Hydrohistorian
Evolution of the network
Gage flow trend & changepoints
What counts as a trend here
Computed 2026-08-20 08:37 from 12 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 12 gages with enough record, 1 is trending down and 0 up. The clearest is ST. CHARLES RIVER AT BURNT MILL, CO., -244.7 points of its long-term median per decade over 12 years (p=0.0164). The other 11 show no clear signal either way.
| Gage | Trend | Change / decade points of median | Significance | Years | Changepoint |
|---|---|---|---|---|---|
|
▸
ST. CHARLES RIVER AT BURNT MILL, CO. STCBURCO |
↓ decreasing | -244.7 | p=0.016 | 12 | — |
11 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. 4 gage(s) and 65 structure(s) report in 2026, but structure reporting only reached half its modern level around ~1912. 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) |
|---|---|---|
| 1900s | 0 | 12 |
| 1910s | 0 | 53 |
| 1920s | 1 | 58 |
| 1930s | 1 | 72 |
| 1940s | 1 | 65 |
| 1950s | 0 | 55 |
| 1960s | 0 | 49 |
| 1970s | 2 | 78 |
| 1980s | 1 | 73 |
| 1990s | 1 | 58 |
| 2000s | 2 | 71 |
| 2010s | 4 | 69 |
| 2020s | 4 | 65 |
Mass-balance (network closure) trend
Structure divrec-history backfill coverage as of the last check: 3% of 824 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 (1974–2025)
Mass-balance kinks computed for every summer month back to 1974 (135 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: 80 monitored well(s), water-table trends, stream corridors, and the advisory depletion screen.
Reservoirs now has its own tab: 9 reservoir(s), end-of-year storage back to 1950, click-to-chart histories.
Cross-gage pattern fingerprint
Over the 12-year window with full coverage (2015–2026), the dominant shared pattern across 3 gage(s) explains 46% of year-to-year variance (almost certainly a basin-wide climate/snowpack driver).
COMRETCO doesn't move with that shared pattern -- a real, localized signal (a new diversion, land-use change, or a gage-specific data problem) worth a closer look, not necessarily noise.
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 | 3% of schematic structures have data |
Independent check: PASS — 100.0000% agreement across 212,966 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 — 99.95% day-level agreement with USGS's own published records for the same gages, across 8 co-listed station(s) and 36,555 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.
12 gage(s) / 57,881 daily values (1923-03-01–2026-07-06); 182 structure(s) with diversion records; 704 with decreed rights. Methodology has not yet had independent expert review — treat every figure as an advisory screen, not an administrative or legal conclusion.
343 water-level measurements across 80 monitored well(s) — 18 alluvial, 0 bedrock — plus 5 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 |
|---|---|---|---|---|
| ▸ SC02106523ADC | alluvial | -2.65 | 44 yr | 0.0003 |
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.
9 reservoir(s) with 2,308 storage measurement(s), 1950–2014. Basin storage as of 2013-10-31 (the record's own end — reservoir records publish ~annually): 893 AF across 1 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 |
|---|---|---|
| ▸ ST CHARLES RES NO 3 (1503829) | 6,033 | 2000-10-30 |
| ▸ ST CHARLES RES NO 2 (1503828) | 2,047 | 2000-10-30 |
| ▸ LAKE ISABEL (1503830) | 1,069 | 1952-11-01 |
| ▸ HAYDEN RESERVOIR (1503695) | 893 | 2013-10-31 |
| ▸ BONNIEMEADE RESERVOIR (1503694) | 200 | 1997-05-20 |
| ▸ CLARK RESERVOIR NO 1 (7903728) | 100 | 1994-10-15 |
| ▸ HICKLAND RESERVOIR NO 2 (1503696) | 5 | 1997-07-01 |
| ▸ NAUMANN POND (1503512) | 0 | 2009-10-31 |
Decreed rights on this network run from 1859-05-01 to 2022-12-13. 25 abandonment screens and 58 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: 957 across 704 structure(s); 29 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 ~1912 — idleness that begins before then may be unreported use, not nonuse (flagged † below).
- GREENHORN HIGHLINE DITCH (1500539) (1859-05-01, 10.9 cfs decreed): last active 1934 — 91 years idle
- FISHER CANON DITCH NO 2 (1500560) (1893-06-27, 2.0 cfs decreed): last active 1939 — 86 years idle
- MEXICAN DITCH (1500585) (1867-02-20, 2.0 cfs decreed): last active 1957 — 68 years idle
- MCDANIEL DITCH NO 3 (1500569) (1879-11-30, 0.1 cfs decreed): last active 1973 — 52 years idle
- MOORE'S SPRING PIPELINE (1500617) (1906-06-30, 0.5 cfs decreed): last active 1973 — 52 years idle
- DAVIS DITCH (1500533) (1873-06-01, 0.9 cfs decreed): last active 1974 — 51 years idle
- COLORADO CITY WELL NO 3 (1505593) (1965-08-25, 0.6 cfs decreed): last active 1974 — 51 years idle
- CRAWFORD & SMYTHE DITCH (1500531) (1870-03-01, 3.7 cfs decreed): last active 1975 — 50 years idle
- PIERSON SPRING DITCH (1500619) (1868-05-01, 1.8 cfs decreed): last active 1975 — 50 years idle
- IRON SPRINGS PIPELINE (1500642) (1901-12-31, 0.3 cfs decreed): last active 1982 — 43 years idle
Compliance screens (58 advisory flags)
Screened 105 of 704 structures with rights (117 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.
- DOTSON DITCH NO 1 (1500507): Observed p99 daily rate 26.2 cfs (max 266.0) exceeds total decreed absolute 26.0 cfs across 47152 recorded day(s).
- A J LAMB DITCH (1500567): Observed p99 daily rate 11.2 cfs (max 15.5) exceeds total decreed absolute 7.3 cfs across 7705 recorded day(s).
- GREENHORN HIGHLINE DITCH (1500539): Observed p99 daily rate 11.0 cfs (max 11.0) exceeds total decreed absolute 10.9 cfs across 2376 recorded day(s).
- HICKLIN DITCH "A" (1500538): Observed p99 daily rate 10.0 cfs (max 29.4) exceeds total decreed absolute 0.7 cfs across 38112 recorded day(s).
- HICKLIN DITCH "B" (1500540): Observed p99 daily rate 10.0 cfs (max 20.0) exceeds total decreed absolute 1.7 cfs across 2732 recorded day(s).
- CRAWFORD & SMYTHE DITCH (1500531): Observed p99 daily rate 6.0 cfs (max 8.0) exceeds total decreed absolute 3.7 cfs across 9180 recorded day(s).
- STANLEY DITCH NO 1 (1500554): Observed p99 daily rate 5.8 cfs (max 38.0) exceeds total decreed absolute 1.5 cfs across 5902 recorded day(s).
- WAGNER DITCH (1500524): Observed p99 daily rate 4.2 cfs (max 8.0) exceeds total decreed absolute 1.5 cfs across 10596 recorded day(s).
- MARINCICH PUMP (1500525): Observed p99 daily rate 4.2 cfs (max 4.6) exceeds total decreed absolute 0.8 cfs across 1454 recorded day(s).
- CHASE DITCH (1500506): Observed p99 daily rate 4.0 cfs (max 11.5) exceeds total decreed absolute 2.0 cfs across 7370 recorded day(s).
Seniority (top structures by decreed rate)
| Structure | Senior priority date | Rights | Decreed abs (cfs) | Decreed abs (AF) | Conditional? |
|---|---|---|---|---|---|
| ST CHARLES FLOOD DITCH (1500522) | 1861-09-01 | 16 | 1135.4 | 0 | — |
| HAYDEN SUPPLY DITCH (1500537) | 1859-05-01 | 11 | 70.0 | 0 | — |
| DOTSON DITCH NO 1 (1500507) | 1865-05-31 | 4 | 26.0 | 0 | — |
| BRYSON DITCH (1500504) | 1883-10-31 | 3 | 11.6 | 0 | — |
| GREENHORN HIGHLINE DITCH (1500539) | 1859-05-01 | 16 | 10.9 | 0 | — |
| A J LAMB DITCH (1500567) | 1869-12-31 | 7 | 7.3 | 0 | — |
| POLLARD DITCH (1500518) | 1866-12-15 | 2 | 6.0 | 0 | — |
| HIGHLINE DITCH (1500541) | 1869-03-01 | 4 | 5.4 | 0 | — |
| PIONEER MIDDLE CREEK (1500517) | 1866-06-30 | 4 | 5.1 | 0 | — |
| MIDDLE CREEK MIN FLOW - LOWER (1503008) | 2010-01-26 | 1 | 5.1 | 0 | — |
| RYE FISH HATCHERY P/L #2 (1500550) | 1939-09-15 | 1 | 5.0 | 0 | — |
| SHURTZ DITCH (1500553) | 1868-04-01 | 6 | 4.9 | 0 | — |
| GREENHORN CREEK MIN FLOW (1503003) | 1998-05-11 | 1 | 4.8 | 0 | — |
| BRYSON PUMP NO 1 (1500757) | 1870-01-02 | 2 | 4.5 | 0 | — |
| GREENHORN VALLEY DITCH (1500536) | 1859-05-01 | 14 | 4.2 | 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.
Each row shows a streamgage where the upstream walk (headwater seed ± diversions ± returns ± tributaries) disagrees with the gage reading. Possible reasons include ungaged diversions/returns, channel losses, or structures with stale telemetry.
| Stream | Gage | R-mile | Predicted (cfs) | Observed (cfs) | Δ (cfs) | Reach (mi) | Hypothesis |
|---|---|---|---|---|---|---|---|
| MAINSTEM | SAINT CHARLES RIVER AT VINELAND (STCHARCO) | 61.4 | 5.3 | 56.6 | +51.2 | 10.1 | Unaccounted +51.2 cfs gain over 10.1 mi. No structure clearly responsible — possible ungaged return flow, baseflow from groundwater, or unmodeled tributary inflow. |
| MAINSTEM | COMANCHE RETURN FLOW (COMRETCO) | 51.3 | 0.3 | 5.3 | +5.0 | 37.4 | Unaccounted +5.0 cfs gain over 37.4 mi. No structure clearly responsible — possible ungaged return flow, baseflow from groundwater, or unmodeled tributary inflow. |
| Gage ⇅ | Station ⇅ | Avg cfs Aug 10–Aug 16 ⇅ |
% Hist Median ⇅ | Rank ⇅ | Δ1wk ⇅ | Δ4wk ⇅ | Yrs ⇅ | Status ⇅ |
|---|---|---|---|---|---|---|---|---|
| GRECRKCO | GREENHORN CREEK ABOVE RYE CO | 0.3 | 10% | 0 | +0 | +0 | 19.1 | SHORT_RECORD |
| SHRDITCO | SHURTZ DITCH ABOVE RYE CO | 0.0 | 0% | 0 | +0 | +0 | 19.2 | SHORT_RECORD |
| COMRETCO | COMANCHE RETURN FLOW | 2.3 | 77% | 0 | -0 | -0 | 18.1 | SHORT_RECORD |
| STCHARCO | SAINT CHARLES RIVER AT VINELAND | 56.6 | 240% | 77 | +48 | +54 | 47.8 | OK |
Call details in gantt above
3 alert(s) · 0 warning(s) · 3 info. Each gage contributes at most one flag per category (its single most-severe match), so this list shouldn't multiply-count the same underlying condition.