Computed 2026-08-20 08:50 from 35 gage(s) with cached period-of-record data. Statistical tests (Mann-Kendall trend, Pettitt changepoint) require at least 8 years spanning at least 10 years of record -- gages below that report no signal, not "no change."

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	7% of schematic structures have data

Independent check: PASS — 100.0000% agreement across 110,484 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 — 99.98% day-level agreement with USGS's own published records for the same gages, across 10 co-listed station(s) and 212,763 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.

35 gage(s) / 320,317 daily values (1903-04-01–2026-07-06); 189 structure(s) with diversion records; 1764 with decreed rights. Methodology has not yet had independent expert review — treat every figure as an advisory screen, not an administrative or legal conclusion.

Read this first: the measurement network itself evolved

This basin was not always measured the way it is today — the API-era record is dense and recent, the early record sparse. 29 gage(s) and 123 structure(s) report in 2026, but structure reporting only reached half its modern level around ~1950. 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	1	0
1910s	2	0
1920s	5	0
1930s	5	0
1940s	6	0
1950s	6	92
1960s	6	92
1970s	6	95
1980s	9	97
1990s	8	125
2000s	12	128
2010s	13	120
2020s	23	102

Gage flow trend & changepoints

Every located gage with a period of record — dot size scales with the strength of its flow trend (|Sen slope| in %/decade, the same statistic as the table below), color with direction. An amber ring marks a detected Pettitt changepoint. Click a gage to chart its trend and shift.

Gage	Trend	Change / decade	Significance	Years	Changepoint
▸ ROMERO DITCH NEAR CONEJOS☆ ROMDITCO	↓ decreasing	-409.7%	p=0.000	25	~2013
▸ NORTH BRANCH CONEJOS RIVER NEAR CONEJOS☆ NORCONCO	↓ decreasing	-226.3%	p=0.000	26	~2016
▸ MANASSA DITCH NEAR CONEJOS☆ MANDITCO	↓ decreasing	-154.5%	p=0.000	28	~2011
▸ SAN ANTONIO RIVER AT ORTIZ☆ SANORTCO	↓ decreasing	-11.0%	p=0.000	102	~1943
▸ LOS PINOS RIVER NEAR ORTIZ☆ LOSORTCO	↓ decreasing	-2.3%	p=0.038	108	—

30 other gage(s) show no significant trend or changepoint (not shown).

Mass-balance (network closure) trend

Structure divrec-history backfill coverage as of the last check: 7% of 1300 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 (1950–2026)

Mass-balance kinks computed for every summer month back to 1950 (1493 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.

• SAN ANTONIO RIVER NEAR MANASSA: reach shifted from -438 cfs to +79 cfs summer mean (more gaining, p=0.000, 76 yr) [sedimentary uplands: moderate groundwater connectivity -- gain/loss shifts can be real aquifer response; corroborate with nearby well records] [measurement-evolution caution: this shift co-moves with the growth of the gage/metering network (rho=0.45) -- part of it may be unaccounted water becoming accounted, not hydrologic change]
• SOUTH CHANNEL CONEJOS RIVER NEAR LA SAUSES: reach shifted from -148 cfs to +6 cfs summer mean (more gaining, p=0.000, 39 yr) [sedimentary uplands: moderate groundwater connectivity -- gain/loss shifts can be real aquifer response; corroborate with nearby well records]
• CONEJOS RIVER NEAR CONEJOS: reach shifted from -25 cfs to -38 cfs summer mean (more losing, p=0.019, 28 yr) [sedimentary uplands: moderate groundwater connectivity -- gain/loss shifts can be real aquifer response; corroborate with nearby well records]

Groundwater now has its own tab: 140 monitored well(s), water-table trends, stream corridors, and the advisory depletion screen.

Reservoirs now has its own tab: 3 reservoir(s), end-of-year storage back to 1950, click-to-chart histories.

Cross-gage pattern fingerprint

Over the 102-year window with full coverage (1925–2026), the dominant shared pattern across 3 gage(s) explains 70% of year-to-year variance (almost certainly a basin-wide climate/snowpack driver).

All gages in this window move with the shared pattern -- no localized outlier.

The basin's aquifer story, from 17,980 water-level measurements across 140 monitored well(s) (30 alluvial, 45 bedrock, rest unclassified) — plus 0 administered well(s) reporting metered pumping through diversion records. Observation wells and pumping wells are different populations and are never conflated. Click a well to chart its record.

Well map

Every monitored well with a location — hover for identity, click to chart its water-level record below. ● alluvial   ● bedrock / confined (Denver Basin, High Plains, etc. — one-way, no human-timescale recharge)   ● unclassified — marker size scales with the strength of the well's water-level trend (|Sen slope| in ft/decade — the same Mann-Kendall/Sen statistic as the trends table below); the smallest, faintest dots have too little record to test.

3D aquifer x-ray

Every aquifer unit as its own 3D head surface — alluvial water table on top, Denver Basin members (Dawson, Denver, Arapahoe, Laramie–Fox Hills) stacked beneath where measured — interpolated from measured water levels and animated through time. Units are never mixed; surfaces exist only inside each unit's well coverage (no extrapolation); thin epochs are suppressed with their reason shown. Vertical scale exaggerated for readability; z is head elevation in feet. Advisory — measured heads, not a calibrated model.

Load 3D x-ray

Water-table trends

Of 17 well(s) with enough record for a trend test: 5 declining, 1 rising.

Fastest-declining wells	Setting	ft / decade	Span	p
▸ NA03300934CB☆	unknown	-5.82	18 yr	0.0
▸ NA03501012BBC CON 2☆	unknown	-2.27	55 yr	0.0
▸ NA03400931DDD RG86☆	alluvial	-1.74	50 yr	0.0272
▸ NA03300934DAA RG96A☆	alluvial	-1.18	49 yr	0.0033
▸ NA03300911CBB☆	alluvial	-0.55	49 yr	0.0

Stream corridors — the surface connection

For each reach whose gain/loss has shifted (Trends tab), the wells within 2 miles of its anchoring gage, their pooled water-table history over the same era, and an advisory Glover screen of lagged stream depletion from nearby metered pumping. v1 proximity = distance to the reach's anchoring gage; segment-based reach join is a flagged upgrade.

SAN ANTONIO RIVER NEAR MANASSA: 1 alluvial well(s) nearby

SOUTH CHANNEL CONEJOS RIVER NEAR LA SAUSES: 2 alluvial well(s) nearby

CONEJOS RIVER NEAR CONEJOS: 0 alluvial well(s) nearby

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.

3 reservoir(s) with 10,450 storage measurement(s), 1950–2026. Basin storage as of 2025-10-31 (the record's own end — reservoir records publish ~annually): 25,718 AF across 2 reservoir(s). 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?

Each reservoir drawn as a vessel: bubble size ∝ its record-high storage, fill level = 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 of its own record high otherwise (a wrong capacity would be worse than an honest record high, so only confident joins upgrade). Hover for numbers, click to chart its history below the map. A dashed teal ring marks reservoirs reporting live DWR telemetry — their fill reflects yesterday's storage, drawn as a dotted tail on charts and treated as provisional until the next verified HydroBase snapshot supersedes it. ● <25% ● 25–60% ● 60–90% ● >90%

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
▸ PLATORO RESERVOIR (2203574) ☆	24,848	2025-10-30
▸ COVE LAKE RES (2203573) ☆	884	1964-10-01
▸ TRUJILLO MEADOWS RES (2203575) ☆	870	2025-10-31

Decrees, seniority, and administrative calls connected to this basin's flow network. Advisory reading aids on public DWR data — not administrative or legal conclusions. Rights on file: 1980 across 1764 structure(s); 94 structure(s) carry 0 court-case references.

Abandonment radar (6 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 ~1950 — idleness that begins before then may be unreported use, not nonuse (flagged † below).

• MANASSA D NO 2 (2200592)☆ (1883-04-21, 23.2 cfs decreed): last active 1973 — 40 years idle
• JOHN W FLOYD OVRFLW NO 2 (2200572)☆ (1883-04-21, 2.2 cfs decreed): last active 1974 — 39 years idle
• JOHN W FLOYD OVRFLW NO 3 (2200573)☆ (1883-04-21, 5.0 cfs decreed): last active 1974 — 39 years idle
• COLD SPRINGS D (2200529)☆ (1911-08-05, 1.1 cfs decreed): last active 1975 — 38 years idle
• BALL BROS OVERFLOW NO 2 (2200510)☆ (1883-04-21, 20.0 cfs decreed): last active 1988 — 25 years idle
• BOSQUE IRRIGATING D (2200514)☆ (1913-04-17, 3.0 cfs decreed): last active 2003 — 10 years idle

Compliance screens (100 advisory flags)

Screened 132 of 1764 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.

• TAOS VALLEY CANAL NO 3 (2200639)☆: Observed p99 daily rate 265.0 cfs (max 300.0) exceeds total decreed absolute 15.0 cfs across 7204 recorded day(s).
• LOVATO D (2200588)☆: Observed p99 daily rate 130.0 cfs (max 145.0) exceeds total decreed absolute 7.5 cfs across 4590 recorded day(s).
• NORTH EASTERN D (2200609)☆: Observed p99 daily rate 122.0 cfs (max 130.0) exceeds total decreed absolute 92.8 cfs across 9339 recorded day(s).
• SELEDONIA VALDEZ IRR MIL (2200630)☆: Observed p99 daily rate 85.8 cfs (max 310.0) exceeds total decreed absolute 31.8 cfs across 18076 recorded day(s).
• LOVATO IRR D (2200589)☆: Observed p99 daily rate 80.0 cfs (max 140.0) exceeds total decreed absolute 53.1 cfs across 11586 recorded day(s). Structure holds an Augmentation-use decree -- diversions above the direct-flow decree can be lawful under plan operations; interpret with care.
• HEADS MILL & IRG D (2200554)☆: Observed p99 daily rate 68.0 cfs (max 95.0) exceeds total decreed absolute 61.1 cfs across 29350 recorded day(s).
• ALAMO D (2200501)☆: Observed p99 daily rate 55.0 cfs (max 56.5) exceeds total decreed absolute 53.5 cfs across 8358 recorded day(s).
• TROGILLO D (2200644)☆: Observed p99 daily rate 53.5 cfs (max 53.5) exceeds total decreed absolute 53.5 cfs across 9284 recorded day(s).
• GUADALUPE MAIN (2200553)☆: Observed p99 daily rate 52.0 cfs (max 76.0) exceeds total decreed absolute 13.5 cfs across 34637 recorded day(s).
• SAN JUAN SAN RAFAEL D (2200624)☆: Observed p99 daily rate 52.0 cfs (max 75.0) exceeds total decreed absolute 51.8 cfs across 17362 recorded day(s).

Seniority (top structures by decreed rate)

Structure	Senior priority date	Rights	Decreed abs (cfs)	Decreed abs (AF)	Conditional?
USFS QP23W (2200946)☆	1907-03-02	1	2828.6	0	—
USFS QP23U (2200945)☆	1905-06-03	1	1736.6	0	—
USFS QP22H (2200924)☆	1907-03-02	1	612.2	0	—
USFS QP23H (2200932)☆	1905-06-03	1	537.2	0	—
USFS QP23M (2200940)☆	1905-06-03	1	520.4	0	—
USFS QP23N (2200941)☆	1905-06-03	1	365.2	0	—
MOGOTE DITCH (2200591)☆	1887-06-02	1	342.4	0	—
USFS QP23F (2200930)☆	1907-03-02	1	339.8	0	—
USFS QP22A (2200917)☆	1905-06-03	1	181.8	0	—
MANASSA D NO 3 (2200593)☆	1855-03-01	10	169.6	2	—
RICHFIELD CANAL (2200616)☆	1881-10-12	2	168.7	0	—
ROMERO D (2200619)☆	1855-03-01	9	165.0	0	—
NORTON DRAIN MAIN BRANCH (2200912)☆	1968-04-29	2	150.0	0	—
SANFORD D (2200627)☆	1885-10-20	2	146.3	0	—
USFS QP23H4 (2200936)☆	1905-06-03	1	140.8	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.

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

Administration number
Simulate

DWR administration numbers encode appropriation and adjudication dates; lower is more senior.