Hydrohistorian
CHAPMAN
Monitored well · 150654 · Division 2 · Water District 17
Its well permit here · Well permit at DWR ↗
Source DWR administrative record · verify at DWR well record ↗ Source DWR administrative record · verify at DWR permit record ↗
Unclassified
No aquifer or designated-basin assignment — administrative world unknown, kept out of recharge math.
Water-level record
No water-level measurements are cached for this well. It is in the well inventory — permit, construction and aquifer below — but nobody has logged a level we hold.
Geophysical log
DWR holds a geophysical log for this well, run 2016-04-14 (gamma, resistivity, spontaneous_potential). DWR's log page.
Formation picks (DWR)
| Aquifer | Top ft | Base ft | Net sand ft |
|---|---|---|---|
| ARAPAHOE | 77 | 262 | 25 |
| LARAMIE-FOX HILLS | 378 | 135 | |
| ALLUVIAL | 77 |
Net sand is DWR's own reading of the log (its gLogThickness), not the gross interval.
Net sand per aquifer, from the gamma curve
Computed here from DWR's own digital log (LAS): linear gamma index, clean/shale lines at p10/p90 of the gamma over the interval, sand where Vsh < 0.4, beds under 1.0 ft merged. DWR’s own pick is beside it, never averaged with it.
| Aquifer | Interval ft | Net sand ft | Net / gross | DWR net sand ft | Difference ft |
|---|---|---|---|---|---|
| ARAPAHOE | 77–262 | 67 | 0.36 | 25 | +42 |
A gamma cutoff is a convention, not a measurement. Against DWR’s own picks on 50 wells this one correlates at r 0.86 with a median error near 30% and no bias (how it was scored).
Curves digitized from the scan
Hydrohistorian traced the scanned log automatically. 1 curve passed the confidence gate; 15 did not and are listed with the reason. Screening data: the scan stays the record.
| Curve | Interval ft | Coverage | Verdict | Curves like this one scored | |
|---|---|---|---|---|---|
| 64" Normal Resistivity (Ohm-m) | -3–593 | 89% | not used: ambiguous rows 89%; curve class not verified by the benchmark: 64" Normal Resistivity traced as thin | ||
| Natural Gamma (CPS) | -3–593 | 97% | pass | r 0.99 median, error 3.3% of scale, 3% below r 0.8 (n 89) | LAS |
| Single-Point Resistance (Ohm-m) | -3–593 | 87% | not used: curve class not verified by the benchmark: Single-Point Resistance traced as thick | ||
| Spontaneous Potential (mV) | -3–593 | 80% | not used: SP: the printed scale is a span with an unknown offset, and the benchmark could not verify the shape (median r 0.28 after offset removal) | ||
| CPS (CPS) | 0–159 | 100% | not used: ambiguous rows 65%; curve name not recognized: 'CPS' | ||
| Ohm-m (Ohm-m) | 0–159 | 66% | not used: ambiguous rows 76%; curve name not recognized: 'Ohm-m' | ||
| mV (mV) | 0–159 | 0% | not used: coverage 0%; curve name not recognized: 'mV' | ||
| ohm (ohm) | 0–159 | 60% | not used: curve name not recognized: 'ohm' | ||
| CPS (CPS) | 180–379 | 100% | not used: ambiguous rows 86%; curve name not recognized: 'CPS' | ||
| Ohm-m (Ohm-m) | 180–379 | 100% | not used: ambiguous rows 40%; curve name not recognized: 'Ohm-m' | ||
| mV (mV) | 180–379 | 0% | not used: coverage 0%; curve name not recognized: 'mV' | ||
| ohm (ohm) | 180–379 | 88% | not used: curve name not recognized: 'ohm' | ||
| CPS (CPS) | 400–593 | 94% | not used: ambiguous rows 64%; curve name not recognized: 'CPS' | ||
| Ohm-m (Ohm-m) | 400–593 | 99% | not used: ambiguous rows 54%; curve name not recognized: 'Ohm-m' | ||
| mV (mV) | 400–593 | 3% | not used: coverage 4%; ambiguous rows 41%; curve name not recognized: 'mV' | ||
| ohm (ohm) | 400–593 | 87% | not used: curve name not recognized: 'ohm' |
"Curves like this one" is the benchmark row for this curve's class: curves of the same name traced the same way, scored against DWR's own digital log of the same run. r is correlation (the print's own smoothing allowed for); error is mean absolute error as a share of the track's printed range; "below r 0.8" is the share of passing curves in the class that still disagreed with DWR's log, which this curve's own numbers cannot rule out.
The LAS files and every verdict are in the statewide groundwater release
(/data, table gw_digitized); the MCP server's gw_digitized_curves and
gw_net_sand work from them. How well the tracer does was
measured against DWR's own digital logs.
The well itself
| Total depth | 579.0 ft |
|---|---|
| Perforated interval | 408.0–558.0 ft |
| Ground elevation | 6100.0 ft |
| Permit | 79744 |
| Location | 38.79000, -104.25000 |
What this page is not
Monitoring records are irregular: measurements cluster where somebody chose to look, so a trend describes this well's record, not the aquifer as a whole. Levels are DWR's published measurements, unedited. A trend here is not a prediction, and it is not a determination about anyone's water right.