Upper Gunnison River

Evolution of the network

Source Our computation, no independent reference · computed here from the screened DWR record Source Our computation, no independent reference · no independent reference; see /methods

This year, in context

In the weeks around 2026-07-06 (the newest reading on file), flows at the 6 ranked gages are running at a median 23% of their own long-term norm for this window — 6 below a typical year, 0 at or above. Driest relative to its record: CIMARRON RIVER BLW SQUAW CREEK AT CIMARRON, CO, ranking 2nd lowest of 26 years.

Gage flow trend & changepoints

Of the 14 gages with enough record, 0 are trending down and 0 up. The other 13 show no clear signal either way. 1 transbasin gage meters imported or exported water — marked ⇆ below and kept out of these counts, because that flow is an operator's decision, not the basin's hydrology (all transbasin diversions).

13 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. 6 gage(s) and 164 structure(s) report in 2026, but structure reporting only reached half its modern level around ~1986. 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 †.

Mass-balance (network closure) trend

Structure divrec-history backfill coverage as of the last check: 11% of 1419 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 (1982–2026)

Mass-balance kinks computed for every summer month back to 1982 (103 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.

• LAKE FORK AT GATEVIEW, CO.: reach shifted from +365 cfs to +213 cfs summer mean (more losing, p=0.005, 16 yr) [mountain crystalline canyon: minimal groundwater storage -- large or shifting unaccounted losses here are more consistent with data/measurement issues or unmodeled plumbing than with aquifer exchange]

Groundwater now has its own tab: 19 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 1975, click-to-chart histories.

Cross-gage pattern fingerprint

Over the 11-year window with full coverage (2016–2026), the dominant shared pattern across 3 gage(s) explains 89% 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.

Structures most implicated by reconciliation (as of 2026-07-06)

Which structures' data absorbed the most correction when the current mass-balance snapshot was reconciled -- see the Historical tab for the full picture on any date.

• SAN CRISTOBAL PL NO 2 (diversion): +0.1 cfs (0% of that reach's correction)
• MARVAN WATERLINE (diversion): +0.1 cfs (0% of that reach's correction)
• VAN & MARTHA PL SYSTEM (diversion): +0.1 cfs (0% of that reach's correction)
• IRVIN BUSCHBAUM PL (diversion): +0.1 cfs (0% of that reach's correction)
• HOTCHKISS SPRING PL (return): +0.1 cfs (0% of that reach's correction)
• WRIGHT SPRING PIPELINE (return): +0.1 cfs (0% of that reach's correction)
• BARKER DITCH (diversion): +0.1 cfs (0% of that reach's correction)
• WILLIAMS DITCH (diversion): +0.1 cfs (0% of that reach's correction)
• CONTENTION DITCH (diversion): +0.1 cfs (0% of that reach's correction)
• GLADIATOR PIPELINE (diversion): +0.1 cfs (0% of that reach's correction)

Source DWR administrative record · verify at DWR groundwater wells ↗ Source DWR administrative record · verify at DWR well permits ↗

43 water-level measurements across 19 monitored well(s) — 18 alluvial, 0 bedrock — plus 0 administered well(s) reporting metered pumping.

Well map

3D aquifer x-ray

Every aquifer unit as its own head surface, animated through time.

Water-table trends

Of 0 well(s) with enough record for a trend test: 0 declining, 0 rising.

Stream corridors — the surface connection

Where a reach's gain or loss has shifted, the wells within two miles of its anchoring gage and what their water table did over the same era.

LAKE FORK AT GATEVIEW, 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.

Source DWR administrative record · verify at DWR structure records ↗

9 reservoir(s) with 7,860 storage measurement(s), 1975–2026. Basin storage as of 2025-10-31 (the record's own end — reservoir records publish ~annually): 128,266 AF across 3 reservoir(s).

Reservoir map — how full is each vessel?

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 row to chart its full storage history, or open its dossier for rights, documents and dam-safety facts.

Source Independent agency measurement · fetched 2026-09-14 · verify at NRCS report generator ↗ Source Our computation, scored against a reference · NRCS forecast, graded here against the gage record

Snow-water equivalent, WY2026

No snow on the ground — normal for the date; the snow year begins in October. The chart shows the full water year just ending.

NRCS SNOTEL, daily. Sites are assigned to the district whose boundary contains them — the snow that feeds this district can also sit in a neighboring headwater district.

Two ways a snow year goes wrong (1981–2026)

A bad snow year here comes in two flavors (both called snow droughtA winter that shorts the snowpack. It happens two ways: a dry one, where the snow never comes, and a warm one, where near-normal snow falls but melts off weeks early -- and the river feels them differently.), and the river feels them differently. In 7 of the last 46 winters the snow never came — the pack peaked below 80% of its median. In 0 more, the snow came but left early — a near-normal peak melted out two weeks or more ahead of its usual date, sending the water down before the season needed it. This year was one of the dry ones: the pack peaked at 44% of median.

The snow never came: 1981, 1988, 1992, 2002, 2018, 2022, 2026.

Computed by this site from 2 SNOTEL sites’ full daily records (NRCS AWDB, back to 1981). Each year is measured against each site’s own multi-decade median — not the 1991–2020 normal the chart above uses — so the 1980s grade against a fair baseline. Peak and melt-out need 85% of the season’s days on the record; thin years are dropped, not guessed. Derived from snow measurements alone — it cannot tell dry-from-warm causes apart, only what the snowpack did.

Runoff outlook — Lake Fk at Gateview

NRCS's final issue (2026-06-01) calls it even odds that at least 17 kAF arrives over 06-01 to 07-31 — 24% of a normal season; almost certainly at least 8, probably not more than 30. Our own record at this gage shows 12 kAF actually delivered (partial record: 36 of 61 days). New forecasts begin in January. How to read these numbers →

How good are these forecasts here? (1995–2025)

Grading every April issue against what the river then delivered, measured at this gage’s own record — 30 seasons: the median miss of the 50% forecast is 11%, with a high bias of 1%, and the observed volume landed inside the stated 10–90% band 87% of the time (a calibrated forecast would say 80%).

Computed by this site: NRCS's archived April issues (their period as issued each year) against the observed volume in DWR’s published record; years with under 90% daily coverage are dropped, not summed. A grade of the forecast, never of the forecasters — these are hard rivers. How this point ranks among every graded Colorado forecast point →

What April snow has meant for this river (1981–2025)

Across 45 measured years, the season’s water has closely followed the April snowpack: a year opening April with 80% of median snow has typically gone on to deliver about 72% of a normal season (a snow-to-runoff elasticityHow strongly one number moves with another. A snow-to-runoff elasticity of 1.5 means a 10% shortfall in April snowpack has typically become a 15% shortfall in the season's water. of 1.2).

Computed by this site: the district’s April 1 SWE (% of each SNOTEL site’s own-record median) against the observed April–July volume at this gage (% of its median season) — a fixed window every year, unlike the forecast grades above, which use each issue’s own period. The slope is fit so single wild years can’t steer it (Theil–Sen, log space); years missing 10% of their days are dropped.

Source Our computation, no independent reference · computed here from the screened DWR record Source Independent agency measurement · fetched 2026-09-08 · verify at U.S. Drought Monitor ↗

Right now

This is the 22nd-driest week 27 in 116 years of record at GUNNISON RIVER BELOW GUNNISON TUNNEL, CO (as of 2026-06-29; this week’s flow sits at the 19th percentileRank against the record: a river at its 5th percentile is lower than it was in 95 of the past 100 years on this same date. for the date). On this week’s US Drought Monitor, Gunnison County is 50% in D4 exceptional drought (2026-09-08). The law agrees: the most senior active call leaves 0% of this district’s decreed flow rights junior to the calling right this week.

Every year since 1910, week by week

Each thin row is a year at GUNNISON RIVER BELOW GUNNISON TUNNEL, CO; each cell is one week’s flow ranked against the same calendar week of every other year — warm means dry for the date, blue wet, so seasonality cancels and droughts appear as warm bands. Gaps are missing record, never a dry river. Click a year to reconstruct it on the Historical tab.

This year against its analogs

Over the 27 weeks recorded so far, 2026’s weekly trace most resembles 2013 (mean gap 5.7 percentile points; next closest 1989 (8.4), 1990 (8.5)). The analog’s remainder is drawn as context — its ending is what happened to it, not a forecast for this year.

The Drought Monitor’s view since 2000

Mean share of area in each class across Gunnison, Hinsdale, Montrose counties — the counties this district’s gages sit in, which overlap the district imperfectly. The Drought Monitor weighs soils, vegetation and local reports; it is CONTEXT beside the river’s own record above, not the water-rights picture.

The law’s own drought gauge

When water runs short, administration answers: calls reach further back in time, and more decreed rights go junior to the calling right. This is that response, weekly since 2002 — the share of this district’s decreed flow rights junior to the most senior active call. Watch it spike in the named droughts below, and linger after the river recovers.

Computed from DWR’s call record (32 calls touching this district) against the district’s rights index. Scoping is deliberately coarse — a call’s own district, or districts named in its comments — and this is administration’s RESPONSE, not a per-structure verdict (each dossier’s curtailment card does that, with stream miles). A deepening call can also reflect growing demand, not only shrinking supply.

This basin’s droughts, by its own record

Detected mechanically: the 26-week smoothed percentile below the 30th for at least 20 weeks; recovered on regaining the 50th. The water-table clock compares each monitoring well against its own pre-drought median (the 3 years before onset) and dates the year the median well got back — the aquifer remembers longest, and “still below” is a finding, not a gap. The knobs are stated because the episode list depends on them — a different reasonable choice merges or splits episodes at the edges. Names are attached where an episode overlaps a drought Colorado already talks about.

When this basin claimed its water

Every bar is a year’s new appropriations (1,848 rights across 117 years of shared record), colored by that year’s wetness from the barcode above. Here the correlation is +0.06 — essentially no wet-dry pattern; here, law and settlement set the pace, not the weather. Across the state both behaviors exist: ephemeral southwest basins file after wet demonstrations, transbasin-source basins under drought — and the biggest statewide filing waves sat in the 1950s drought and after 2002, not in the wet 1980s–90s.

Appropriation dates are the CLAIMED initiation of a right, not the courthouse filing date; the record is survivor-biased (abandoned claims are absent, so failed dry-era scrambles are undercounted); and the big 1960s and 2000s spikes sit on legal events — the pre-1969-Act adjudication era and 2000s legislation — not on weather. A correlation here is a description, never a cause.

New to how a dry winter becomes a call on the river? Anatomy of a drought walks the chain in four minutes — snow to rivers to reservoirs to calls to the water table.

Who serves it, who protects it

Two registers the site fetches on their own schedules, read for this district. Neither is a DWR record; each links its own page and its agency.

Public water systems here

Source Register of another agency · fetched 2026-09-08 · verify at EPA SDWIS ↗

4 systems touch this district (4 community systems reporting 1,420 people served, a figure that counts a wholesaler's customers twice); 2 of them carry an open health-based violation on EPA's record.

Instream-flow rights held by the state

Source Register of another agency · fetched 2026-09-13 · verify at CWCB instream flow program ↗

83 reaches over 532.9 miles and 12 natural lake levels, held by the Colorado Water Conservation Board so that water stays in the stream. Every reach, with its schedule and case →

• Lake Fork, 30.3 mi: 25 (10/1 - 4/30), 45 (5/1 - 9/30) cfs (appropriated 1980, 80CW0119) · dossier
• Gunnison River, 28.9 mi: 300 (1/1 - 12/31) cfs (appropriated 1965, 92CW0107) · dossier
• Willow Creek, 17.4 mi: 2 (1/1 - 12/31) cfs (appropriated 1980, 80CW0126) · dossier
• Little Cimarron River, 16.4 mi: 2 (1/1 - 12/31) cfs (appropriated 1984, 84CW0396) · dossier
• Lake Fork, 16.0 mi: 20 (10/1 - 4/30), 35 (5/1 - 9/30) cfs (appropriated 1980, 80CW0097) · dossier
• Rock Creek, 13.7 mi: 0.75 (10/1 - 4/30), 3 (05/1 - 9/30) cfs (appropriated 1992, 92CW0173) · dossier

and 89 more on the district's instream-flow page.

What the water is like -- USGS sensors right now, where it has been sampled, the impaired-waters list, and how the tap water here stands with EPA -- is on the Water quality tab.

Designated groundwater basins are on their own page.

Source Adjudicated record · verify at DWR water-right transactions ↗ Source Adjudicated record · verify at DWR net amounts ↗

Decreed rights on this network run from 1872-06-08 to 2025-06-30. Of the 20 structures with a yield estimate, the median one’s senior right was in priority 4% of a median irrigation season and 0% in a dry one. 25 abandonment screens and 179 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: 2280 across 1980 structure(s); 217 structure(s) carry 0 court-case references. Advisory reading aids on public DWR data — not administrative or legal conclusions.

Is the river getting harder to divert from?

Over 2003–2025, administration on this district has been tightening: 1 of 3 measures (days under callA senior water right demanding its water, which requires everyone junior on that stream to stop diverting until it is satisfied., calls set, seniorityColorado shares water by date: the earlier the right, the stronger its claim when the river runs short. "First in time, first in right." of the controlling call) are moving toward more administration, none the other way.

Why diversions stopped — call-based explanations

Sustained diversion stops matched to senior administrative calls.

• BIG BLUE DITCH (6200528) DWR↗☆ stopped 2025-07-27 (58+ days) — call at MINNESOTA CANAL curtailing 100% of its decreed rate [heuristic-strong]
• BIG BLUE DITCH (6200528) DWR↗☆ stopped 2024-11-01 (200+ days) — call at TRANSFER DITCH curtailing 67% of its decreed rate [heuristic-partial]
• ANTONIO FERRARO D NO 1 (6200508) DWR↗☆ stopped 2024-10-30 (334+ days) — call at TRANSFER DITCH curtailing 100% of its decreed rate [heuristic-strong]
• CARSON CREEK NO 2 D (6200551) DWR↗☆ stopped 2024-10-30 (320+ days) — call at TRANSFER DITCH curtailing 100% of its decreed rate [heuristic-strong]
• CHILDS PARK DITCH (6200559) DWR↗☆ stopped 2024-10-30 (279+ days) — call at TRANSFER DITCH curtailing 100% of its decreed rate [heuristic-strong]
• B AND B DITCH (6200519) DWR↗☆ stopped 2024-09-09 (394+ days) — call at MINNESOTA CANAL curtailing 100% of its decreed rate [heuristic-strong]
• BANDIT DITCH (6200545) DWR↗☆ stopped 2024-08-13 (408+ days) — call at MINNESOTA CANAL [heuristic-strong]
• CEBOLLA CREEK DITCH (6200553) DWR↗☆ stopped 2024-08-13 (408+ days) — call at MINNESOTA CANAL curtailing 100% of its decreed rate [heuristic-strong]
• BROWNING DITCH (6200536) DWR↗☆ stopped 2024-08-11 (44+ days) — call at MINNESOTA CANAL curtailing 76% of its decreed rate [heuristic-partial]
• CARR IRRIGATING DITCH (6200548) DWR↗☆ stopped 2024-07-24 (418+ days) — call at PRESTON DITCH curtailing 100% of its decreed rate [heuristic-strong]
• BIG DITCH (6200529) DWR↗☆ stopped 2024-07-23 (401+ days) — call at PRESTON DITCH curtailing 82% of its decreed rate [heuristic-partial]
• BRUCE FRANKLIN DITCH (6200537) DWR↗☆ stopped 2024-07-23 (370+ days) — call at PRESTON DITCH curtailing 100% of its decreed rate [heuristic-strong]

Right yield — how often could these rights actually divert?

Share of irrigation-season days each structure's rights were not called out, derived from the 22-year district-scoped call record (senior right = floor, junior right = ceiling constraint). Call-record-derived; DWR's own analysis governs where available.

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 ~1986 — idleness that begins before then may be unreported use, not nonuse (flagged † below).

• MAURER TOPLISS DRAW D (6200668) DWR↗☆ (1913-05-01, 2.0 cfs decreed): last active 1974 — 50 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1986) -- early absence of record is weak evidence of nonuse
• FISH CREEK RES NO 1 (6203538) DWR↗☆ (1904-07-06, 0.0 cfs decreed): last active 1974 — 50 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1986) -- early absence of record is weak evidence of nonuse
• AUSTIN SPRING NO 2 DITCH (6200514) DWR↗☆ (1928-06-10, 0.0 cfs decreed): last active 1981 — 43 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1986) -- early absence of record is weak evidence of nonuse
• CEBOLLA CREEK (6200579) DWR↗☆ (1980-09-09, 4.0 cfs decreed): last active 1982 — 42 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1986) -- early absence of record is weak evidence of nonuse
• ORME DITCH NO 1 (6200700) DWR↗☆ (1947-06-01, 2.0 cfs decreed): last active 1986 — 38 years idle
• ORME DITCH NO 2 (6200701) DWR↗☆ (1948-06-09, 1.5 cfs decreed): last active 1986 — 38 years idle
• ORME DITCH NO 3 (6200702) DWR↗☆ (1948-06-09, 0.5 cfs decreed): last active 1986 — 38 years idle
• HOFMANN SPG & DOM PL (6200984) DWR↗☆ (1950-06-15, 0.2 cfs decreed): last active 1987 — 37 years idle
• HOFMANN SPG NO 5 & PL (6200985) DWR↗☆ (1971-09-15, 0.0 cfs decreed): last active 1987 — 37 years idle
• BRUTON DITCH NO 1 (6200538) DWR↗☆ (1912-07-01, 0.8 cfs decreed): last active 1989 — 35 years idle

Compliance screens (179 advisory flags)

Screened 257 of 1980 structures with rights (274 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.

• GUNNISON TUNNEL AND SOUTH CANAL (6200617) DWR↗☆: Observed p99 daily rate 1351.0 cfs (max 2672.0) exceeds total decreed absolute 1175.0 cfs across 26883 recorded day(s).
• BIG DITCH (6200529) DWR↗☆: Observed p99 daily rate 48.2 cfs (max 51.6) exceeds total decreed absolute 33.0 cfs across 6770 recorded day(s).
• FRANK ADAMS D NO 2 (6200605) DWR↗☆: Observed p99 daily rate 48.0 cfs (max 53.9) exceeds total decreed absolute 38.5 cfs across 9646 recorded day(s).
• BROWNING DITCH (6200536) DWR↗☆: Observed p99 daily rate 44.0 cfs (max 53.2) exceeds total decreed absolute 6.0 cfs across 8258 recorded day(s).
• COOPER NO 2 D (6200569) DWR↗☆: Observed p99 daily rate 44.0 cfs (max 59.1) exceeds total decreed absolute 26.5 cfs across 8044 recorded day(s).
• GEORGE ANDREWS NO 1 D (6200612) DWR↗☆: Observed p99 daily rate 42.6 cfs (max 42.6) exceeds total decreed absolute 13.6 cfs across 7926 recorded day(s).
• M B & A DITCH (6200670) DWR↗☆: Observed p99 daily rate 37.0 cfs (max 41.2) exceeds total decreed absolute 27.8 cfs across 7582 recorded day(s).
• MCKINLEY DITCH (6200672) DWR↗☆: Observed p99 daily rate 36.0 cfs (max 38.0) exceeds total decreed absolute 31.0 cfs across 17757 recorded day(s).
• SOUTH BEAVER CREEK DITCH (6200754) DWR↗☆: Observed p99 daily rate 35.5 cfs (max 35.5) exceeds total decreed absolute 0.8 cfs across 3842 recorded day(s).
• YOUMANS IRG D NO 1 (6200809) DWR↗☆: Observed p99 daily rate 34.3 cfs (max 47.8) exceeds total decreed absolute 0.3 cfs across 3318 recorded day(s).

Seniority (top structures by decreed rate)

Recent inventory & legal-document changes

• 2026-09-04 — call set: GALLOWAY DITCH (39410)
• 2026-09-04 — call released: 39314
• 2026-09-03 — call set: PAONIA DITCH (39405)
• 2026-09-03 — call set: CRAWFORD CLIPPER DITCH (39401)
• 2026-09-03 — call released: 39364
• 2026-09-03 — call released: 39310

Water-court filings this month (division-wide)

15 applications in the 2026-08 resume for this basin's division — new rights, changes, augmentation plans — from the water clerk's statutory monthly notice (C.R.S. 37-92-302), the earliest public signal of a new claim. Filings are division-wide, not district-filtered: check the county column. Full resume PDF at the Judicial Branch →

Anyone affected may file a statement of opposition until 2026-10-31 (46 days left). C.R.S. 37-92-302(3): due by the last day of the second month following the filing month — computed, not legal advice; confirm with the water clerk.

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.