Culebra Creek

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 2026-10-23 (the newest reading on file), flows at the 18 ranked gages are running at a median 109% of their own long-term norm for this window — 4 below a typical year, 14 at or above. Driest relative to its record: COSTILLA CREEK NEAR GARCIA, CO, ranking 1st lowest of 17 years.

Gage flow trend & changepoints

Of the 21 gages with enough record, 3 are trending down and 0 up, and 3 carry a detected shift. The clearest is Culebra Creek below San Luis, its annual mean flow changing -30.93 cfs per decade (-45.5% of its median annual flow) over 16 years (p=0.0014). The other 17 show no clear signal either way.

⚠️ 1 gage flagged: their records may have quietly shifted against their neighbours, so treat their trends with caution.

17 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. 18 gage(s) and 94 structure(s) report in 2026, but structure reporting only reached half its modern level around ~1952. 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: 16% of 490 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 (108 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.

• CULEBRA CREEK AT SAN LUIS, CO: reach shifted from -3 cfs to +21 cfs summer mean (more gaining, p=0.022, 26 yr) [alluvial valley: real alluvial aquifer -- a decades-long shift toward losing is the classic signature of alluvial pumping and urbanization] [measurement-evolution caution: this shift co-moves with the growth of the gage/metering network (rho=0.59) -- part of it may be unaccounted water becoming accounted, not hydrologic change]

Groundwater now has its own tab: 53 monitored well(s), water-table trends, stream corridors, and the advisory depletion screen.

Reservoirs now has its own tab: 5 reservoir(s), end-of-year storage back to 1963, click-to-chart histories.

Cross-gage pattern fingerprint

Over the 15-year window with full coverage (2012–2026), the dominant shared pattern across 3 gage(s) explains 69% 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 2026-10-23)

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.

• ROMERO D (diversion): -19.2 cfs (100% of that reach's correction)
• SAN LUIS PEOPLES D (diversion): -6.6 cfs (100% of that reach's correction)
• GUADALUPE SANCHEZ D (diversion): -3.9 cfs (20% of that reach's correction)
• PANDO D (diversion): -3.9 cfs (20% of that reach's correction)
• CULEBRA SANCHEZ CANAL (diversion): -3.9 cfs (20% of that reach's correction)
• CULEBRA SANCHEZ CANAL DIVERSION MEASUREM (diversion): -3.9 cfs (20% of that reach's correction)
• CERRO D (diversion): -3.9 cfs (20% of that reach's correction)
• FRANCISCO SANCHEZ D (diversion): +3.2 cfs (17% of that reach's correction)
• CULEBRA EASTDALE D (diversion): +3.2 cfs (17% of that reach's correction)
• CULEBRA CERRITOS CANAL (diversion): +3.2 cfs (17% of that reach's correction)

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

4,539 water-level measurements across 53 monitored well(s) — 8 alluvial, 7 bedrock — plus 5 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 23 well(s) with enough record for a trend test: 10 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.

Source DWR administrative record · verify at DWR structure records ↗

5 reservoir(s) with 8,268 storage measurement(s), 1963–2026. Basin storage as of 2025-10-31 (the record's own end — reservoir records publish ~annually): 2,510 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 2026-11-05 · verify at NRCS report generator ↗ Source Our computation, scored against a reference · NRCS forecast, graded here against the gage record

Snow-water equivalent, WY2027

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 (1980–2026)

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 14 of the last 47 winters the snow never came — the pack peaked below 80% of its median. In 1 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.

The snow never came: 1981, 1986, 1988, 1996, 1999, 2002, 2006, 2011, 2012, 2013, 2018, 2022, 2025, 2026. The snow left early: 1989.

Computed by this site from 1 SNOTEL site’ full daily records (NRCS AWDB, back to 1980). 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 — Culebra Ck at San Luis

NRCS's final issue (2026-06-01) calls it even odds that at least 2 kAF arrives over 06-01 to 09-30 — 22% of a normal season; almost certainly at least 1, probably not more than 6. Our own record at this gage shows 5 kAF actually delivered. New forecasts begin in January. How to read these numbers →

The record-adjusted April benchmark

NRCS’s April issue (2026-04-01) called even odds at 2 kAF over 04-01 to 09-30. Re-anchoring that number on this river’s own history — how its April issues have verified, the winter’s baseflow, and the district’s April 1 snowpack — moves it to 6 kAF. The river delivered 6 kAF.

Computed by this site — not an NRCS number, and shown only because it earned it: replayed over 62 past seasons here (1962–2025), never seeing the year it predicts, the adjustment cut the typical April miss from 24% to 20%. At points where it does not beat NRCS, no adjusted number appears. Coefficients are frozen each August; the model never changes mid-season. Method and honest limits →

How good are these forecasts here? (1950–2026)

Grading every April issue against what the river then delivered, measured at this gage’s own record — 75 seasons: the median miss of the 50% forecast is 26%, with a high bias of 3%, and the observed volume landed inside the stated 10–90% band 91% 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 (1980–2026)

Across 47 measured years, April snowpack has explained only part of this river’s season — the dots below scatter widely, so read any single year’s snow number loosely here. In warm, early-melt years the river delivered a median of 129% of a normal season, against 95% in typical years — the timing of the melt matters, not just its size.

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 2026-10-27 · verify at U.S. Drought Monitor ↗

Right now

This is the 73rd-driest week 43 in 100 years of record at CULEBRA CREEK AT SAN LUIS, CO (as of 2026-10-19; this week’s flow sits at the 73rd 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, Costilla County is 92% in D1 moderate drought (2026-10-27). The law agrees: the most senior active call leaves 20% of this district’s decreed flow rights junior to the calling right this week.

Every year since 1927, week by week

Each thin row is a year at CULEBRA CREEK AT SAN LUIS, 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 43 weeks recorded so far, 2026’s weekly trace most resembles 1977 (mean gap 13.3 percentile points; next closest 1951 (14.1), 2022 (16.6)). 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 Costilla county — 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 2015 — 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 (1367 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 (306 rights across 100 years of shared record), colored by that year’s wetness from the barcode above. Here the correlation is -0.08 — 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 2026-10-06 · verify at EPA SDWIS ↗

5 systems touch this district (5 community systems reporting 1,375 people served, a figure that counts a wholesaler's customers twice); none carries an open health-based violation on EPA's record.

Instream-flow rights held by the state

Source Register of another agency · fetched 2026-11-01 · verify at CWCB instream flow program ↗

The Board's tabulation lists no instream-flow reach or natural lake level in this district. Statewide →

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 1852-04-10 to 2000-05-04. Of the 20 structures with a yield estimate, the median one’s senior right was in priority 32% of a median irrigation season and 0% in a dry one. 3 abandonment screens and 48 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: 541 across 453 structure(s); 69 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 1969–2025, administration on this district has been tightening: 3 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.

• CHOURY D (2400527) DWR↗☆ stopped 2025-10-19 (12+ days) — call at SANGRE CRISTO TRINCHERA curtailing 100% of its decreed rate [heuristic-strong]
• CHOURY D (2400527) DWR↗☆ stopped 2025-09-28 (7+ days) — call at RIO GRANDE COMPACT - LOBATOS curtailing 100% of its decreed rate [heuristic-strong]
• CHOURY D (2400527) DWR↗☆ stopped 2025-08-31 (14+ days) — call at RIO GRANDE COMPACT - LOBATOS curtailing 100% of its decreed rate [heuristic-strong]
• CULEBRA EASTDALE D (2400533) DWR↗☆ stopped 2025-08-29 (9+ days) — call at RIO GRANDE COMPACT - LOBATOS curtailing 100% of its decreed rate [heuristic-strong]
• CHOURY D (2400527) DWR↗☆ stopped 2025-08-08 (9+ days) — call at RIO GRANDE COMPACT - LOBATOS curtailing 100% of its decreed rate [heuristic-strong]
• CULEBRA CERRITOS CANAL (2400532) DWR↗☆ stopped 2025-08-04 (10+ days) — call at RIO GRANDE COMPACT - LOBATOS curtailing 100% of its decreed rate [heuristic-strong]
• J M J MAEZ D (2400553) DWR↗☆ stopped 2025-06-29 (113+ days) — call at RIO GRANDE COMPACT - LOBATOS curtailing 54% of its decreed rate [heuristic-partial]
• ABAN SANCHEZ D (2400502) DWR↗☆ stopped 2025-06-28 (103+ days) — call at RIO GRANDE COMPACT - LOBATOS curtailing 100% of its decreed rate [heuristic-strong]
• ALBERT AND VIGIL D (2400509) DWR↗☆ stopped 2025-06-28 (125+ days) — call at RIO GRANDE COMPACT - LOBATOS curtailing 100% of its decreed rate [heuristic-strong]
• ANTONIO VALDEZ D (2400512) DWR↗☆ stopped 2025-06-28 (118+ days) — call at RIO GRANDE COMPACT - LOBATOS curtailing 100% of its decreed rate [heuristic-strong]
• ANTONIO SANCHEZ D (2400513) DWR↗☆ stopped 2025-06-28 (117+ days) — call at RIO GRANDE COMPACT - LOBATOS curtailing 100% of its decreed rate [heuristic-strong]
• GUADALUPE SANCHEZ D (2400550) DWR↗☆ stopped 2025-06-28 (124+ days) — call at RIO GRANDE COMPACT - LOBATOS 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 (3 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 ~1952 — idleness that begins before then may be unreported use, not nonuse (flagged † below).

• ABUNDO MARTINEZ D (2400609) DWR↗☆ (1874-05-31, 1.8 cfs decreed): last active 1963 — 25 years idle
• VEGA D (2400597) DWR↗☆ (1905-07-03, 0.7 cfs decreed): last active 1973 — 15 years idle
• CERRO CNL (2400521) DWR↗☆ (1853-01-01, 5.5 cfs decreed): last active 1976 — 12 years idle

Compliance screens (48 advisory flags)

Screened 84 of 453 structures with rights (92 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.

• CERRO CNL (2400521) DWR↗☆: Observed p99 daily rate 42.8 cfs (max 48.0) exceeds total decreed absolute 5.5 cfs across 710 recorded day(s).
• VEGA D (2400597) DWR↗☆: Observed p99 daily rate 12.0 cfs (max 12.0) exceeds total decreed absolute 0.7 cfs across 730 recorded day(s).
• A A SALAZAR D 1 (2400500) DWR↗☆: Observed p99 daily rate 10.5 cfs (max 20.0) exceeds total decreed absolute 3.0 cfs across 3191 recorded day(s).
• ALFONSO DITCH (2400510) DWR↗☆: Observed p99 daily rate 10.0 cfs (max 10.0) exceeds total decreed absolute 3.0 cfs across 4850 recorded day(s).
• QUATES D 1 (2400573) DWR↗☆: Observed p99 daily rate 10.0 cfs (max 27.6) exceeds total decreed absolute 2.5 cfs across 32572 recorded day(s).
• QUATES D 2 (2400574) DWR↗☆: Observed p99 daily rate 10.0 cfs (max 30.0) exceeds total decreed absolute 1.5 cfs across 11026 recorded day(s).
• GARCIA D (2400549) DWR↗☆: Observed p99 daily rate 6.8 cfs (max 22.0) exceeds total decreed absolute 1.0 cfs across 11148 recorded day(s).
• ACEQUIA MADRE D (2400506) DWR↗☆: Observed p99 daily rate 6.0 cfs (max 10.5) exceeds total decreed absolute 5.0 cfs across 18230 recorded day(s).
• RUMALDO GALLEGOS DITCH (2400630) DWR↗☆: Observed p99 daily rate 5.9 cfs (max 5.9) exceeds total decreed absolute 0.6 cfs across 516 recorded day(s).
• CHOURY D (2400527) DWR↗☆: Observed p99 daily rate 5.7 cfs (max 8.0) exceeds total decreed absolute 3.9 cfs across 21584 recorded day(s).

Seniority (top structures by decreed rate)

Recent inventory & legal-document changes

• 2026-11-01 — call set: CHICAGO D (39837)
• 2026-11-01 — call set: RIO GRANDE COMPACT - LOBATOS (39838)
• 2026-11-01 — call released: 39820
• 2026-10-30 — call set: CHICAGO D (39820)
• 2026-10-30 — call released: 39768
• 2026-10-28 — call set: HUGHES D 1 (39804)
• 2026-10-28 — call set: SEYFRIED STRIBLING D (39805)
• 2026-10-28 — call released: 39796

Water-court filings this month (division-wide)

2 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 →

The statement-of-opposition window for these filings closed 2026-10-31. 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.

Active substitute water supply plans in this district

Temporary State Engineer approvals to divert out of priority (37-92-308 / 37-90-137). A structure operating under one behaves differently under a call than its decreed rights alone suggest — the priority tables above don't know about these; this list does. Source: DWR’s active-SWSP register, refreshed nightly.

The water itself, in this district

Four registers, each on its own schedule: what USGS sensors read right now, where samples have been taken, which stretches the state lists as impaired, and how the tap water of the systems here stands with EPA. None is a DWR record; each links its own page.

Right now

Source Provisional telemetry · fetched 2026-11-04 · verify at USGS current conditions ↗

No USGS continuous water-quality sensor reports from inside this district. Statewide sensors →

Where water has been sampled

Source Register of another agency · fetched 2026-10-08 · verify at Water Quality Portal ↗

The portal lists 866 sampling stations in this district's watersheds (Alamosa-Trinchera 13010002, 76% of the district; Upper Rio Grande 13020101, 23% of the district), of which 34 reported a sample in the last 5 years on the state and tribal side (USGS activity is in the station count, not in that figure). Most active: Colorado Dept. of Public Health & Environment-WQCD (21), Colorado River Watch (12), USGS Colorado Water Science Center (1). Most-sampled groups: Inorganics, Major, Metals, Physical, Nutrient, Inorganics, Minor, Metals. Every station as a file ↗

Results themselves are not fetched here; USGS samples added after March 2024 may not be in the portal's legacy profiles yet.

Drinking water

Source Register of another agency · fetched 2026-10-07 · verify at EPA SDWIS ↗

5 community systems touch this district. None carries an open health-based violation on EPA's record. EPA sampled 0 of them for PFAS in 2023–25.

EPA's record carries violations and lead/copper percentiles; nitrate and disinfection by-product results are not in it. UCMR 5 samples are monitoring, not compliance, and the 2024 PFOA/PFOS limits equal its reporting limit, so any detection of those two is at or above them.

Impaired waters

Source Register of another agency · verify at EPA ATTAINS ↗

The state's 303(d) impaired-waters list has not been joined to this basin's own watershed boundary yet, so nothing is shown rather than a guess; the basins with a join carry the full list here. Why the join is geometry, not a name match.