Lessons Learned in Northern Illinois

Transcription

1 Lessons Learned in Northern Illinois USING DATA TO IMPROVE OUR UNDERSTANDING OF GROUNDWATER FLOW DEVIN MANNIX, ISWS

2 ISWS Groundwater Data Collection (an abridged primer) Illinois Water Inventory Program (IWIP) water withdrawals, groundwater levels for high capacity users throughout the state, including municipal supplies, industries, irrigation, etc. Well construction reports and ISWS wells database well completion data, sealing dates, casing information, aquifers, water levels, etc. Observation well network discrete (hand measurements) and continuous water level data for dozens of wells around the state Synoptic measurements Large scale (200+) water level measurements over a short time period, typically conducted every five to seven years for the sandstone aquifers, and for individual projects Throughout the talk data sources will be highlighted here

3 Geology of Northern Illinois

4 Recharge Areas to Sandstone Aquifers

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6 1980 Present Data source: ISWS synoptic measurements, IWIP water levels, reported well completion data

7 St. Peter Ironton-Galesville Data source: ISWS synoptic measurements, IWIP water levels, reported well completion data

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9 Multi-Aquifer Wells

10 Single Aquifer Well (Ironton-Galesville)

11 Historical sandstone pumpage: A tale of two cones Data Source: IWIP Groundwater withdrawals, facility reporting (pre-1980), ISWS Wells database

12 Preliminary model results* (2050) Baseline projected demands No increase in demands, more pumpage shifted to Ironton-Galesville Baseline projected demands + pumpage shifted to Ironton- Galesville

13 *However, these simulations don t necessarily account for increasing shallow aquifer connections that may be mitigating impacts to the sandstone. Are we saved?

14 Domestic wells In recent years, more residential users have been drilling private wells into the St. Peter Sandstone Shallow aquifers may have limited areas of productivity Improperly cased St. Peter wells have caused nearby wells in the shallow bedrock to run dry Creates a feedback where increasing artificial recharge to the sandstone aquifers comes at the expense of shallower aquifers, requiring nearby domestic users to tap into the sandstone

15 Galena-Platteville Wells Kane, Kendall, and Will Counties Data Source: ISWS wells database, well construction reporting

16 Data Source: ISWS wells database, well construction reporting

17 Small capacity wells at greatest risk of going dry Per 1246 small supply wells open to the St. Peter sandstone in Kendall and Will Counties Most domestic wells are completed only in the upper portion of the aquifer, requiring deepening even with modest desaturation Data Source: ISWS wells database, well construction reporting

18 Proliferation of domestic wells Data Source: ISWS wells database, well construction reporting

19 Pathways for Artificial Recharge to Sandstone Data Source: ISWS wells database, well construction reporting

20 Estimated Artificial Recharge: < 5 MGD (3% of sandstone Q) 16.7 MGD (25% of sandstone Q)

21 Artificial recharge: a holistic viewpoint Though this artificial recharge is a boon to the sandstone aquifers, wells that are properly constructed are at the mercy of sandstone withdrawals The magnitude and long term viability of this artificial recharge remains in question Primarily water removed from storage? How long before subdivisions need alternate water sources and seal off existing wells? Are we saved?

22 Where does that leave us? Data Source: ISWS synoptic measurements, facility records

23 Where does that leave us? Heads have continued to decline in spite of additional recharge from shallower aquifers Though many strategies can be employed to extend the life of the aquifers (drilling more MAWs, increasing shallow connections, etc.), none are likely to offer a sustainable solution, while also having negative implications for residential users

24 Final words Many of these insights have been gained not through simulations or extensive studies, but through data collection and examining existing records Maintaining good working relationships with communities and industries, and encouraging regular data collection and open data exchange, must remain a priority These trends may have gone unnoticed if not for the extensive records already established, but there is additional work to be done and many more questions to be answered

25 Questions? Clipart shamelessly borrowed from: