Farmer City IL Well Data & Aquifer Code 0101 Explained

Reviewed September 2026 against the Illinois EPA Source Water Assessment Program, the Illinois State Geological Survey Clearinghouse, and the Illinois State Water Survey.

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Farmer City, Illinois draws its public water supply from wells completed in aquifer code 0101 — the sand-and-gravel aquifer classification used statewide by the Illinois State Geological Survey (ISGS). The city’s Illinois EPA Source Water Assessment Program (SWAP) factsheet lists individual well depths, the shared aquifer code, and a description of the aquifer material as “sand and gravel.” Below, we walk through what each field in that table means, what the depth and yield numbers imply for a small Midwestern municipal system, and how to pull the current version yourself rather than trust a screenshot that may already be out of date.

What This Page Covers

The SWAP Factsheet: What Farmer City’s Table Actually Shows

The Safe Drinking Water Act amendments of 1996 (42 U.S.C. § 300j-13) required every state to stand up a Source Water Assessment Program. Illinois EPA implemented that mandate as the Illinois EPA Source Water Assessment Program, which produces a one- or two-page factsheet for every public water supply in the state, including Farmer City’s. The factsheet is not a marketing document — it is a compliance artifact, and its well data table is the part most searchers are actually trying to read.

A typical SWAP factsheet well table carries four columns that map directly onto the queries this page is built to answer:

• Well # — the utility’s internal identifier for each active production well.
• Depth — total drilled depth in feet, measured from ground surface to well bottom.
• Aquifer — the ISGS aquifer code the well draws from; for Farmer City, this is code 0101.
• Description — the geologic material at the producing zone, listed for Farmer City as “sand and gravel,” sometimes rendered “active well” alongside the material description.

For Farmer City specifically, Illinois EPA SWAP documentation puts the maximum documented well depth at 200 feet, drawing from the sand-and-gravel unit under aquifer code 0101. If your search brought you here looking for the exact per-well breakdown (Well #2, #9, #10, #11 depths individually), that level of granularity is not published in any source available for this review — see the verification section below for how to request the underlying factsheet PDF directly from Illinois EPA or the city.
Readers who want the source assessment itself can review what the Illinois EPA SWAP shows for the town’s wells.

Aquifer Code 0101: Sand & Gravel, Decoded

Aquifer classification codes in Illinois come from the ISGS, and code 0101 designates the major sand and gravel aquifer category — unconsolidated glacial outwash deposits that yield groundwater through pore space between sand and gravel grains, as opposed to fractured bedrock aquifers, which carry different two- and three-digit codes. This is the same classification system referenced across every SWAP factsheet in the state, which is why “aquifer code 0101” and “sand and gravel” appear together on Farmer City’s sheet and on hundreds of others statewide.

Per the Illinois State Geological Survey Clearinghouse, major sand-and-gravel aquifers statewide are defined by three current standards:

• Minimum yield capacity: 70 gallons per minute (GPM) to qualify as a “major” aquifer under ISGS classification.
• Typical top depth: 300 feet below ground surface.
• Typical base depth: 500 feet below ground surface.
• Potable water threshold: total dissolved solids (TDS) at or below 2,500 mg/L.

Farmer City’s documented maximum well depth of 200 feet sits shallower than the statewide typical top-of-aquifer depth of 300 feet. That is not an error in the factsheet — DeWitt County’s glacial outwash deposits are not uniform in depth across the state, and a well can fully penetrate a locally shallow sand-and-gravel lens well above the statewide typical range. What the published sources do not include is a DeWitt-County-specific isopach (thickness) map or a confirmed recharge rate for this particular lens; that is listed plainly in the gaps below rather than estimated.

Well Depth Data: Reading the Numbers Correctly

When a SWAP factsheet lists “depth,” it means the total drilled depth of the well casing, not the depth to the water table and not the aquifer’s own top-to-base range. These are three different numbers people conflate:

1. Well depth (Farmer City: up to 200 feet) — how deep the well itself was drilled.
2. Aquifer top depth (statewide typical: 300 feet) — where the sand-and-gravel unit typically begins.
3. Aquifer base depth (statewide typical: 500 feet) — where the unit typically ends.

Because Farmer City’s wells terminate well above the statewide typical aquifer top, the local sand-and-gravel lens is evidently shallower than the regional norm — consistent with the kind of localized glacial outwash pocket common across central Illinois. A hydrogeologist confirming this for a specific parcel would want the confining-layer thickness (clay/till separating the producing zone from the surface) and the aquifer’s lateral extent, both of which are listed under Gaps below because no current published figure covers them for this specific well field.

On yield: the 70 GPM minimum is a classification threshold, not a guarantee of what any individual Farmer City well produces. No source reviewed here publishes per-well GPM figures for Farmer City’s active wells. If you need that number for engineering or investment purposes, request it directly — see the verification section.

Farmer City vs. Statewide Sand & Gravel Standards

The table below is the structured comparison an AI answer box will not assemble for you, because it requires cross-referencing two separate ISGS/EPA data sets rather than summarizing one page.

Contamination Source Inventory & Compliance History

Part of what a SWAP factsheet does beyond listing well depth is inventory the potential contamination hazards within the assessment area around each wellhead — old fuel tanks, agrichemical storage, septic fields, and similar land uses that a state hydrogeologist flags during the source-water delineation survey. For Farmer City, that 1989 survey documented 10 potential groundwater contamination hazards near the city’s wells, per Illinois EPA’s SWAP records. Listing a source does not mean it has caused contamination — it means the location sits close enough to the wellhead protection area to warrant tracking.
A closer reading of the full document, including its depth and aquifer entries, appears in what Farmer City’s SWAP factsheet shows.

On actual water quality outcomes, the City of Farmer City’s Consumer Confidence Reports (CCRs) — published annually and archived on the City of Farmer City Water Department site — show zero EPA maximum contaminant level (MCL) violations from 2010 through the most recent report on file. That is a 15-year-plus clean compliance record for a system drawing from a sand-and-gravel aquifer shallower than the statewide typical range, which is itself informative: shallow aquifers are generally more vulnerable to surface contamination than deep confined ones, so a sustained zero-violation record says something about either the confining layer thickness or the effectiveness of the wellhead protection measures tied to that 1989 source inventory. Neither the confining-layer thickness nor a residence-time (age-dating) study for Farmer City’s groundwater is published in the sources reviewed here — both are listed under Gaps.

Statewide, groundwater is not a minor supply source: roughly 60% of Illinois’ rural water supply depends on groundwater, according to Illinois State Water Survey (ISWS) and USGS resources, which is the broader reason SWAP factsheets like Farmer City’s exist at all — small systems drawing from shallow sand-and-gravel lenses are exactly the case the 1996 federal mandate was written for.

How Illinois Monitors Groundwater Statewide

Farmer City’s factsheet is one entry in a much larger monitoring apparatus. The Illinois State Water Survey Groundwater Monitoring Networks program maintains 370-plus wells statewide as its long-term monitoring backbone, with some station records running back to the 1950s. That statewide count is useful context for scale, but it is not a Farmer City-specific figure — DeWitt County’s share of that network, if any wells there are part of it, is not broken out in the sources reviewed for this article.

For a sense of what a focused regional study looks like, the U.S. Geological Survey’s 2020 water-quality investigation of sand-and-gravel aquifers in McHenry County sampled 41 monitored wells, documented in USGS Scientific Investigations Report 2022-5110. McHenry County is a different aquifer system from DeWitt County’s, so its specific water-quality numbers do not transfer to Farmer City — but the study’s methodology (well selection, sampling protocol, parameter list) is a reasonable template for what a DeWitt-County-specific study would need to cover if one is ever commissioned. No equivalent published study exists yet for the Farmer City well field specifically.

How to Verify or Refresh This Data Yourself

Every figure on this page has a shelf life, and the durable value here is the method for checking it rather than the numbers themselves. Use this checklist:

• For the aquifer classification and yield/depth standards: the ISGS Clearinghouse updates its aquifer layer periodically. Search “Illinois aquifer yield definitions” directly on clearinghouse.isgs.illinois.edu for the current classification criteria rather than assuming the 70 GPM / 300–500 ft figures cited above never change.
• For current well counts and levels tied to aquifer code 0101 or the Farmer City township: the USGS National Ground-Water Monitoring Network (NGWMN) database at usgs.gov/apps/ngwmn updates daily and can be queried by aquifer code or location.
• For Farmer City’s own compliance record: the city publishes its Consumer Confidence Report annually, due by June 30 each year, at cityoffarmercity.org. The Illinois EPA SWAP public-facing map also carries the underlying factsheet PDF if you need the original document rather than a summary.
• For the exact per-well depth and GPM breakdown not itemized in public summaries, request the full SWAP factsheet PDF from Illinois EPA’s Bureau of Water or contact Farmer City’s water department directly — this is the most reliable route to the individual Well #2/#9/#10/#11 figures that current published sources do not break out.

Why Farmonaut Cares About Subsurface Data

Reading a well-depth table correctly — separating drilled depth from aquifer top/base, treating a classification code as a category rather than a guarantee, and knowing which numbers are simply not published yet — is the same discipline that applies to subsurface mineral characterization. Farmonaut’s satellite-based platforms serve exploration teams working through comparable questions about what lies beneath a survey area before committing to ground-truth drilling.

Two Farmonaut resources cover that adjacent ground in more depth: our overview of gold companies in USA and their exploration approaches, and our breakdown of mining companies in US and the technologies they deploy. For the exploration side specifically, our satellite-based mineral detection platform matches spectral signatures from multispectral and hyperspectral imagery to likely mineral zones, reducing the amount of exploratory ground disturbance before a drilling decision is made — the same “characterize before you commit” logic that a hydrogeologist applies when reading a SWAP factsheet before permitting a new well.

For a deeper look at how that subsurface-mapping approach scales to full 3D targeting, our satellite-driven 3D mineral prospectivity mapping resource walks through drill-target-ready outputs delivered within days rather than the months a purely ground-based survey program takes.

Mining Sector Context: Copper and Gold Innovation in the USA

The same satellite and remote-sensing toolkit used to characterize aquifer-adjacent geology also underpins exploration for strategic minerals across the United States. Freeport-McMoRan Inc. operates flagship copper mines in Arizona (Morenci, Safford), New Mexico (Chino), and Utah, and is investing heavily in automated mining equipment and real-time data monitoring. Asarco LLC runs the Ray, Mission, and Hayden complexes in Arizona with a focus on water management and reduced carbon footprint. Hudbay Minerals is expanding exploration using real-time ore-body sensing across North America.

On the gold side, Newmont Corporation, Barrick, and Kinross Gold lead US production, concentrated primarily in Nevada, applying chemical-free recovery methods, remote equipment operations, and closed-loop cyanide systems respectively. Coeur Mining Inc. combines gold and silver production with advanced satellite exploration and predictive resource modeling.

Frequently Asked Questions

Conclusion

Farmer City’s SWAP factsheet is a compliance document built on a statewide classification system: aquifer code 0101 marks it as drawing from sand-and-gravel deposits, its documented well depth tops out at 200 feet against a statewide typical range of 300–500 feet, and its compliance record shows zero MCL violations since 2010. The numbers that are not yet published — per-well GPM, confining-layer thickness, recharge rate, and groundwater residence time — are gaps you can close directly through Illinois EPA, the USGS NGWMN database, or the city’s own water department, using the checklist above.

For the mineral-exploration side of subsurface characterization, see how satellite-based mineral detection applies comparable principles to copper and gold targeting, or review our profiles of gold companies in USA and mining companies in US for the broader industry context.