McElmo Creek Basin

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 2026-09-27 (the newest reading on file), flows at the 7 ranked gages are running at a median 5% of their own long-term norm for this window — 7 below a typical year, 0 at or above. Driest relative to its record: DOVE CREEK CANAL BELOW GREAT CUT DIKE, ranking 1st lowest of 32 years.

Gage flow trend & changepoints

Of the 16 gages with enough record, 4 are trending down and 0 up, and 6 carry a detected shift. The clearest is U Lateral Canal below Great Cut Dike near Dolores, its annual mean flow changing -3.82 cfs per decade (-12.6% of its median annual flow) over 29 years (p<0.0001). The other 10 show no clear signal either way.

Drought history, cost, and the four-century context moved to the Drought tab.

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

10 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. 10 gage(s) and 182 structure(s) report in 2026, but structure reporting only reached half its modern level around ~1980. 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: 58% of 398 schematic-relevant structures. Kink count trend: no_trend (p=0.115), kink magnitude trend: no_trend (p=0.119) across 45 qualifying year(s).

Reach gain/loss shifts (1985–2026)

Mass-balance kinks computed for every summer month back to 1985 (148 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.

• ROCKY FORD CANAL #2 ABOVE TOTTEN RESERVOIR NEAR CORTEZ: reach shifted from -243 cfs to -89 cfs summer mean (more gaining, p=0.043, 24 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=-0.63) -- part of it may be unaccounted water becoming accounted, not hydrologic change]

Groundwater now has its own tab: 22 monitored well(s), water-table trends, stream corridors, and the advisory depletion screen.

Reservoirs now has its own tab: 15 reservoir(s), end-of-year storage back to 1975, click-to-chart histories.

Cross-gage pattern fingerprint

Over the 33-year window with full coverage (1994–2026), the dominant shared pattern across 5 gage(s) explains 61% of year-to-year variance (almost certainly a basin-wide climate/snowpack driver).

MVIDIVCO doesn't move with that shared pattern -- a real, localized signal (a new diversion, land-use change, or a gage-specific data problem) worth a closer look, not necessarily noise.

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

97 water-level measurements across 22 monitored well(s) — 7 alluvial, 0 bedrock — plus 1 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.

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 ↗

15 reservoir(s) with 8,715 storage measurement(s), 1975–2026. Basin storage as of 2025-10-31 (the record's own end — reservoir records publish ~annually): 3,647 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 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 32nd-driest week 42 in 76 years of record at MCELMO CREEK NEAR COLORADO-UTAH STATE LINE (as of 2026-10-12; this week’s flow sits at the 42nd 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, Montezuma County is 5% in D1 moderate drought (2026-10-27). 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 1951, week by week

Each thin row is a year at MCELMO CREEK NEAR COLORADO-UTAH STATE LINE; 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 39 weeks recorded so far, 2026’s weekly trace most resembles 2002 (mean gap 9.8 percentile points; next closest 2018 (11.8), 2021 (12.3)). 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 Montezuma, Montezuma 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 2013 — 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 (198 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.

What drought has cost here

Since 1991, federal crop insurance has paid $1,489,504 in drought-caused claims across Montezuma county — 11.1% of all insured crop losses there. The worst year was 2021 ($338,603).

USDA crop-insurance indemnities where the recorded cause of loss is drought, summed over the counties this district's gages sit in. Counties overlap water districts imperfectly, and insured-crop claims are a floor on drought damage, not a total. Source: USDA RMA cause-of-loss files.

When this basin claimed its water

Every bar is a year’s new appropriations (356 rights across 76 years of shared record), colored by that year’s wetness from the barcode above. Here the correlation is +0.45 — this basin tended to claim water after wet years, when the supply had just shown itself. 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 ↗

6 systems touch this district (6 community systems reporting 24,277 people served, a figure that counts a wholesaler's customers twice); 1 of them 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 ↗

2 reaches over 23.2 miles, held by the Colorado Water Conservation Board so that water stays in the stream. Every reach, with its schedule and case →

• Yellow Jacket Canyon, 12.58 mi: 3.2 (5/16 - 10/31), 2.5 (11/1 - 5/15) cfs (appropriated 2006, 06CW0060) · dossier
• Yellow Jacket Canyon, 10.64 mi: 2.1 (1/1 - 12/31) cfs (appropriated 2006, 06CW0061) · dossier

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 1868-03-02 to 2022-08-05. Of the 20 structures with a yield estimate, the median one’s senior right was in priority 15% of a median irrigation season and 0% in a dry one. 25 abandonment screens and 145 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: 687 across 638 structure(s); 65 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.

• BORD DITCH (3200512) DWR↗☆ stopped 2025-10-14 (10+ days) — call at LA PLATA RIVER BASIN curtailing 100% of its decreed rate [heuristic-strong]
• CHARLES MATTSON DITCH (3200520) DWR↗☆ stopped 2025-09-03 (55+ days) — call at HENRY BOLEN DITCH curtailing 100% of its decreed rate [heuristic-strong]
• DURAN DITCH (3200551) DWR↗☆ stopped 2025-07-10 (21+ days) — call at HENRY BOLEN DITCH curtailing 100% of its decreed rate [heuristic-strong]
• CHARLES MATTSON DITCH (3200520) DWR↗☆ stopped 2025-06-23 (49+ days) — call at LA PLATA RIVER BASIN curtailing 100% of its decreed rate [heuristic-strong]
• BORD DITCH (3200512) DWR↗☆ stopped 2025-06-22 (28+ days) — call at LA PLATA RIVER BASIN curtailing 100% of its decreed rate [heuristic-strong]
• BRIXEY-COMISKY DITCH (3200513) DWR↗☆ stopped 2025-06-22 (58+ days) — call at LA PLATA RIVER BASIN curtailing 100% of its decreed rate [heuristic-strong]
• BURTON DITCH (3200517) DWR↗☆ stopped 2024-10-03 (386+ days) — call at SPRING CREEK DITCH curtailing 100% of its decreed rate [heuristic-strong]
• GAFFORD DITCH NO 2 (3200564) DWR↗☆ stopped 2024-09-10 (15+ days) — call at HENRY BOLEN DITCH curtailing 100% of its decreed rate [heuristic-strong]
• EARL HART DITCH (3200556) DWR↗☆ stopped 2024-09-09 (24+ days) — call at HENRY BOLEN DITCH curtailing 100% of its decreed rate [heuristic-strong]
• HAMBELTON DITCH (3200574) DWR↗☆ stopped 2024-08-12 (6+ days) — call at HENRY BOLEN DITCH curtailing 100% of its decreed rate [heuristic-strong]
• EARL HART DITCH (3200556) DWR↗☆ stopped 2024-08-04 (10+ days) — call at HENRY BOLEN DITCH curtailing 100% of its decreed rate [heuristic-strong]
• COMISKY DITCH NO 1 (3200524) DWR↗☆ stopped 2024-07-24 (461+ days) — call at HENRY BOLEN 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 ~1980 — idleness that begins before then may be unreported use, not nonuse (flagged † below).

• DAWSON DITCH (MCELMO) (3200537) DWR↗☆ (1943-04-25, 1.1 cfs decreed): last active 1974 — 51 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1980) -- early absence of record is weak evidence of nonuse
• MURRAY PUMP AND PIPELINE (3200633) DWR↗☆ (1961-06-30, 0.1 cfs decreed): last active 1974 — 51 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1980) -- early absence of record is weak evidence of nonuse
• PALMER PUMP AND DITCHES (3200639) DWR↗☆ (1920-12-31, 1.0 cfs decreed): last active 1976 — 49 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1980) -- early absence of record is weak evidence of nonuse
• STRATTON DITCH (3200676) DWR↗☆ (1937-06-10, 0.2 cfs decreed): last active 1979 — 46 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1980) -- early absence of record is weak evidence of nonuse
• OLD STAGE STATION DIVR (3200637) DWR↗☆ (1966-12-31, 0.6 cfs decreed): last active 1981 — 44 years idle
• HARMON DITCH ALT PT #1 (3200776) DWR↗☆ (1950-08-19, 0.2 cfs decreed): last active 1983 — 42 years idle
• MURPHY DIVERSION NO 1 (3200751) DWR↗☆ (1978-06-01, 0.5 cfs decreed): last active 1984 — 41 years idle
• FETTERMAN HYDRAM (3200756) DWR↗☆ (1980-04-15, 0.1 cfs decreed): last active 1985 — 40 years idle
• HARMON DITCH SPRUELL #2 (3200578) DWR↗☆ (1950-08-19, 0.1 cfs decreed): last active 1986 — 39 years idle
• CULLEN DITCH (3200535) DWR↗☆ (1900-12-31, 2.5 cfs decreed): last active 1989 — 36 years idle

Compliance screens (145 advisory flags)

Screened 222 of 638 structures with rights (262 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.

• HAMBELTON DITCH (3200574) DWR↗☆: Observed p99 daily rate 16.2 cfs (max 19.0) exceeds total decreed absolute 12.5 cfs across 36288 recorded day(s).
• COTTONWOOD DITCH NO 2 (3200529) DWR↗☆: Observed p99 daily rate 15.0 cfs (max 17.0) exceeds total decreed absolute 10.0 cfs across 33971 recorded day(s).
• BLACK DIKE DITCH (3200509) DWR↗☆: Observed p99 daily rate 13.9 cfs (max 16.9) exceeds total decreed absolute 13.1 cfs across 32347 recorded day(s).
• COTTONWOOD DITCH NO 1 (3200528) DWR↗☆: Observed p99 daily rate 13.5 cfs (max 16.0) exceeds total decreed absolute 10.0 cfs across 26852 recorded day(s).
• ROBERT B DUNHAM DITCH (3200651) DWR↗☆: Observed p99 daily rate 12.6 cfs (max 12.6) exceeds total decreed absolute 3.0 cfs across 2972 recorded day(s).
• EATON DITCH (3200558) DWR↗☆: Observed p99 daily rate 8.4 cfs (max 11.2) exceeds total decreed absolute 6.0 cfs across 19763 recorded day(s).
• MURRAY-ZWICKER-TOZER D (3200634) DWR↗☆: Observed p99 daily rate 8.4 cfs (max 10.3) exceeds total decreed absolute 6.0 cfs across 37422 recorded day(s).
• OLD KANIGA DITCH (3200636) DWR↗☆: Observed p99 daily rate 8.0 cfs (max 8.0) exceeds total decreed absolute 2.0 cfs across 4142 recorded day(s).
• SCHALLES DITCH (3200662) DWR↗☆: Observed p99 daily rate 7.0 cfs (max 8.5) exceeds total decreed absolute 4.0 cfs across 20069 recorded day(s).
• BORD DITCH (3200512) DWR↗☆: Observed p99 daily rate 6.0 cfs (max 7.0) exceeds total decreed absolute 4.0 cfs across 18027 recorded day(s).

Seniority (top structures by decreed rate)

Recent inventory & legal-document changes

• 2026-10-28 — call released: 38819
• 2026-10-28 — call released: 37405
• 2026-10-14 — call released: 38607
• 2026-10-14 — call released: 38820
• 2026-10-14 — call released: 38609
• 2026-10-01 — call released: 39556
• 2026-10-01 — call released: 37181
• 2026-09-30 — call released: 39596

Water-court filings this month (division-wide)

4 applications in the 2026-09 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 2026-11-30 (25 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.

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 ↗

1 USGS sensor reports temperature, conductance, dissolved oxygen or turbidity from inside this district; provisional readings, never merged into the verified record.

Where water has been sampled

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

The portal lists 436 sampling stations in this district's watersheds (McElmo 14080202, 54% of the district; Montezuma 14080203, 32% of the district; Lower San Juan-Four Corners 14080201, 13% of the district), of which 20 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 (9), Ute Mountain Utes Tribe (Colorado) (5), USGS Colorado Water Science Center (3). Most-sampled groups: Inorganics, Minor, Metals, Physical, Inorganics, Major, Metals, Inorganics, Major, Non-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 ↗

6 community systems touch this district. 1 carries an open health-based violation on EPA's record. EPA sampled 2 of them for PFAS in 2023–25; none had PFOA or PFOS at or above the 2024 limit.

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.