Computed 2026-08-20 09:36 from 8 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	10% of schematic structures have data

Independent check: PASS — 100.0000% agreement across 626,697 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 — 99.12% day-level agreement with USGS's own published records for the same gages, across 6 co-listed station(s) and 107,336 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.

8 gage(s) / 126,408 daily values (1927-10-01–2026-07-06); 204 structure(s) with diversion records; 1037 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. 6 gage(s) and 36 structure(s) report in 2026, but structure reporting only reached half its modern level around ~1967. 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)
1920s	1	0
1930s	1	0
1940s	1	0
1950s	3	49
1960s	4	24
1970s	4	100
1980s	4	115
1990s	4	124
2000s	5	120
2010s	5	92
2020s	6	32

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
▸ PINE RIVER BELOW VALLECITO RESERVOIR NEAR BAYFIELD☆ PINBVACO	↓ decreasing	-22.7%	p=0.009	41	~2008

7 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: 10% of 508 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 (1951–2026)

Mass-balance kinks computed for every summer month back to 1951 (746 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.

• LOS PINOS RIVER NEAR IGNACIO, CO: reach shifted from -544 cfs to -180 cfs summer mean (more gaining, p=0.020, 27 yr) [sedimentary plains/foothills: 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=-0.61) -- part of it may be unaccounted water becoming accounted, not hydrologic change]
• SPRING CREEK AT LA BOCA, CO: reach shifted from -587 cfs to -12 cfs summer mean (more gaining, p=0.046, 61 yr) [sedimentary plains/foothills: moderate groundwater connectivity -- gain/loss shifts can be real aquifer response; corroborate with nearby well records]

Groundwater now has its own tab: 120 monitored well(s), water-table trends, stream corridors, and the advisory depletion screen.

Reservoirs now has its own tab: 30 reservoir(s), end-of-year storage back to 1951, click-to-chart histories.

Cross-gage pattern fingerprint

Over the 27-year window with full coverage (2000–2026), the dominant shared pattern across 3 gage(s) explains 90% 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 179 water-level measurements across 120 monitored well(s) (86 alluvial, 0 bedrock, rest unclassified) — plus 4 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 1 well(s) with enough record for a trend test: 0 declining, 0 rising.

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.

LOS PINOS RIVER NEAR IGNACIO, CO: 23 alluvial well(s) nearby. Glover screen: 0.1 cfs of nearby metered alluvial pumping → est. lagged depletion 0.0–0.1 cfs (uncalibrated T/S ranges; flagged for SPDSS calibration, AWAS cross-check, and expert review — DWR's AWAS is the authority).

SPRING CREEK AT LA BOCA, CO: 1 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.

30 reservoir(s) with 2,048 storage measurement(s), 1951–2012. Basin storage as of 2011-10-19 (the record's own end — reservoir records publish ~annually): 58,940 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
▸ VALLECITO RESERVOIR (3103518) ☆	58,751	2010-10-31
▸ VALLECITO RESERVOIR (3103529) ☆	350	1980-08-07
▸ EMERALD LAKE RESERVOIR (3103516) ☆	220	1951-09-01
▸ WOMMER RESERVOIR NO 1 (3103517) ☆	189	2011-10-19
▸ VALLECITO RESERVOIR (3103532) ☆	90	1980-07-10
▸ BELLFLOWER RETENTION RES (3103520) ☆	60	1990-10-31
▸ GOSNEY GRAVEL PIT NO. 1 (3103805) ☆	47	2003-10-31
▸ VALLECITO RESERVOIR (3103531) ☆	37	1980-08-07

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: 1122 across 1037 structure(s); 44 structure(s) carry 1 court-case references.

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 ~1967 — idleness that begins before then may be unreported use, not nonuse (flagged † below).

• EMERALD LAKE RESERVOIR (3103516)☆ (1976-05-12, 0.0 cfs decreed): last active 1951 — 74 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1967) -- early absence of record is weak evidence of nonuse
• LEIGH PIPELINE (3100738)☆ (1973-06-01, 0.1 cfs decreed): last active 1969 — 56 years idle
• COUCH D NO 1 & PUMP PLT (3100602)☆ (1969-03-01, 1.0 cfs decreed): last active 1972 — 53 years idle
• GEORGE B JONES DITCH (3100565)☆ (1911-05-01, 2.5 cfs decreed): last active 1973 — 52 years idle
• COUCH D NO 2 & PUMP PLT (3100603)☆ (1969-03-01, 1.0 cfs decreed): last active 1973 — 52 years idle
• MONTGOMERY DITCH (3100610)☆ (1920-04-23, 4.0 cfs decreed): last active 1973 — 52 years idle
• LOWER WOMMER DITCH NO 1 (3100623)☆ (1900-07-31, 3.0 cfs decreed): last active 1973 — 52 years idle
• LOWER WOMMER DITCH NO 2 (3100624)☆ (1900-07-31, 2.0 cfs decreed): last active 1973 — 52 years idle
• CALMETT NO 1 PUMP AND PL (3100631)☆ (1952-12-31, 0.7 cfs decreed): last active 1973 — 52 years idle
• CURRIE-JACK CREEK PL (3100643)☆ (1965-07-06, 0.0 cfs decreed): last active 1973 — 52 years idle

Compliance screens (102 advisory flags)

Screened 139 of 1037 structures with rights (151 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.

• VALLECITO HYDROELECTRIC (3100844)☆: Observed p99 daily rate 725.0 cfs (max 850.0) exceeds total decreed absolute 720.0 cfs across 40124 recorded day(s).
• KING DITCH (3100519)☆: Observed p99 daily rate 116.0 cfs (max 758.6) exceeds total decreed absolute 106.2 cfs across 47452 recorded day(s).
• SCHRODER IRRIGATION DITCH (3100523)☆: Observed p99 daily rate 64.9 cfs (max 82.0) exceeds total decreed absolute 63.5 cfs across 44216 recorded day(s).
• ROBT MORRISON D HEAIR EX (3100645)☆: Observed p99 daily rate 54.0 cfs (max 56.0) exceeds total decreed absolute 2.5 cfs across 7116 recorded day(s).
• THOMPSON-EPPERSON DITCH (3100511)☆: Observed p99 daily rate 45.0 cfs (max 66.0) exceeds total decreed absolute 35.4 cfs across 41129 recorded day(s).
• BEAR CREEK AND PINE RIVER DITCH (3100514)☆: Observed p99 daily rate 22.6 cfs (max 110.0) exceeds total decreed absolute 14.0 cfs across 47111 recorded day(s).
• CEANABOO DITCH (3100502)☆: Observed p99 daily rate 19.5 cfs (max 26.7) exceeds total decreed absolute 9.8 cfs across 34987 recorded day(s).
• LOS PINOS IRRIGATING DITCH (3100512)☆: Observed p99 daily rate 19.0 cfs (max 35.8) exceeds total decreed absolute 11.5 cfs across 73215 recorded day(s). Structure holds an Augmentation-use decree -- diversions above the direct-flow decree can be lawful under plan operations; interpret with care.
• LA BOCA DITCH (3100507)☆: Observed p99 daily rate 18.0 cfs (max 31.7) exceeds total decreed absolute 14.3 cfs across 22127 recorded day(s).
• KIRKPATRICK DITCH (3100535)☆: Observed p99 daily rate 16.5 cfs (max 22.6) exceeds total decreed absolute 6.5 cfs across 10832 recorded day(s).

Seniority (top structures by decreed rate)

Structure	Senior priority date	Rights	Decreed abs (cfs)	Decreed abs (AF)	Conditional?
VALLECITO HYDROELECTRIC (3100844)☆	1979-06-01	1	720.0	0	—
SPRING CREEK DITCH (3101045)☆	1868-07-25	9	321.2	0	yes
ROBERT MORRISON DITCH (3100547)☆	1890-10-01	6	108.5	0	—
KING DITCH (3100519)☆	1881-05-01	4	106.2	0	—
VALLECITO CREEK INSTREAM FLOW WATER RIGH (3101901)☆	2017-03-23	1	92.0	0	—
DR MORRISON DITCH (3101044)☆	1868-07-25	2	72.6	0	yes
SCHRODER IRRIGATION DITCH (3100523)☆	1881-09-01	4	63.5	0	—
PORTER DITCH (3100583)☆	1936-06-15	2	48.0	0	—
WEMINUCHE PASS DITCH (3104637)☆	1934-07-28	4	40.0	0	—
THOMPSON-EPPERSON DITCH (3100511)☆	1877-12-31	6	35.4	0	—
LOS PINOS RIVER (3101900)☆	1984-07-13	1	32.0	0	—
PINE R WEMINUCHE PASS D (3104638)☆	1934-10-11	3	18.0	0	—
DRY CREEK DITCH (3100660)☆	1900-12-31	1	15.4	0	—
LA BOCA DITCH (3100507)☆	1868-07-25	1	14.3	0	yes
BEAR CREEK AND PINE RIVER DITCH (3100514)☆	1878-05-01	1	14.0	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.

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.