San Luis 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 2026-09-27 (the newest reading on file), flows at the 14 ranked gages are running at a median 141% of their own long-term norm for this window — 5 below a typical year, 9 at or above. Driest relative to its record: GARNER CREEK NEAR VILLA GROVE, ranking 2nd lowest of 28 years.

Gage flow trend & changepoints

Of the 20 gages with enough record, 0 are trending down and 0 up, and 1 carries a detected shift. The other 19 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.

19 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. 14 gage(s) and 99 structure(s) report in 2026, but structure reporting only reached half its modern level around ~1969. 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: 20% of 586 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 (479 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: 206 monitored well(s), water-table trends, stream corridors, and the advisory depletion screen.

Cross-gage pattern fingerprint

Over the 28-year window with full coverage (1999–2026), the dominant shared pattern across 11 gage(s) explains 79% of year-to-year variance (almost certainly a basin-wide climate/snowpack driver).

GARVILCO, KERVILCO, MAJVILCO don'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 ↗

19,132 water-level measurements across 206 monitored well(s) — 70 alluvial, 62 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 71 well(s) with enough record for a trend test: 37 declining, 5 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 Our computation, no independent reference · computed here from the screened DWR record Source Independent agency measurement · fetched 2026-10-13 · verify at U.S. Drought Monitor ↗

Right now

This is the 64th-driest week 39 in 91 years of record at CRESTONE CREEK, NORTH NEAR CRESTONE (as of 2026-09-21; this week’s flow sits at the 70th 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, Saguache County is 98% in D3 extreme drought (2026-10-13). The law agrees: the most senior active call leaves 95% of this district’s decreed flow rights junior to the calling right this week.

Every year since 1936, week by week

Each thin row is a year at CRESTONE CREEK, NORTH NEAR CRESTONE; 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 2000 (mean gap 18.8 percentile points; next closest 1956 (21.9), 1996 (22.3)). 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 Saguache 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 2014 — 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 (256 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 2018, federal crop insurance has paid $16,321 in drought-caused claims across Saguache county — 0.0% of all insured crop losses there. The worst year was 2018 ($16,321).

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 (402 rights across 91 years of shared record), colored by that year’s wetness from the barcode above. Here the correlation is +0.11 — 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 ↗

3 systems touch this district (3 community systems reporting 2,879 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 2026-10-18 · verify at CWCB instream flow program ↗

14 reaches over 56.4 miles and 8 natural lake levels, held by the Colorado Water Conservation Board so that water stays in the stream. Every reach, with its schedule and case →

• Kerber Creek, 13.1 mi: 4 (8/1 - 11/15), 2.6 (11/16 - 3/31), 6.75 (4/1 - 7/31) cfs (appropriated 2012, 12CW0036) · dossier
• North Crestone Creek, 7.4 mi: 6.5 (4/15 - 8/31), 3.75 (9/1 - 11/30), 2 (12/1 - 4/14) cfs (appropriated 1994, 94CW0044) · dossier
• Willow Creek, 6.9 mi: 1 (10/1 - 4/14), 1.5 (4/15 - 9/30) cfs (appropriated 1989, 89CW0022) · dossier
• South Crestone Creek, 6.2 mi: 0.5 (10/1 - 4/14), 0.75 (4/15 - 9/30) cfs (appropriated 1989, 89CW0024) · dossier
• Cottonwood Creek, 5.9 mi: 1 (10/1 - 4/14), 2.5 (4/15 - 9/30) cfs (appropriated 1989, 89CW0023) · dossier
• San Isabel Creek, 5.7 mi: 1 (10/1 - 4/14), 3 (4/15 - 9/30) cfs (appropriated 1989, 89CW0016) · dossier

and 16 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 1866-04-01 to 2012-01-24. Of the 20 structures with a yield estimate, the median one’s senior right was in priority 52% of a median irrigation season and 0% in a dry one. 25 abandonment screens and 107 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: 1023 across 847 structure(s); 142 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.

• CHARLES D (2500534) DWR↗☆ stopped 2025-08-19 (27+ days) — call at RIO GRANDE COMPACT - LOBATOS curtailing 100% of its decreed rate [heuristic-strong]
• CHARLES D (2500534) DWR↗☆ stopped 2024-10-29 (182+ days) — call at RIO GRANDE COMPACT - LOBATOS curtailing 100% of its decreed rate [heuristic-strong]
• ALDER CR D (2500502) DWR↗☆ stopped 2024-09-03 (336+ days) — call at RIO GRANDE COMPACT - LOBATOS curtailing 100% of its decreed rate [heuristic-strong]
• CLAYTON OLD CHANNEL DITC (2500557) DWR↗☆ stopped 2024-06-30 (26+ days) — call at RIO GRANDE COMPACT - LOBATOS [heuristic-partial]

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 ~1969 — idleness that begins before then may be unreported use, not nonuse (flagged † below).

• BARSCH D 1 (2500528) DWR↗☆ (1881-04-15, 1.6 cfs decreed): last active 1961 — 64 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1969) -- early absence of record is weak evidence of nonuse
• HOFFMAN D 2 (2500604) DWR↗☆ (1875-05-01, 0.9 cfs decreed): last active 1961 — 64 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1969) -- early absence of record is weak evidence of nonuse
• BACA GRANT 4 IRR D 19 (2500518) DWR↗☆ (1870-05-10, 39.8 cfs decreed): last active 1968 — 57 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1969) -- early absence of record is weak evidence of nonuse
• BRALEY D (2500530) DWR↗☆ (1886-05-09, 1.4 cfs decreed): last active 1973 — 52 years idle
• JOHN DECAMP D B (2500610) DWR↗☆ (1884-06-01, 0.6 cfs decreed): last active 1975 — 50 years idle
• KAUFMAN D (2500611) DWR↗☆ (1883-05-10, 1.0 cfs decreed): last active 1980 — 45 years idle
• DRISCOLL D (2500565) DWR↗☆ (1908-09-28, 1.8 cfs decreed): last active 1984 — 41 years idle
• CEDAR CR D (2500533) DWR↗☆ (1910-03-01, 2.0 cfs decreed): last active 1986 — 39 years idle
• NORTH,MIDDLE & TOP SPGS (2500743) DWR↗☆ (1871-05-01, 1.0 cfs decreed): last active 1989 — 36 years idle
• DRISCOLL D 2 (2500566) DWR↗☆ (1909-04-15, 3.0 cfs decreed): last active 1990 — 35 years idle

Compliance screens (107 advisory flags)

Screened 145 of 847 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.

• BACA GRANT 4 IRR D 9 (2500513) DWR↗☆: Observed p99 daily rate 70.0 cfs (max 90.6) exceeds total decreed absolute 39.0 cfs across 10906 recorded day(s).
• BACA GRANT 4 IRR D 10 (2500514) DWR↗☆: Observed p99 daily rate 41.0 cfs (max 41.0) exceeds total decreed absolute 39.4 cfs across 1308 recorded day(s).
• WALES SHELLABARGER D 2 (2500678) DWR↗☆: Observed p99 daily rate 37.5 cfs (max 54.0) exceeds total decreed absolute 37.0 cfs across 23396 recorded day(s).
• SHELLABARGER HOME D 2 (2500651) DWR↗☆: Observed p99 daily rate 28.0 cfs (max 28.8) exceeds total decreed absolute 3.0 cfs across 476 recorded day(s).
• STEEL D 2 (2500661) DWR↗☆: Observed p99 daily rate 21.5 cfs (max 37.8) exceeds total decreed absolute 7.6 cfs across 28637 recorded day(s).
• BACA GRANT 4 IRR D 3 (2500507) DWR↗☆: Observed p99 daily rate 20.0 cfs (max 30.0) exceeds total decreed absolute 4.0 cfs across 5374 recorded day(s).
• SAN ISABEL D (2500640) DWR↗☆: Observed p99 daily rate 20.0 cfs (max 35.0) exceeds total decreed absolute 19.8 cfs across 5168 recorded day(s).
• BACA GRANT 4 IRR D 5 (2500509) DWR↗☆: Observed p99 daily rate 18.0 cfs (max 29.0) exceeds total decreed absolute 5.8 cfs across 3798 recorded day(s).
• PETERSON D 1 (2500628) DWR↗☆: Observed p99 daily rate 18.0 cfs (max 50.0) exceeds total decreed absolute 14.9 cfs across 15772 recorded day(s).
• BACA GRANT 4 IRR D 4 (2500508) DWR↗☆: Observed p99 daily rate 15.0 cfs (max 22.0) exceeds total decreed absolute 7.0 cfs across 8360 recorded day(s).

Seniority (top structures by decreed rate)

Recent inventory & legal-document changes

• 2026-10-08 — call set: CHICAGO D (39692)
• 2026-10-08 — call released: 39674
• 2026-10-08 — call set: VALDEZ D (39691)
• 2026-10-08 — call released: 39668
• 2026-10-05 — call set: CHICAGO D (39674)
• 2026-10-05 — call released: 39667
• 2026-10-05 — call set: NEWTON D 2 (39673)
• 2026-10-05 — call released: 39639

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 →

Anyone affected may file a statement of opposition until 2026-10-31 (13 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.

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 2026-10-18 · 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 1,500 sampling stations in this district's watersheds (San Luis 13010003; Saguache 13010004, 9% of the district), of which 26 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 (23), Colorado River Watch (2), USGS Colorado Water Science Center (1). Most-sampled groups: Inorganics, Major, Metals, Physical, Nutrient, Inorganics, Minor, 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 ↗

3 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.