About the data
Every figure on this site comes from 208,243 well construction records published by the Idaho Department of Water Resources, retrieved 2026-09-29. Nothing is modelled, interpolated or estimated unless it carries an estimate badge and shows its method.
Where the records come from
Idaho drillers are required to file a construction report for every well they complete. IDWR publishes those reports, including total depth, depth to water, reported yield, well type and construction date. We query them by radius around a point, and recompute county statistics from the full set.
Coverage is most complete from July 1987 onward. Earlier wells are patchy and some were never reported at all, so any answer to "how deep are wells here" is really "how deep were the wells somebody reported here". That is good evidence, not a census.
What we never show
IDWR well logs can include the property owner's name and address. We never display, export or retain those fields. Only technical values — depth, water level, yield, dates, well type and distance — reach any page or report.
How complete is each field?
Not every record reports every value, so every statistic we publish carries the count behind it. Across all 208,243 Idaho records:
| Field | Records reporting it | Share |
|---|---|---|
| Total depth | 141,748 | 68.1% |
| Depth to water | 186,880 | 89.7% |
| Reported yield | 123,761 | 59.4% |
Values we deliberately exclude
Government datasets use magic numbers, and rendering one makes a product look broken or, worse, quietly wrong. Four cases are filtered, each for a stated reason:
- Construction dates of 9999-12-31 appear on about 4.8% of records and mean "not reported". Years outside 1900 to next year are treated as absent rather than printed.
- A static water level or yield of exactly 0 is ambiguous: it can mean an artesian well, or that nobody wrote a figure down. We exclude zeros and disclose how many we excluded. This matters — on one lookup it moved a median from 12 ft to 29 ft.
- Depths under 18 ft are data-entry errors, not wells. Idaho's own definition of a well requiring a permit is an excavation deeper than 18 ft. Twenty-two records statewide fall below it, and they were setting the minimum on every county page.
- FEMA base flood elevations of -9999 mean "not applicable", not an elevation below sea level.
Why we publish percentiles, not extremes
County pages report the 10th to 90th percentile rather than the outright minimum and maximum. A single mistyped record distorts a range: one 1997 Canyon County log reports 15,187 gallons per minute, where the next highest is 80 — almost certainly a daily total typed into a per-minute field. One bad record should not define a county.
Medians vary enormously across Idaho — 66 ft in Lemhi County up to 380 ft in Kootenai County. A statewide average would hide exactly the variation that decides your drilling bill.
How accurate are the locations?
Only 22.9% of Idaho well locations are GPS-derived. 59% were placed from a quarter-quarter section description — a 40-acre block — so an individual coordinate can be roughly 900 feet from the real well. We round distances to a tenth of a mile and label every row with how it was located. Wells placed from a section description share a centroid, which is why map markers genuinely overlap.
Where numbers stop being evidence
Cost figures are the one place we publish something that is not a record. A cost line appears only when it has both a range and a named source, and it is badgedestimate when the figure is a published statewide number rather than a quote obtained in that county. Today every published cost line is a statewide estimate. Drilling cost estimates show their method: a median depth, a record count, and a per-foot rate, multiplied.
We also distinguish "source unavailable" from "source checked, found nothing". An outage must never read as an all-clear.
How often it refreshes
County statistics were last recomputed on 2026-09-29. Live lookups query IDWR directly and cache the response, so a lookup reflects the state's records at the time you run it rather than the date above. Rarely-changing layers — nitrate priority areas, flood zones — are cached longer; each report lists every source with its own retrieval date.
Use the data yourself
County statistics are published as a machine-readable file with the caveats attached, so anyone quoting the numbers gets the limits in the same payload.
/api/county-stats.json — all 44 counties, with record counts, medians, percentiles, health districts and source attribution.
The underlying records are public. Well construction reports come from the Idaho Department of Water Resources; soils from USDA NRCS; flood zones from FEMA; nitrate priority areas from Idaho DEQ, published through IDWR. Found something wrong? Tell us — corrections to our handling are welcome, and we will say what changed.