Hydrohistorian
Digitized geophysical logs
DWR holds scanned geophysical logs for 6,101 water wells, almost all in the Denver Basin. Hydrohistorian traces the scans into digital curve files (LAS) automatically, scores the tracer against DWR's own digital logs where both exist, and serves only what passed a gate set by that benchmark. Everything else is listed with the reason it did not.
What is served
730 curves on 178 wells passed the gate, out of
10,121 curves traced on 1,043 scans. Each well's page lists its curves with the
verdict and a download; the full table is gw_digitized in the statewide groundwater release.
| Curve class | Served | Benchmark n | median r | error, % of scale | within 2% | below r 0.8 |
|---|---|---|---|---|---|---|
| Gamma Ray (solid) | 568 | 411 | 0.988 | 0.6% | 98% | 7% |
| Natural Gamma (thick) | 90 | 89 | 0.991 | 3.3% | 40% | 3% |
| Single-Point Resistance (thin) | 54 | 49 | 0.994 | 0.6% | 96% | 6% |
| 64" Normal Resistivity (thick) | 7 | 11 | 0.997 | 0.3% | 99% | 9% |
| 16" Normal Resistivity (thick) | 7 | 13 | 0.858 | 4.8% | 45% | 23% |
| 16" Normal Resistivity (thin) | 4 | 6 | 0.960 | 1.2% | 90% | 0% |
How good the tracing is, and how we know
Measured on 402 wells (3704 scan pages) where DWR holds both the scan and its own digital LAS file: digitizer v2.4. Of 579 curves that passed the gate and have a truth curve, 41 (7%) still correlated below r 0.8 with DWR's log. Those are the gate's misses, and nothing in a curve's own numbers singles them out: every digitized curve is screening data; the scan stays the record.
- eff r: correlation with DWR's LAS, allowing for the smoothing the contractor applied to the print.
- median_error_pct_scale: mean absolute error as a share of the track's printed range, median over curves.
- share_below_r08: the class's curves that pass the gate but correlate below 0.8 with DWR's LAS: the gate's misses. Nothing in a curve's own metrics singles them out.
- The gate: at least 4 depth labels read on one straight axis (worst residual 1.0 ft), coverage at least 40%, at most 5% of rows carrying a second stroke of the same ink, scale numbers read at 0.8 confidence or better, a recognized curve name in a class the benchmark verified. Spontaneous potential never passes: its printed scale is a span with an unknown offset.
The full benchmark, with every curve class and the three gate variants that were measured and rejected: digitizer-benchmark.md; the table as a file: digitizer-quality.json.
What did not pass, and why
A traced curve can fail the gate for more than one reason; each reason is counted.
| Reason | Curves |
|---|---|
| ambiguous rows | 7,601 |
| curve name not recognized | 5,359 |
| dashed curve on a Phoenix/Pioneer print | 3,345 |
| coverage | 3,217 |
| solid curve on a Phoenix/Pioneer print | 2,351 |
| curve class not verified by the benchmark | 1,253 |
| scale OCR confidence | 739 |
| SP | 706 |
| calibration residual | 101 |
Scan pages the tracer could not read at all, in the benchmark set:
- 1056: no column of depth labels found
- 522: depth axis found but no scale header
- 151: load: that PDF page holds no scanned image
- 22: truth LAS unreadable: '4.00U'
- 18: truth LAS unreadable: 'No ~ sections found. Is this a LAS file?'
- 12: no horizontal grid below the header
- 3: crash: index 0 is out of bounds for axis 0 with size 0
- 2: truth LAS unreadable: ''
- 1: crash:
Not attempted, by design: 1980s-90s hand-filled strip charts (their scale is a typed sentence on a form, not a printed
header), the dashed curves of Phoenix/Pioneer prints, and their log-scale resistivities. Those scans are listed in
gw_documents with DWR's own link, and the MCP server's manual tracer (gw_digitize_log) reads one
page with a person's calibration.
Wells with a passing curve
| Well | Curves | Which |
|---|---|---|
| 149964 | 1 | Single-Point Resistance |
| 149965 | 1 | Single-Point Resistance |
| 149967 | 1 | Single-Point Resistance |
| 149971 | 1 | Single-Point Resistance |
| 149987 | 1 | Single-Point Resistance |
| 150403 | 1 | Single-Point Resistance |
| 150404 | 1 | Single-Point Resistance |
| 150406 | 1 | Single-Point Resistance |
| 150511 | 1 | Gamma Ray |
| 150584 | 1 | Gamma Ray |
| 150587 | 2 | Natural Gamma, Single-Point Resistance |
| 150590 | 1 | Natural Gamma |
| 150595 | 1 | Natural Gamma |
| 150611 | 1 | Gamma Ray |
| 150627 | 3 | 64" Normal Resistivity, Natural Gamma, Single-Point Resistance |
| 150628 | 1 | Single-Point Resistance |
| 150629 | 2 | 16" Normal Resistivity, Natural Gamma |
| 150638 | 1 | Natural Gamma |
| 150639 | 2 | Natural Gamma, Single-Point Resistance |
| 150640 | 1 | Single-Point Resistance |
| 150641 | 1 | Natural Gamma |
| 150642 | 1 | Natural Gamma |
| 150651 | 2 | Natural Gamma, Single-Point Resistance |
| 150653 | 2 | Natural Gamma, Single-Point Resistance |
| 150654 | 1 | Natural Gamma |
| 150655 | 1 | Natural Gamma |
| 150658 | 1 | Natural Gamma |
| 150659 | 2 | 64" Normal Resistivity, Natural Gamma |
| 150663 | 1 | 16" Normal Resistivity |
| 150734 | 1 | Natural Gamma |
| 150736 | 2 | Natural Gamma, Single-Point Resistance |
| 150738 | 2 | Natural Gamma, Single-Point Resistance |
| 150739 | 1 | Gamma Ray |
| 150975 | 1 | Single-Point Resistance |
| 151019 | 1 | Natural Gamma |
| 151020 | 2 | Natural Gamma, Single-Point Resistance |
| 151021 | 2 | Natural Gamma, Single-Point Resistance |
| 151022 | 1 | Natural Gamma |
| 151023 | 2 | Natural Gamma, Single-Point Resistance |
| 151027 | 1 | Natural Gamma |
| 151031 | 1 | 64" Normal Resistivity |
| 151040 | 1 | Natural Gamma |
| 151041 | 2 | Natural Gamma |
| 151046 | 2 | Gamma Ray |
| 151047 | 16 | Gamma Ray |
| 151061 | 4 | Natural Gamma, Single-Point Resistance |
| 151068 | 13 | Gamma Ray |
| 151087 | 10 | Gamma Ray |
| 151093 | 1 | Natural Gamma |
| 151094 | 1 | Single-Point Resistance |
| 151097 | 2 | Natural Gamma, Single-Point Resistance |
| 152103 | 2 | Natural Gamma, Single-Point Resistance |
| 152107 | 1 | Natural Gamma |
| 152118 | 2 | Natural Gamma, Single-Point Resistance |
| 152120 | 2 | Natural Gamma, Single-Point Resistance |
| 152121 | 2 | Natural Gamma, Single-Point Resistance |
| 152123 | 2 | 16" Normal Resistivity, Natural Gamma |
| 152124 | 3 | Natural Gamma, Single-Point Resistance |
| 152125 | 1 | Natural Gamma |
| 152126 | 1 | Single-Point Resistance |
| 152159 | 9 | Gamma Ray |
| 152166 | 1 | Natural Gamma |
| 152174 | 1 | Natural Gamma |
| 152271 | 6 | Gamma Ray |
| 152273 | 7 | Gamma Ray |
| 152296 | 2 | Natural Gamma, Single-Point Resistance |
| 152297 | 2 | 16" Normal Resistivity, Natural Gamma |
| 152298 | 2 | Natural Gamma, Single-Point Resistance |
| 152299 | 28 | Gamma Ray |
| 152308 | 12 | Gamma Ray |
| 152309 | 1 | Natural Gamma |
| 152310 | 1 | Natural Gamma |
| 152313 | 2 | Natural Gamma, Single-Point Resistance |
| 152321 | 23 | Gamma Ray |
| 152487 | 13 | Gamma Ray |
| 152493 | 1 | Natural Gamma |
| 152504 | 1 | Natural Gamma |
| 152505 | 1 | Natural Gamma |
| 152506 | 1 | Natural Gamma |
| 152507 | 1 | Natural Gamma |
| 152851 | 1 | 64" Normal Resistivity |
| 152852 | 1 | Single-Point Resistance |
| 152857 | 2 | Natural Gamma, Single-Point Resistance |
| 152865 | 7 | Gamma Ray |
| 152871 | 2 | 16" Normal Resistivity, Natural Gamma |
| 152872 | 1 | Natural Gamma |
| 152873 | 2 | 64" Normal Resistivity, Single-Point Resistance |
| 152889 | 2 | 16" Normal Resistivity, Natural Gamma |
| 152893 | 17 | Gamma Ray |
| 152895 | 1 | Natural Gamma |
| 152897 | 1 | Natural Gamma |
| 152898 | 1 | Natural Gamma |
| 152899 | 1 | Natural Gamma |
| 152901 | 1 | Natural Gamma |
| 152902 | 11 | Gamma Ray |
| 152904 | 1 | Natural Gamma |
| 152908 | 1 | Natural Gamma |
| 152953 | 4 | 16" Normal Resistivity, 64" Normal Resistivity, Natural Gamma, Single-Point Resistance |
| 152961 | 8 | Gamma Ray |
| 152967 | 1 | Single-Point Resistance |
| 152968 | 1 | Single-Point Resistance |
| 152978 | 1 | 16" Normal Resistivity |
| 152979 | 1 | 16" Normal Resistivity |
| 152980 | 1 | 64" Normal Resistivity |
| 152984 | 1 | Natural Gamma |
| 152987 | 11 | Gamma Ray |
| 152995 | 1 | Natural Gamma |
| 153000 | 1 | Natural Gamma |
| 153045 | 4 | Gamma Ray |
| 153051 | 1 | Natural Gamma |
| 153072 | 1 | Natural Gamma |
| 153073 | 1 | Natural Gamma |
| 153074 | 1 | Natural Gamma |
| 153075 | 1 | Natural Gamma |
| 153078 | 22 | Gamma Ray |
| 153080 | 9 | Gamma Ray |
| 153082 | 10 | Gamma Ray |
| 153085 | 3 | Gamma Ray |
| 153091 | 2 | Gamma Ray |
| 153092 | 1 | Gamma Ray |
| 153100 | 1 | Natural Gamma |
| 153103 | 6 | Gamma Ray |
| 153147 | 13 | Gamma Ray |
| 153148 | 27 | Gamma Ray |
| 153154 | 28 | Gamma Ray |
| 154161 | 27 | Gamma Ray |
| 154179 | 16 | Gamma Ray |
| 154224 | 8 | Gamma Ray |
| 155232 | 1 | Gamma Ray |
| 155296 | 1 | Single-Point Resistance |
| 155306 | 1 | 16" Normal Resistivity |
| 155315 | 1 | Gamma Ray |
| 155316 | 1 | Single-Point Resistance |
| 155318 | 1 | Natural Gamma |
| 155319 | 1 | Single-Point Resistance |
| 155330 | 19 | Gamma Ray |
| 156392 | 8 | Gamma Ray |
| 156393 | 3 | Gamma Ray |
| 156394 | 1 | Natural Gamma |
| 156399 | 1 | Gamma Ray |
| 156401 | 4 | Gamma Ray |
| 156413 | 1 | Natural Gamma |
| 157453 | 1 | Natural Gamma |
| 157466 | 14 | Gamma Ray |
| 157475 | 1 | Natural Gamma |
| 157489 | 3 | Gamma Ray |
| 157495 | 15 | Gamma Ray |
| 157496 | 27 | Gamma Ray |
| 157499 | 1 | Single-Point Resistance |
| 157500 | 1 | Natural Gamma |
| 157501 | 1 | Single-Point Resistance |
| 157506 | 2 | Natural Gamma, Single-Point Resistance |
| 157509 | 16 | Gamma Ray |
| 157513 | 1 | Single-Point Resistance |
| 157523 | 1 | Natural Gamma |
| 157531 | 1 | 16" Normal Resistivity |
| 157533 | 1 | Single-Point Resistance |
| 157534 | 1 | Single-Point Resistance |
| 157535 | 1 | Single-Point Resistance |
| 157539 | 1 | Single-Point Resistance |
| 157554 | 1 | Natural Gamma |
| 157555 | 9 | Gamma Ray |
| 157556 | 1 | Natural Gamma |
| 157562 | 1 | Natural Gamma |
| 157598 | 1 | Natural Gamma |
| 157689 | 1 | Natural Gamma |
| 157690 | 1 | Natural Gamma |
| 157715 | 9 | Gamma Ray |
| 157801 | 11 | Gamma Ray |
| 157812 | 1 | Natural Gamma |
| 157815 | 12 | Gamma Ray |
| 157840 | 3 | Gamma Ray |
| 157845 | 1 | Gamma Ray |
| 157846 | 2 | Natural Gamma, Single-Point Resistance |
| 157851 | 19 | Gamma Ray |
| 157854 | 1 | Single-Point Resistance |
| 157873 | 19 | Gamma Ray |
| 157881 | 1 | Single-Point Resistance |