Hydrohistorian
Full diagnostic snapshot pending — this district's weekly-style report (system status, active calls, hydrographs, anomaly flags) is produced by the nightly rotation and appears here after its first run. The tabs above are live now.
Evolution of the network
Gage flow trend & changepoints
What counts as a trend here
Computed 2026-08-20 09:42 from 10 gage(s) with cached period-of-record data. Mann-Kendall (trend) and Pettitt (changepoint) both require at least 8 years spanning at least 10 years of record. A gage below that reports no signal — which is not the same as “no change.”
Of the 10 gages with enough record, 1 is trending down and 0 up, and 1 carries a detected shift. The clearest is PIEDRA RIVER NEAR ARBOLES, CO., -10.5 points of its long-term median per decade over 63 years (p=0.0327). The other 9 show no clear signal either way.
| Gage | Trend | Change / decade points of median | Significance | Years | Changepoint |
|---|---|---|---|---|---|
|
▸
PIEDRA RIVER NEAR ARBOLES, CO. PIEARBCO |
↓ decreasing | -10.5 | p=0.033 | 63 | ~1999 |
9 other gage(s) show no significant trend or changepoint (not shown).
How the measurement network itself changed
This basin was not always measured the way it is today — the API-era record is dense and recent, the early record sparse. 2 gage(s) and 58 structure(s) report in 2026, but structure reporting only reached half its modern level around ~1974. Every historical claim below is checked against this: long-term shifts that co-move with the growth of the network carry an explicit measurement-evolution caution, and abandonment screens whose idleness begins before the modern reporting era are flagged †.
| Decade | Gages with data (median yr) | Structures reporting (median yr) |
|---|---|---|
| 1930s | 3 | 0 |
| 1940s | 4 | 0 |
| 1950s | 2 | 0 |
| 1960s | 2 | 32 |
| 1970s | 2 | 67 |
| 1980s | 1 | 86 |
| 1990s | 2 | 88 |
| 2000s | 2 | 94 |
| 2010s | 2 | 62 |
| 2020s | 2 | 58 |
Mass-balance (network closure) trend
Structure divrec-history backfill coverage as of the last check: 14% of 135 schematic-relevant structures. 0 year(s) clear the 30% coverage gate so far -- the trend activates automatically once qualifying years span a full decade. No action needed; the nightly backfill keeps extending the record.
Reach gain/loss shifts (–)
Mass-balance kinks computed for every summer month back to (0 reach-snapshots) — which reaches gain or lose water, and how that has shifted across decades. Each shift is cross-checked against the observation record above: as more diversions became metered, "unaccounted" water shrinks mechanically, which can masquerade as a hydrologic shift.
No reach shows a statistically significant long-term gain/loss shift.
Groundwater now has its own tab: 44 monitored well(s), water-table trends, stream corridors, and the advisory depletion screen.
Reservoirs now has its own tab: 28 reservoir(s), end-of-year storage back to 1970, click-to-chart histories.
Cross-gage pattern fingerprint
Not enough gages with a long enough common-coverage window yet to fingerprint shared patterns.
Data provenance & quality
Where these numbers come from and how far they can be trusted. Grade C (3/6 points) — the components below are the finding; the letter alone is not. Sources: DWR HydroBase snapshot HydroBase_CO_20260707 (imported 2026-08-19) for history, plus the CDSS REST API for current conditions.
| Check | State | What was measured |
|---|---|---|
| gage freshness | stale | newest gage reading is 45 day(s) old (target 7) |
| diversion record | expected-lag | newest diversion record is 293 day(s) old (DWR publishes ~1 year in arrears) |
| structure coverage | sparse | 14% of schematic structures have data |
Independent check: PASS — 100.0000% agreement across 154,523 stored values re-checked against DWR's authoritative record (HydroBase_CO_20260707), over 20 structures. 0 disagreement(s) beyond a 0.01 cfs tolerance. Checked 2026-08-19; a rotating sample covers the whole basin across successive runs, and the structures this report cites are checked every time.
Federal cross-check: PASS — 99.52% day-level agreement with USGS's own published records for the same gages, across 7 co-listed station(s) and 50,101 overlapping days (within max(2%, 0.5 cfs) daily). Pre-1950 records at some gages carry known between-agency day-stamp and transcription differences — scored at each year's best ±1-day alignment; residual disagreement is real historical divergence, flagged for review.
10 gage(s) / 60,439 daily values (1936-10-01–2026-07-06); 170 structure(s) with diversion records; 366 with decreed rights. Methodology has not yet had independent expert review — treat every figure as an advisory screen, not an administrative or legal conclusion.
243 water-level measurements across 44 monitored well(s) — 33 alluvial, 0 bedrock — plus 2 administered well(s) reporting metered pumping.
What is being counted
Observation wells and pumping wells are different populations and are never conflated: water levels come from monitored observation wells, and metered pumping comes from administered wells reporting through diversion records. Click any well to chart its own record.
Well map
3D aquifer x-ray
Every aquifer unit as its own head surface, animated through time.
How the surfaces are built, and what they are not
Alluvial water table on top, Denver Basin members (Dawson, Denver, Arapahoe, Laramie–Fox Hills) stacked beneath where measured, interpolated from measured water levels. Units are never mixed; a surface exists only inside its own unit's well coverage, with no extrapolation; thin epochs are suppressed and say why. Vertical scale is exaggerated for readability and z is head elevation in feet. These are measured heads, not a calibrated groundwater model.
Water-table trends
Of 1 well(s) with enough record for a trend test: 1 declining, 0 rising.
| Fastest-declining wells | Setting | ft / decade | Span | p |
|---|---|---|---|---|
| ▸ WS-25 | alluvial | -0.53 | 42 yr | 0.0043 |
Wells labeled by administrative world before anything else is said about them: tributary alluvium participates in the priority system; designated-basin and Denver Basin bedrock aquifers are governed differently and are excluded from stream-connection reasoning. Read bedrock declines differently too: deep bedrock aquifers recharge negligibly on human timescales, so a falling bedrock level is storage mining — effectively permanent — not a drought response that a wet year undoes. All screens advisory.
28 reservoir(s) with 5,424 storage measurement(s), 1970–2024. Basin storage as of 2023-10-31 (the record's own end — reservoir records publish ~annually): 14,465 AF across 8 reservoir(s).
Why storage matters to the flow network
Storage change is real water the mass balance must credit — a losing reach beside a filling reservoir isn't losing water, it's banking it.
Reservoir map — how full is each vessel?
What “full” is measured against
Bubble size is proportional to a reservoir's record-high storage. Fill is its last recorded storage as a share of its surveyed capacity (USACE National Inventory of Dams) where a confident NID match exists — the tooltip names the matched dam — and as a share of its own record high otherwise. A wrong capacity would be worse than an honest record high, so only confident joins upgrade.
A dashed teal ring marks reservoirs reporting live DWR telemetry: their fill reflects yesterday's storage, is drawn as a dotted tail on charts, and is treated as provisional until the next verified HydroBase snapshot supersedes it.
Basin storage, end of each water year
End-of-water-year totals; per-year reservoir counts shown because reporting coverage varies -- a total is only comparable to years with similar counts.
Largest reservoirs on record
Click a reservoir to chart its full storage history.
| Reservoir | Last recorded storage (AF) | As of |
|---|---|---|
| ▸ WILLIAMS CREEK RESERVOIR (7803642) | 8,482 | 2023-10-31 |
| ▸ STEVENS RESERVOIR DAM (7803645) | 1,825 | 2022-10-31 |
| ▸ G S HATCHER RESERVOIR (7803626) | 1,635 | 2022-10-31 |
| ▸ LINN AND CLARK RESERVOIR (7803629) | 1,239 | 2022-10-31 |
| ▸ TOWN CENTER LAKE (7803646) | 641 | 2022-10-31 |
| ▸ LAKE FOREST (7803644) | 452 | 2022-10-31 |
| ▸ PARGIN RESERVOIR (7803633) | 337 | 2011-10-31 |
| ▸ PINON LAKE (7803636) | 125 | 2022-10-31 |
Decreed rights on this network run from 1868-03-02 to 2025-06-27. 25 abandonment screens and 85 compliance flags are listed below as leads for review — a screen is not an abandonment and a flag is not a violation.
Rights on file: 435 across 366 structure(s); 30 structure(s) carry 0 court-case references. Advisory reading aids on public DWR data — not administrative or legal conclusions.
Abandonment radar (25 screens)
Absolute rights with 10+ years of no recorded diversions. Screens only — storage, alternate points, and plan operations can explain nonuse lawfully. And diversion REPORTING itself only reached its modern level ~1974 — idleness that begins before then may be unreported use, not nonuse (flagged † below).
- STEVENS SPRING (7800735) (1999-04-10, 0.0 cfs decreed): last active 1968 — 57 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1974) -- early absence of record is weak evidence of nonuse
- BUCY WATER LINE (7800514) (1963-07-07, 0.0 cfs decreed): last active 1970 — 55 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1974) -- early absence of record is weak evidence of nonuse
- HERSCH DITCH (7800561) (1949-08-01, 8.0 cfs decreed): last active 1970 — 55 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1974) -- early absence of record is weak evidence of nonuse
- MARTIN SPG D AND PL NO 1 (7800581) (1928-07-15, 1.0 cfs decreed): last active 1974 — 51 years idle
- PIEDRA STATION PIPE LINE (7800606) (1913-10-01, 0.1 cfs decreed): last active 1974 — 51 years idle
- SANDFORD WATERLINE (7800615) (1968-09-01, 0.0 cfs decreed): last active 1974 — 51 years idle
- YELLOW JACKET PIPE LINE (7800651) (1912-06-10, 0.1 cfs decreed): last active 1974 — 51 years idle
- LINN AND CLARK RESERVOIR (7803629) (1902-06-14, 0.0 cfs decreed): last active 1974 — 51 years idle
- J B MARTINEZ DITCH (7800564) (1883-06-14, 1.2 cfs decreed): last active 1975 — 50 years idle
- TRES PIEDRAS DITCH (7800639) (1943-10-01, 2.0 cfs decreed): last active 1975 — 50 years idle
Compliance screens (85 advisory flags)
Screened 118 of 366 structures with rights (139 have diversion history on file). A flag is a lead for expert review — augmentation plans, exchanges, and free-river conditions can make over-decree diversions lawful and are deliberately not modeled.
- PIEDRA FALLS DITCH (7800604): Observed p99 daily rate 26.1 cfs (max 33.0) exceeds total decreed absolute 26.0 cfs across 25808 recorded day(s).
- GORDON CREEK WETLANDS DIVERSION DITCH (7800756): Observed p99 daily rate 20.0 cfs (max 20.0) exceeds total decreed absolute 4.0 cfs across 1681 recorded day(s).
- FARROW AND PETERSON D (7800545): Observed p99 daily rate 18.4 cfs (max 23.3) exceeds total decreed absolute 16.6 cfs across 26551 recorded day(s).
- J B MARTINEZ DITCH (7800564): Observed p99 daily rate 17.0 cfs (max 20.0) exceeds total decreed absolute 1.2 cfs across 322 recorded day(s).
- CIMARRON DITCH (7800524): Observed p99 daily rate 15.0 cfs (max 15.0) exceeds total decreed absolute 5.0 cfs across 7748 recorded day(s).
- G S HATCHER DITCH (7800550): Observed p99 daily rate 15.0 cfs (max 16.8) exceeds total decreed absolute 7.5 cfs across 1550 recorded day(s).
- M E AND M DITCH (7800580): Observed p99 daily rate 14.4 cfs (max 21.0) exceeds total decreed absolute 12.0 cfs across 15526 recorded day(s).
- CLAYTON-REED DITCH (7800525): Observed p99 daily rate 13.0 cfs (max 13.1) exceeds total decreed absolute 10.0 cfs across 19001 recorded day(s).
- HOSSACK CREEK DITCH (7800562): Observed p99 daily rate 13.0 cfs (max 24.7) exceeds total decreed absolute 10.0 cfs across 10971 recorded day(s).
- J C R DITCH (7800565): Observed p99 daily rate 12.9 cfs (max 19.0) exceeds total decreed absolute 10.0 cfs across 6994 recorded day(s).
Seniority (top structures by decreed rate)
| Structure | Senior priority date | Rights | Decreed abs (cfs) | Decreed abs (AF) | Conditional? |
|---|---|---|---|---|---|
| PIEDRA RIVER MIN FLOW (7801903) | 1978-03-16 | 1 | 70.0 | 0 | — |
| PIEDRA RIVER MIN FLOW (7801910) | 1979-03-14 | 1 | 70.0 | 0 | — |
| PIEDRA RIVER MIN FLOW (7801902) | 1978-03-16 | 1 | 53.0 | 0 | — |
| PIEDRA RIVER MIN FLOW (7801901) | 1978-03-16 | 1 | 44.0 | 0 | — |
| LINN AND CLARK DITCH (7800578) | 1902-06-14 | 1 | 36.5 | 0 | — |
| PIEDRA RIVER MIN FLOW (7801900) | 1978-03-16 | 1 | 30.0 | 0 | — |
| PIEDRA FALLS DITCH (7800604) | 1934-07-18 | 2 | 26.0 | 0 | yes |
| LITTLE PAGOSA CREEK DIVR (7800659) | 1939-12-31 | 1 | 26.0 | 0 | — |
| BARNES-MEUSER AND SHAW D (7800507) | 1903-12-31 | 3 | 22.5 | 0 | — |
| BUCKSKIN-NAILOR DITCH (7800513) | 1900-03-20 | 7 | 21.9 | 0 | — |
| PERKINS DITCH - STOLLSTEIMER CREEK (7800600) | 1963-07-28 | 1 | 20.0 | 0 | — |
| ABRAHAM DAVIS DITCH (7800501) | 1900-04-01 | 4 | 18.0 | 0 | — |
| WEMINUCHE CR MIN FLOW (7801909) | 1978-03-16 | 1 | 18.0 | 0 | — |
| FARROW AND PETERSON D (7800545) | 1879-04-10 | 6 | 16.6 | 0 | — |
| F S MOCKLER IRR DITCH (7800544) | 1901-10-01 | 1 | 15.0 | 0 | — |
No inventory or legal-document changes detected since the daily watch began.
If a call were placed at a given seniority, which structures in this basin would be out of priority, and how much of their decreed rate would be curtailed? Computed from this basin's cached decrees.
What this does and doesn't model. Seniority arithmetic only: every right junior to the call is treated as curtailed. It does not model reach applicability — structures downstream of the calling point are not administered by it — and it applies no futile-call judgment. Read it as “who is junior to this date, and by how much,” not as a prediction of what the Division Engineer would actually order.
Pick a calling right
Real decrees from this basin, ordered by administration number — that is, by actual seniority. The years will look out of order, and that is correct: an administration number encodes the adjudication date as well as the appropriation date, so a right appropriated in 1970 can be administered ahead of one from 1950. A senior call curtails almost everything; a junior one curtails almost nothing.
Or enter an administration number directly
DWR administration numbers encode appropriation and adjudication dates; lower is more senior.