Computed 2026-08-20 09:28 from 12 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 D (2/6 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 9090 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	34% of schematic structures have data

Independent check: PASS — 100.0000% agreement across 193,010 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 — 100.00% day-level agreement with USGS's own published records for the same gages, across 12 co-listed station(s) and 52,805 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) / 52,816 daily values (1955-10-01–2001-09-30); 293 structure(s) with diversion records; 1003 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. 0 gage(s) and 136 structure(s) report in 2025, but structure reporting only reached half its modern level around ~1985. 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	1
1910s	0	1
1930s	0	60
1940s	0	58
1950s	0	50
1960s	2	50
1970s	4	68
1980s	4	82
1990s	3	84
2000s	0	90
2010s	0	124
2020s	0	131

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
▸ FOIDEL CREEK NEAR OAK CREEK, CO☆ FOIDATCO	↑ increasing	+74.4%	p=0.018	25	~1983
▸ YAMPA RIVER BELOW DIVERSION, NEAR HAYDEN, CO.☆ YAMDIVCO	no clear trend	+20.2%	p=0.174	21	~1981

10 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: 34% of 121 schematic-relevant structures. 1 year(s) clear the 30% coverage gate so far (2017–2017) -- 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 (1980–1997)

Mass-balance kinks computed for every summer month back to 1980 (8 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: 129 monitored well(s), water-table trends, stream corridors, and the advisory depletion screen.

Reservoirs now has its own tab: 165 reservoir(s), end-of-year storage back to 1939, click-to-chart histories.

Cross-gage pattern fingerprint

Over the 17-year window with full coverage (1985–2001), the dominant shared pattern across 3 gage(s) explains 93% 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 1,311 water-level measurements across 129 monitored well(s) (99 alluvial, 0 bedrock, rest unclassified) — plus 13 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 0 well(s) with enough record for a trend test: 0 declining, 0 rising.

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.

165 reservoir(s) with 7,025 storage measurement(s), 1939–2026. Basin storage as of 2025-10-31 (the record's own end — reservoir records publish ~annually): 1,156 AF across 30 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
▸ J C TEMPLE RES 1 (5703572) ☆	367	2025-10-31
▸ HAYDEN RAW WATER RES (5703786) ☆	311	2015-10-31
▸ SHERIFF RES (5703583) ☆	280	2025-10-31
▸ WADGE PIT RES (5703793) ☆	172	2019-10-31
▸ WOLF MOUNTAIN RES (5703516) ☆	138	2025-10-31
▸ INTERMEDIATE QUALITY P (5704002) ☆	100	2015-10-31
▸ SEDIMENTATION POND A (5703501) ☆	84	2025-10-31
▸ POND D (5703536) ☆	75	2014-10-31

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: 1336 across 1003 structure(s); 26 structure(s) carry 0 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 ~1985 — idleness that begins before then may be unreported use, not nonuse (flagged † below).

• EAST SIGNS SPRING (5700684)☆ (1972-03-20, 0.0 cfs decreed): last active 1957 — 68 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1985) -- early absence of record is weak evidence of nonuse
• TOW CREEK DITCH 2 (5700602)☆ (1890-06-01, 2.0 cfs decreed): last active 1958 — 67 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1985) -- early absence of record is weak evidence of nonuse
• ECKMAN PARK DITCH 1 (5700529)☆ (1905-06-10, 13.3 cfs decreed): last active 1974 — 51 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1985) -- early absence of record is weak evidence of nonuse
• WATTS SPRING C (5700634)☆ (1925-06-01, 1.0 cfs decreed): last active 1974 — 51 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1985) -- early absence of record is weak evidence of nonuse
• FOX SPRING 1 (5700644)☆ (1905-06-14, 0.2 cfs decreed): last active 1974 — 51 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1985) -- early absence of record is weak evidence of nonuse
• TABB SPRING & PL (5700660)☆ (1952-07-06, 0.1 cfs decreed): last active 1974 — 51 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1985) -- early absence of record is weak evidence of nonuse
• ESKRIDGE SPRING 1 (5700665)☆ (1970-10-08, 0.0 cfs decreed): last active 1974 — 51 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1985) -- early absence of record is weak evidence of nonuse
• BIG SPRING (5700666)☆ (1915-06-01, 0.1 cfs decreed): last active 1974 — 51 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1985) -- early absence of record is weak evidence of nonuse
• MATHEWS SPRING (5700669)☆ (1933-05-12, 0.1 cfs decreed): last active 1974 — 51 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1985) -- early absence of record is weak evidence of nonuse
• MCKUNE SPRING 1 (5700670)☆ (1951-07-19, 0.0 cfs decreed): last active 1974 — 51 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1985) -- early absence of record is weak evidence of nonuse

Compliance screens (100 advisory flags)

Screened 160 of 1003 structures with rights (217 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.

• GIBRALTAR DITCH (5700539)☆: Observed p99 daily rate 90.0 cfs (max 340.6) exceeds total decreed absolute 70.0 cfs across 28831 recorded day(s). Structure holds an Augmentation-use decree -- diversions above the direct-flow decree can be lawful under plan operations; interpret with care.
• SHELTON DITCH (5700592)☆: Observed p99 daily rate 56.0 cfs (max 80.0) exceeds total decreed absolute 53.5 cfs across 32642 recorded day(s).
• WALKER IRRIG DITCH (5700611)☆: Observed p99 daily rate 48.0 cfs (max 55.7) exceeds total decreed absolute 42.7 cfs across 35764 recorded day(s).
• CARY DITCH COMPANY IRRIGATING DITCH (5700510)☆: Observed p99 daily rate 41.2 cfs (max 48.2) exceeds total decreed absolute 29.0 cfs across 26302 recorded day(s).
• MARSHALL ROBERTS DITCH (5700563)☆: Observed p99 daily rate 34.1 cfs (max 80.0) exceeds total decreed absolute 19.2 cfs across 25557 recorded day(s).
• BROCK DITCH (5700508)☆: Observed p99 daily rate 27.0 cfs (max 37.6) exceeds total decreed absolute 21.5 cfs across 25152 recorded day(s).
• WILLIAMS IRRIG DITCH (5700622)☆: Observed p99 daily rate 23.8 cfs (max 34.2) exceeds total decreed absolute 19.4 cfs across 28364 recorded day(s).
• TROUT CREEK DITCH 3 (5700608)☆: Observed p99 daily rate 19.2 cfs (max 25.0) exceeds total decreed absolute 12.7 cfs across 17767 recorded day(s). Structure holds an Augmentation-use decree -- diversions above the direct-flow decree can be lawful under plan operations; interpret with care.
• KOLL DITCH (5700635)☆: Observed p99 daily rate 17.3 cfs (max 19.9) exceeds total decreed absolute 13.2 cfs across 18555 recorded day(s).
• R E CLARK DITCH (5700579)☆: Observed p99 daily rate 16.0 cfs (max 50.0) exceeds total decreed absolute 12.4 cfs across 12944 recorded day(s).

Seniority (top structures by decreed rate)

Structure	Senior priority date	Rights	Decreed abs (cfs)	Decreed abs (AF)	Conditional?
GIBRALTAR DITCH (5700539)☆	1888-03-18	3	70.0	0	—
SHELTON DITCH (5700592)☆	1883-04-15	3	53.5	0	—
WALKER IRRIG DITCH (5700611)☆	1882-05-01	7	42.7	0	—
CARY DITCH COMPANY IRRIGATING DITCH (5700510)☆	1887-11-07	3	29.0	0	—
COLORADO UTILITIES DITCH AND PIPELINE (5700856)☆	1926-08-12	4	27.0	0	—
BROCK DITCH (5700508)☆	1883-03-30	6	21.5	0	—
WILLIAMS IRRIG DITCH (5700622)☆	1881-10-20	7	19.4	0	—
RICH DITCH (5704629)☆	1896-10-08	6	19.3	0	—
LAST CHANCE DITCH (5700555)☆	1902-06-01	6	19.3	0	—
MARSHALL ROBERTS DITCH (5700563)☆	1881-10-20	5	19.2	0	—
HOMESTEAD DITCH (5700545)☆	1901-05-01	4	15.9	0	—
CONNELL DITCH (5700513)☆	1889-08-15	2	15.7	0	—
HIGHLAND DITCH (5700544)☆	1889-09-13	2	15.7	0	—
DENNIS & BLEWITT DITCH (5700519)☆	1888-11-14	4	14.7	0	yes
ECKMAN PARK DITCH 1 (5700529)☆	1905-06-10	1	13.3	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.