuts Crane Creek. Transducers with data loggers were installed in two wells in June 2003 to monitor groundwater levels and in Crane Creek to monitor stream stage. Preliminary data are presented.

Originally Deposited as: 999999994457

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Language(s): EN-English

Volume or Year: 2005
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Date Created: 9 15 2005
Date Last Modified: 9 15 2005

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1. Operation of the rain gauge and groundwater monitoring networks for the Imperial Valley Water Authority, Year Eleven: September 2002 - August 2003. (20061003185059_ISWSCR2005-06.pdf).
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