Hydrohistorian
San Juan River Basin
Who may take water from the San Juan River Basin, who is calling for it today, and how it is running, compiled from Colorado Division of Water Resources records. Click anything on the map for its record.
San Juan River Basin on the ground — the ditches, wells, reservoirs and gages of Water District 29 · clicktap anything for its record
The well-permit cells in view, as a table
Each row is one ~1-mile cell (0.02°) with the permits the file spots inside it, split into water-supply permits and monitoring holes (DWR’s two monitoring categories: drilled to look at the water, not to pump it). These are permits, not wells: a permit is a piece of paper, and the file does not say which were drilled. Spotting is the file’s own, about a mile at best, which is why the cells are no finer.
| Lat | Lon | Water-supply permits | Monitoring holes |
|---|
Browse this district’s ditches, gages, reservoirs, wells and springs as a list.
The San Juan River is below normal for late September -- 73% of normal flow. 1 call stands against it right now; the most senior right calling dates to 1891. DWR's statements do not settle whether 2 more calls reach it.
Schematic
Historical
Evolution of the network
Trends
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 174% of their own long-term norm for this window — 2 below a typical year, 5 at or above. Driest relative to its record: SAN JUAN RIVER NEAR ARCHULETA, NM, ranking 3rd lowest of 72 years.
How this comparison is made
Each gage's mean flow over the 3 days either side of 2026-09-27, compared with the same window in every year of its own record — so a gage is only ever measured against itself, and gages with no record in the window are counted out rather than guessed.
Gage flow trend & changepoints
What counts as a trend here
Computed 2026-10-11 21:10 from 19 gage(s) with cached period-of-record data. The series is each gage's annual mean flow in cfsCubic feet per second, a rate of flow. One cfs running for a day is about 2 acre-feet. (years with ≥300 days of record). Mann-Kendall (trend, with the Hamed–Rao correction for serial correlation — persistence can otherwise fake significance) and Pettitt (changepoint) both require at least 8 years spanning at least 10 years of record. A gage below that reports no signal — which is not the same as “no change.” The %-per-decade figure is the same Sen slope divided by the gage's median annual flow, for comparing across streams of very different size; it is omitted for near-ephemeral channels where the median is too small to divide by honestly.
Of the 19 gages with enough record, 4 are trending down and 0 up, and 5 carry a detected shift. The clearest is San Juan River near Archuleta, Nm, its annual mean flow changing -82.04 cfs per decade (-10.0% of its median annual flow) over 71 years (p=0.0008). The other 14 show no clear signal either way.
| Gage | Trend | Change / decade cfs · % of median annual flow | Significance | Years | Changepoint |
|---|---|---|---|---|---|
|
▸
San Juan River near Archuleta, Nm SANARCNM |
↓ decreasing | -82.04 cfs -10.0% | p<0.001 | 71 | ~1999 |
|
▸
San Juan River near Carracas SANCARCO |
↓ decreasing | -37.71 cfs -7.3% | p=0.012 | 64 | ~1999 |
|
▸
Rio Blanco below Blanco Diversion Dam near Pagosa RIOBLACO |
↓ decreasing | -2.29 cfs -8.5% | p=0.012 | 55 | ~1998 |
|
▸
San Juan River at Farmington, Nm SANFARNM |
↓ decreasing | -84.88 cfs -5.1% | p=0.014 | 92 | ~1999 |
|
▸
Rio Blanco at the Mouth near Trujillo RIOMOUCO |
no clear trend | -7.09 cfs -12.9% | p=0.050 | 49 | ~1995 |
14 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. 8 gage(s) and 126 structure(s) report in 2026, but structure reporting only reached half its modern level around ~1974. 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) |
|---|---|---|
| 1930s | 4 | 0 |
| 1940s | 8 | 0 |
| 1950s | 7 | 0 |
| 1960s | 7 | 49 |
| 1970s | 9 | 138 |
| 1980s | 8 | 170 |
| 1990s | 8 | 168 |
| 2000s | 8 | 182 |
| 2010s | 8 | 158 |
| 2020s | 8 | 123 |
Mass-balance (network closure) trend
Structure divrec-history backfill coverage as of the last check: 20% of 964 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 (1555 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.
- RIO BLANCO AT THE MOUTH NEAR TRUJILLO: reach shifted from -575 cfs to -343 cfs summer mean (more gaining, p=0.044, 56 yr) [alluvial valley: real alluvial aquifer -- a decades-long shift toward losing is the classic signature of alluvial pumping and urbanization]
Groundwater now has its own tab: 37 monitored well(s), water-table trends, stream corridors, and the advisory depletion screen.
Reservoirs now has its own tab: 67 reservoir(s), end-of-year storage back to 1970, click-to-chart histories.
Cross-gage pattern fingerprint
Over the 65-year window with full coverage (1962–2026), the dominant shared pattern across 3 gage(s) explains 85% 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 2026-09-27)
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.
- R-1812 (diversion): +48.9 cfs (17% of that reach's correction)
- R-1811 (diversion): +48.9 cfs (17% of that reach's correction)
- VELASQUEZ DITCH (diversion): +48.9 cfs (17% of that reach's correction)
- ROSA DITCH (diversion): +48.9 cfs (17% of that reach's correction)
- DARLINGTON WASTE WATER D (diversion): +48.9 cfs (17% of that reach's correction)
- PENINSULA DITCH NO 2 (diversion): +48.9 cfs (17% of that reach's correction)
- PSRC #9 (diversion): +0.6 cfs (1% of that reach's correction)
- COUNTY OUTFLOW #1 (diversion): +0.6 cfs (1% of that reach's correction)
- PSRC #8 (diversion): +0.6 cfs (1% of that reach's correction)
- PSRC SPRING 2000-1 (return): +0.6 cfs (1% of that reach's correction)
Data provenance & quality
Where these numbers come from and how far they can be trusted. Grade C (3/6 points) — the components below are the finding; the letter alone is not. Sources: DWR HydroBase snapshot HydroBase_CO_20260928 (imported 2026-10-04) for history, plus the CDSS REST API for current conditions.
| Check | State | What was measured |
|---|---|---|
| gage freshness | stale | newest gage reading is 14 day(s) old (target 7) |
| diversion record | expected-lag | newest diversion record is 346 day(s) old (DWR publishes ~1 year in arrears) |
| structure coverage | sparse | 20% of schematic structures have data |
Independent check: PASS — 100.0000% agreement across 64,889 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 — 99.87% day-level agreement with USGS's own published records for the same gages, across 16 co-listed station(s) and 207,720 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.
19 gage(s) / 254,977 daily values (1930-10-01–2026-09-27); 349 structure(s) with diversion records; 853 with decreed rights. Methodology has not yet had independent expert review — treat every figure as an advisory screen, not an administrative or legal conclusion.
Groundwater
Source DWR administrative record · verify at DWR groundwater wells ↗ Source DWR administrative record · verify at DWR well permits ↗
97 water-level measurements across 37 monitored well(s) — 23 alluvial, 0 bedrock — plus 12 administered well(s) reporting metered pumping.
What is being counted
Observation wells and pumping wells are different populations and are never conflated: water levels come from monitored observation wells, and metered pumping comes from administered wells reporting through diversion records. Click any well to chart its own record.
Well map
3D aquifer x-ray
Every aquifer unit as its own head surface, animated through time.
How the surfaces are built, and what they are not
Alluvial water table on top, Denver Basin members (Dawson, Denver, Arapahoe, Laramie–Fox Hills) stacked beneath where measured, interpolated from measured water levels. Units are never mixed; a surface exists only inside its own unit's well coverage, with no extrapolation; thin epochs are suppressed and say why. Vertical scale is exaggerated for readability and z is head elevation in feet. These are measured heads, not a calibrated groundwater model.
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.
How the corridor is assembled
For each reach whose gain/loss has shifted (Trends tab): the wells within 2 miles of its anchoring gage, their pooled water-table history over the same era, and an advisory Glover screen of lagged stream depletion from nearby metered pumping. v1 proximity = distance to the reach's anchoring gage; segment-based reach join is a flagged upgrade.
RIO BLANCO AT THE MOUTH NEAR TRUJILLO: 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.
40% are constructed wells; 0% tie to a decreed structure. A permit is permission to drill, not a water right; most here are exempt household wells. More in three things called “well”, or turn on the Well permits chip on the map above to see where they sit.
Permits issued here, by year
5 located water-supply permits with an issue date, 2024 to 2024; half of them had been issued by 2024, and the busiest year was 2024 with 5. A permit is not a well, and the year is the date the paper was issued, not a drilling date.
water-supply permits issued that year
The counts by year, as a table
| Year | Issued | Monitoring holes | Water-supply | Issued through that year |
|---|---|---|---|---|
| 2024 | 5 | 0 | 5 | 5 |
Every district in the file on one scale · the whole file, one year at a time · Plate 4 of the Driller’s Atlas.
The Driller’s Atlas · Plate 2 A cross-section nobody surveyed
Every permitted well within a few miles of the line, drawn from the ground to its drilled depth as the driller filed it. The bright part of each stroke is the perforated casing — where the well actually takes water — coloured by the aquifer named on the permit. Nobody arranged these; the aquifers arrange themselves.
The ground each well hangs from is a 1-km elevation model sampled at the point the permit was spotted, so the profile is real topography smoothed to about a kilometre — peaks are shaved, valleys filled a little — and the depths are the driller’s, measured down from that ground.
Hover or arrow through the strokes to read a well.
The same corridor as a table
| Miles from A | Wells drawn | Median depth (ft) | With a screen | Most-named aquifer | No depth filed | Ground, ft above sea level (median) |
|---|
Bins run from end A to end B of the line. “Most-named aquifer” is the family most often named on permits in the bin, with its count; permits naming no aquifer are the majority of the file and are not a family.
Reservoirs
Source DWR administrative record · verify at DWR structure records ↗
67 reservoir(s) with 4,542 storage measurement(s), 1970–2025. Basin storage as of 2025-09-01 (the record's own end — reservoir records publish ~annually): 75 AF across 4 reservoir(s).
Why storage matters to the flow network
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?
What “full” is measured against
Bubble size is proportional to a reservoir's record-high storage. Fill is its 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 as a share of its own record high otherwise. A wrong capacity would be worse than an honest record high, so only confident joins upgrade.
A dashed teal ring marks reservoirs reporting live DWR telemetry: their fill reflects yesterday's storage, is drawn as a dotted tail on charts, and is treated as provisional until the next verified HydroBase snapshot supersedes it.
A dashed red ring marks a dam under an active storage restriction from DWR's Dam Safety branch — the State Engineer has limited how much it may legally store, so a low fill can be an order, not a drought. Hazard class and inspection condition come from the same record, joined only where the dam carries this reservoir's WDID or a confident NID match — a wrong dam's restriction would be worse than none shown.
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.
| Reservoir | Last recorded storage (AF) | As of | Full | Dam (DWR Dam Safety) | |
|---|---|---|---|---|---|
| ▸ ECHO CANYON RESERVOIR (2903654) | 2,150 | 2011-10-31 | — | — | dossier → |
| ▸ MOUNTAIN VIEW RESERVOIR (2903848) | 1,010 | 2006-10-31 | — | — | dossier → |
| ▸ MOUNTAIN VIEW RESV (ALT) (2903849) | 925 | 2012-10-31 | — | — | dossier → |
| ▸ BORNS LAKE RESERVOIR (2903644) | 68 | 2015-10-29 | — | — | dossier → |
| ▸ TURKEY CREEK RANCH R #2 (2903782) | 55 | 2024-08-27 | — | — | dossier → |
| ▸ THOMAS RESERVOIR (2903682) | 50 | 2015-10-28 | — | — | dossier → |
| ▸ VILLAGE LAKE (2903696) | 49 | 2012-10-30 | — | — | dossier → |
| ▸ BROWN PUMPSITE (2901020) | 33 | 2023-10-31 | — | — | dossier → |
Snow and runoff
Source Independent agency measurement · fetched 2026-10-16 · verify at NRCS report generator ↗ Source Our computation, scored against a reference · NRCS forecast, graded here against the gage record
Snow-water equivalent, WY2027
| SNOTEL site | Elev (ft) | SWE (in) | Median (in) | % of median | Typical peak |
|---|---|---|---|---|---|
| Upper San Juan | 10140 | 0.0 | 0.0 | — | April 9 (29.7 in) |
| Wolf Creek Summit | 10930 | 1.1 | 0.1 | — | April 29 (35.5 in) |
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 (1979–2026)
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 13 of the last 48 winters the snow never came — the pack peaked below 80% of its median. In 3 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, 1988, 1996, 2000, 2002, 2006, 2012, 2013, 2014, 2015, 2018, 2025, 2026. The snow left early: 2020, 2022, 2024.
Computed by this site from 2 SNOTEL sites’ full daily records (NRCS AWDB, back to 1979). 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 — Rio Blanco at Blanco Diversion
NRCS's final issue (2026-06-01) calls it even odds that at least 4 kAF arrives over 06-01 to 07-31 — 23% of a normal season; almost certainly at least 3, probably not more than 11. Our own record at this gage shows 2 kAF actually delivered. New forecasts begin in January. How to read these numbers →
We test a record-based adjustment of the April benchmark at every graded point. Here it did not beat NRCS over 32 replayed seasons (14% typical miss unadjusted vs 14% adjusted), so none is shown — NRCS’s own forecast, unadjusted, is the best April benchmark available for this river. Why we test →
| 90% chance of at least | 70% chance of at least | 50% chance of at least | 30% chance of at least | 10% chance of at least | Normal | Observed |
|---|---|---|---|---|---|---|
| 3 | 3 | 4 | 7 | 11 | 18 | 2 |
How good are these forecasts here? (1993–2026)
Grading every April issue against what the river then delivered, measured against NRCS’s naturalized volumes (this point forecasts the river as it would run without upstream storage and diversions — which no gage measures) — 33 seasons: the median miss of the 50% forecast is 13%, with a low bias of 0%, and the observed volume landed inside the stated 10–90% band 82% 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 NRCS’s own naturalized monthly volumes; years missing any month 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 (1979–2026)
Across 48 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 75% 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 1.1). In warm, early-melt years the river delivered a median of 73% of a normal season, against 136% 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.
Runoff outlook — San Juan R nr Carracas
NRCS's final issue (2026-06-01) calls it even odds that at least 25 kAF arrives over 06-01 to 07-31 — 19% of a normal season; almost certainly at least 13, probably not more than 62. Our own record at this gage shows 16 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 85 kAF over 04-01 to 07-31. 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 84 kAF. The river delivered 82 kAF.
Computed by this site — not an NRCS number, and shown only because it earned it: replayed over 66 past seasons here (1966–2025), never seeing the year it predicts, the adjustment cut the typical April miss from 31% to 21%. 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 →
| 90% chance of at least | 70% chance of at least | 50% chance of at least | 30% chance of at least | 10% chance of at least | Normal | Observed |
|---|---|---|---|---|---|---|
| 13 | 19 | 25 | 40 | 62 | 131 | 16 |
How good are these forecasts here? (1965–2025)
Grading every April issue against what the river then delivered, measured at this gage’s own record — 60 seasons: the median miss of the 50% forecast is 35%, with a high bias of 34%, and the observed volume landed inside the stated 10–90% band 56% 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 (1979–2026)
Across 48 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 65% 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 1.3). In warm, early-melt years the river delivered a median of 63% of a normal season, against 128% 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.
Drought
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 68th-driest week 39 in 93 years of record at SAN JUAN RIVER AT FARMINGTON, NM (as of 2026-09-21; 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, Mineral County is 57% in D2 severe 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 1930, week by week
Each thin row is a year at SAN JUAN RIVER AT FARMINGTON, NM; 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 2003 (mean gap 12.6 percentile points; next closest 2013 (13.1), 2025 (13.1)). 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 Archuleta, Mineral, San Juan 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 (53 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
| Drought | Span | Weeks | Trough percentile | Flows recovered | Water table back |
|---|---|---|---|---|---|
| unnamed dry spell | 2026-05-04 → 2026-09-21 | 20 | 17th (2026-07-06) | not yet | — |
| unnamed dry spell | 2025-05-05 → 2025-12-08 | 31 | 17th (2025-07-07) | not yet | — |
| unnamed dry spell | 2024-01-08 → 2024-11-11 | 44 | 19th (2024-06-17) | not yet | — |
| the 2020-22 drought | 2020-06-08 → 2023-06-19 | 158 | 19th (2020-08-17) | 14 weeks | — |
| the 2018 drought | 2018-03-26 → 2019-06-17 | 64 | 13th (2018-07-09) | 5 weeks | — |
| the 2012-13 drought | 2014-05-12 → 2014-10-06 | 21 | 26th (2014-06-30) | 9 weeks | — |
| the 2012-13 drought | 2013-03-25 → 2013-11-25 | 35 | 16th (2013-07-22) | 54 weeks | — |
| the 2002 drought | 2003-05-12 → 2004-08-16 | 66 | 19th (2004-03-15) | 25 weeks | — |
| the 2002 drought | 2002-06-03 → 2003-01-20 | 33 | 15th (2002-08-12) | 107 weeks | — |
| unnamed dry spell | 1990-06-25 → 1990-12-03 | 23 | 22nd (1990-08-27) | 2 weeks | — |
| the 1977 drought | 1977-06-27 → 1978-01-23 | 30 | 16th (1977-08-08) | 6 weeks | 3 yr (15 wells, 2 still below) |
| unnamed dry spell | 1967-07-24 → 1968-07-29 | 53 | 17th (1968-03-11) | 31 weeks | — |
| the 1963-64 drought | 1962-12-10 → 1964-10-12 | 96 | 9th (1964-05-11) | 24 weeks | — |
| unnamed dry spell | 1960-11-28 → 1961-07-03 | 31 | 16th (1961-03-06) | 7 weeks | — |
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 (782 rights across 96 years of shared record), colored by that year’s wetness from the barcode above. Here the correlation is +0.14 — 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.
Legal
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 12,104 people served, a figure that counts a wholesaler's customers twice); none carries an open health-based violation on EPA's record.
| System | Serves | Source | Here |
|---|---|---|---|
| PAGOSA AREA WSD | 11,069 | Surface water | 29% of its area |
| SAN JUAN RIVER VILLAGE MD | 877 | Groundwater under the influence of surface water | 100% of its area |
| ALPINE LAKES RANCH WC | 158 | Purchased surface water | 100% of its area |
Instream-flow rights held by the state
Source Register of another agency · fetched 2026-10-11 · verify at CWCB instream flow program ↗
16 reaches over 106.7 miles and 3 natural lake levels, held by the Colorado Water Conservation Board so that water stays in the stream. Every reach, with its schedule and case →
- Rio Blanco, 16.0 mi: 20 (10/1 - 4/30), 29 (5/1 - 9/30) cfs (appropriated 1974, 74W1295) · dossier
- Turkey Creek, 12.5 mi: 4 (1/1 - 12/31) cfs (appropriated 1980, 80CW0039) · dossier
- San Juan River, 11.5 mi: 50 (3/1 - 8/31), 30 (9/1 - 2/29) cfs (appropriated 1980, 80CW0040) · dossier
- West Fork San Juan River, 11.3 mi: 14 (3/1 - 8/31), 8 (9/1 - 2/29) cfs (appropriated 1980, 80CW0030) · dossier
- Wolf Creek, 7.9 mi: 11 (3/1 - 8/31), 6 (9/1 - 2/29) cfs (appropriated 1980, 80CW0031) · dossier
- Quartz Creek, 7.5 mi: 8 (1/1 - 12/31) cfs (appropriated 1980, 80CW0035) · dossier
and 13 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 1868-03-02 to 2025-05-28. Of the 20 structures with a yield estimate, the median one’s senior right was in priority 2% of a median irrigation season and 0% in a dry one. 25 abandonment screens and 194 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: 1092 across 853 structure(s); 285 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.
The three measures, year by year
One row per whole calendar year inside the call record's coverage (23 years); partly-covered years are omitted rather than reported as quiet. Trend is Mann-Kendall with the same significance gate as every other trend on this site. Counted from DWR's published call record, which begins in the early 2000s: earlier years are absent, not quiet. A rise in the number of calls set can also reflect how finely an administrator records one episode, which is why days under call -- insensitive to that -- is the component to read first. Advisory summary of the public record, not an administrative finding.
| Year | Days under call | Calls set | Controlling priority (median) |
|---|---|---|---|
| 2014 | 319 | 117 | 1883-05-15 |
| 2015 | 316 | 90 | 1899-05-13 |
| 2016 | 273 | 94 | 1888-02-08 |
| 2017 | 297 | 98 | 1904-01-02 |
| 2018 | 285 | 164 | 1878-05-15 |
| 2019 | 186 | 53 | 1880-06-01 |
| 2020 | 240 | 171 | 1986-11-23 |
| 2021 | 246 | 143 | 1876-11-01 |
| 2022 | 261 | 161 | 1888-03-20 |
| 2023 | 198 | 82 | 1880-06-01 |
| 2024 | 231 | 114 | 1876-10-10 |
| 2025 | 281 | 169 | 1888-03-20 |
Why diversions stopped — call-based explanations
Sustained diversion stops matched to senior administrative calls.
- BERRYHILL DITCH NO 2 (2900529) DWR↗ stopped 2025-07-30 (93+ days) — call at HENRY BOLEN DITCH curtailing 100% of its decreed rate [heuristic-strong]
- BRUCE SPRUCE DITCH (2900548) DWR↗ stopped 2025-07-27 (96+ days) — call at HENRY BOLEN DITCH curtailing 100% of its decreed rate [heuristic-strong]
- BIRT SMITH DITCH (2900531) DWR↗ stopped 2025-06-24 (129+ days) — call at LA PLATA RIVER BASIN curtailing 100% of its decreed rate [heuristic-strong]
- BROWN DITCH (2900546) DWR↗ stopped 2025-06-24 (85+ days) — call at LA PLATA RIVER BASIN curtailing 100% of its decreed rate [heuristic-strong]
- CATCHPOLE MEADOW DITCH (2900557) DWR↗ stopped 2025-06-23 (130+ days) — call at LA PLATA RIVER BASIN curtailing 100% of its decreed rate [heuristic-strong]
- ALLEN DITCH (2900502) DWR↗ stopped 2025-06-17 (29+ days) — call at HENRY BOLEN DITCH curtailing 100% of its decreed rate [heuristic-strong]
- BIRT SMITH DITCH (2900531) DWR↗ stopped 2025-06-03 (7+ days) — call at CARPENTER AND MITCHELL D curtailing 100% of its decreed rate [heuristic-strong]
- CABE DITCH (2900551) DWR↗ stopped 2024-09-30 (238+ days) — call at SPRING CREEK DITCH curtailing 86% of its decreed rate [heuristic-partial]
- BIRT SMITH DITCH (2900531) DWR↗ stopped 2024-09-22 (218+ days) — call at HENRY BOLEN DITCH curtailing 100% of its decreed rate [heuristic-strong]
- BROWN DITCH (2900546) DWR↗ stopped 2024-09-12 (228+ days) — call at HENRY BOLEN DITCH curtailing 100% of its decreed rate [heuristic-strong]
- BERRYHILL DITCH NO 2 (2900529) DWR↗ stopped 2024-09-10 (274+ days) — call at HENRY BOLEN DITCH curtailing 100% of its decreed rate [heuristic-strong]
- CANON CREEK DITCH (2900553) DWR↗ stopped 2024-09-02 (261+ 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.
| Structure | Senior priority | Senior right: median / dry yr | Junior right: median / dry yr |
|---|---|---|---|
| PARK DITCH (2900686) DWR↗ | 1886-07-01 | 36.0% / 17.3% | 1.4% / 0.0% |
| SAN JUAN RIVER MIN FLOW (2901900) DWR↗ | 1980-01-30 | 2.3% / 0.0% | 2.3% / 0.0% |
| CHAPSON AND HOWE DITCH (2900560) DWR↗ | 1890-10-31 | 23.4% / 0.0% | 2.3% / 0.0% |
| SNOWBALL DITCH (2900718) DWR↗ | 1896-06-27 | 22.8% / 0.0% | 9.8% / 0.0% |
| FOUR-MILE DITCH (2900601) DWR↗ | 1890-10-15 | 23.4% / 0.0% | 2.3% / 0.0% |
| RIO BLANCO MIN FLOW (2900768) DWR↗ | 1974-12-04 | 2.3% / 0.0% | 2.3% / 0.0% |
| MESA DITCH (2900669) DWR↗ | 1891-01-12 | 23.4% / 0.0% | 9.8% / 0.0% |
| ECHO DITCH (2900588) DWR↗ | 1881-05-01 | 51.4% / 22.0% | 2.3% / 0.0% |
| DUTTON COLLECTION DITCH (2902007) DWR↗ | 1912-12-31 | 2.3% / 0.0% | 2.3% / 0.0% |
| EAST FK SAN JUAN R MIN F (2901904) DWR↗ | 1980-01-30 | 2.3% / 0.0% | 2.3% / 0.0% |
| WEST FK SAN JUAN R MIN F (2901902) DWR↗ | 1980-01-30 | 2.3% / 0.0% | 2.3% / 0.0% |
| DUTTON DITCH (2902005) DWR↗ | 1909-06-03 | 2.3% / 0.0% | 2.3% / 0.0% |
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 ~1974 — idleness that begins before then may be unreported use, not nonuse (flagged † below).
- DRY GULCH DITCH - USFS (2900586) DWR↗ (1944-10-06, 1.5 cfs decreed): last active 1965 — 60 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1974) -- early absence of record is weak evidence of nonuse
- POND DITCH (2900693) DWR↗ (1911-12-31, 0.0 cfs decreed): last active 1965 — 60 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1974) -- early absence of record is weak evidence of nonuse
- TOWN OF PAGOSA SPRINGS PIPELINE & RESERV (2903695) DWR↗ (1902-05-15, 3.0 cfs decreed): last active 1965 — 60 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1974) -- early absence of record is weak evidence of nonuse
- TEAL LAKE DITCH (2900735) DWR↗ (1959-06-02, 0.5 cfs decreed): last active 1967 — 58 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1974) -- early absence of record is weak evidence of nonuse
- AT LAST SPRING NO 2 (2900511) DWR↗ (1910-06-01, 0.0 cfs decreed): last active 1974 — 51 years idle
- BROWN-BENNETT P L (2900545) DWR↗ (1968-06-30, 1.0 cfs decreed): last active 1974 — 51 years idle
- BROWN SPRING & PIPELINE (2900547) DWR↗ (1951-10-01, 0.1 cfs decreed): last active 1974 — 51 years idle
- STINKING SPRING D NO 1 (2900726) DWR↗ (1962-06-01, 2.0 cfs decreed): last active 1974 — 51 years idle
- STINKING SPRINGS D NO 2 (2900727) DWR↗ (1962-06-01, 1.0 cfs decreed): last active 1974 — 51 years idle
- BLAYLOCK PUMP & PIPELINE (2905002) DWR↗ (1969-08-01, 0.0 cfs decreed): last active 1974 — 51 years idle
Compliance screens (194 advisory flags)
Screened 253 of 853 structures with rights (297 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.
- C H LOUCKS DITCH (2900550) DWR↗: Observed p99 daily rate 130.0 cfs (max 130.0) exceeds total decreed absolute 6.8 cfs across 16783 recorded day(s).
- WHITE CREEK NO 1 DITCH (2900753) DWR↗: Observed p99 daily rate 70.0 cfs (max 70.0) exceeds total decreed absolute 5.0 cfs across 12843 recorded day(s).
- PARK DITCH (2900686) DWR↗: Observed p99 daily rate 60.2 cfs (max 82.2) exceeds total decreed absolute 60.0 cfs across 23257 recorded day(s).
- COLTON AND MONTROY DITCH (2900566) DWR↗: Observed p99 daily rate 15.4 cfs (max 27.4) exceeds total decreed absolute 4.5 cfs across 19697 recorded day(s).
- LONG HORN AND MEE DITCH (2900653) DWR↗: Observed p99 daily rate 14.4 cfs (max 15.0) exceeds total decreed absolute 14.2 cfs across 8702 recorded day(s).
- MURPHY DITCH (2900672) DWR↗: Observed p99 daily rate 12.2 cfs (max 12.7) exceeds total decreed absolute 3.0 cfs across 4522 recorded day(s).
- CARR DITCH (2900555) DWR↗: Observed p99 daily rate 12.0 cfs (max 13.0) exceeds total decreed absolute 8.6 cfs across 14912 recorded day(s).
- KELLY'S LAKE DITCH (2901028) DWR↗: Observed p99 daily rate 11.6 cfs (max 11.6) exceeds total decreed absolute 10.0 cfs across 3868 recorded day(s).
- SAN JUAN DITCH (2900706) DWR↗: Observed p99 daily rate 10.4 cfs (max 12.2) exceeds total decreed absolute 1.6 cfs across 1570 recorded day(s).
- SISSON-STEPHENS DITCH (2900716) DWR↗: Observed p99 daily rate 10.3 cfs (max 13.9) exceeds total decreed absolute 10.0 cfs across 10439 recorded day(s).
Seniority (top structures by decreed rate)
| Structure | Senior priority date | Rights | Decreed abs (cfs) | Decreed abs (AF) | Conditional? |
|---|---|---|---|---|---|
| PARK DITCH (2900686) DWR↗ | 1886-07-01 | 8 | 60.0 | 0 | yes |
| SAN JUAN RIVER MIN FLOW (2901900) DWR↗ | 1980-01-30 | 1 | 50.0 | 0 | — |
| CHAPSON AND HOWE DITCH (2900560) DWR↗ | 1890-10-31 | 5 | 45.6 | 0 | — |
| SNOWBALL DITCH (2900718) DWR↗ | 1896-06-27 | 4 | 38.5 | 0 | — |
| FOUR-MILE DITCH (2900601) DWR↗ | 1890-10-15 | 5 | 34.0 | 0 | — |
| RIO BLANCO MIN FLOW (2900768) DWR↗ | 1974-12-04 | 1 | 29.0 | 0 | — |
| MESA DITCH (2900669) DWR↗ | 1891-01-12 | 5 | 28.5 | 0 | — |
| ECHO DITCH (2900588) DWR↗ | 1881-05-01 | 7 | 27.8 | 0 | — |
| DUTTON COLLECTION DITCH (2902007) DWR↗ | 1912-12-31 | 2 | 25.5 | 0 | — |
| WEST FK SAN JUAN R MIN F (2901902) DWR↗ | 1980-01-30 | 1 | 25.0 | 0 | — |
| EAST FK SAN JUAN R MIN F (2901904) DWR↗ | 1980-01-30 | 1 | 25.0 | 0 | — |
| DUTTON DITCH (2902005) DWR↗ | 1909-06-03 | 2 | 22.9 | 0 | — |
| EAST FK SAN JUAN R MIN F (2901903) DWR↗ | 1980-01-30 | 1 | 15.0 | 0 | — |
| LONG HORN AND MEE DITCH (2900653) DWR↗ | 1899-12-31 | 3 | 14.2 | 0 | — |
| FISH CREEK DITCH (2900597) DWR↗ | 1897-06-01 | 4 | 14.0 | 0 | — |
Recent inventory & legal-document changes
- 2026-10-01 — call released: 39556
- 2026-10-01 — call released: 37181
- 2026-09-30 — call released: 39596
- 2026-09-29 — call set: LA PLATA RIVER BASIN (39596)
- 2026-09-29 — call released: 38755
- 2026-09-26 — call released: 39564
- 2026-09-25 — call set: COTTONWOOD DITCH NO 2 (39564)
- 2026-09-25 — call released: 39537
Water-court filings this month (division-wide)
14 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 (15 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.
All 14 filings, with excerpts
| Case | What it asks | County | Excerpt |
|---|---|---|---|
09CW4
|
plan for augmentation | — | Case No. 09CW4. Applicant has installed parshall flumes, including one below the Lower Pond, and other measuring devices to administer the water rights that are the subject of this application and the related plan for augmentation. 4. Detailed outline of work … |
18CW3041
|
reasonable diligence | — | Case No. 18CW3041, for which Co-Applicants request entry of a finding of reasonable diligence: A. Dry Gulch Reservoir. i. Location: off-channel reservoir located on Dry Gulch, an ephemeral tributary to the San Juan River. The center point on the dam axis is lo… |
2026CW3018
|
— | LA PLATA | 2026CW3018 La Plata County, Water District No. 7 1. Name, address, and telephone number of applicant: South Durango Sanitation District, PO Box 2420, Durango, CO 81302, 970 -382-2623; Attorney: Floyd L. Smith, 48 CR 250, Suite 5, Durango, CO 81301; 2. Name of … |
2026CW3019
|
— | LA PLATA | 2026CW3019 La Plata County, Water District No. 7 1. Name, address, and telephone number of applicant: South Durango Sanitation District, PO Box 2420, Durango, CO 81302, 970-382- 2623; Attorney: Floyd L. Smith, 48 CR 250, Suite 5, Durango, CO 81301; 2. Name of … |
2026CW3020
|
new underground right | LA PLATA | 2026CW3020 La Plata County, 4M Ventures LLC (“Applicant”), c/o Trisha Mead, Managing Member, 213 Hottell Lane, Bayfield, Colorado 81122, Telephone: (970) 259-4346. APPLICATION FOR UNDERGROUND WATER RIGHT in LA PLATA COUNTY. Please send all pleadings and corres… |
2026CW3021
|
reasonable diligence | ARCHULETA | 2026CW3021 Archuleta County, (19CW3032) APPLICATION FOR FINDING OF REASONABLE DILIGENCE IN ARCHULETA COUNTY, COLORADO 1. Name and address of Applicant: Her Majesty’s Ranch, LLC Attention: Grant Gottfurcht, Member P.O. Box 3729 Pagosa Springs, CO 81147 (970) 73… |
2026CW3022
|
reasonable diligence | ARCHULETA | 2026CW3022 Archuleta County, Application for Finding of Reasonable Diligence. 1. Applicants: Pagosa Area Water and Sanitation District (“PAWSD”), P. O. Box 4610, Pagosa Springs, CO 81157, (970) 731-2691, and San Juan Water Conservancy District (“SJWCD”), P.O. … |
2026CW3023
|
— | MINERAL | 2026CW3023 Mineral County, (17CW3043, 10CW71, 98CW88)… |
2026CW3024
|
— | MINERAL | 2026CW3024 Mineral County, (17CW3050)… |
2026CW3025
|
reasonable diligence | MINERAL | 2026CW3025 (ref. 17CW3030, 73 -308D, et al.), MINERAL COUNTY AND ARCHULETA COUNTY, APPLICATION FOR FINDING OF REASONABLE DILIGENCE. Pagosa Area Water and Sanitation District (“PAWSD”), 100 Lyn Ave, Pagosa Springs, CO 81147, (970) 731 -2691; and San Juan Water … |
2026CW3026
|
reasonable diligence, make absolute | ARCHULETA | 2026CW3026 (ref. 17CW3014, 83CW145, et al.); ARCHULETA COUNTY; APPLICATION FOR FINDING OF REASONABLE DILIGENCE AND TO MAKE ABSOLUTE IN PART; Name, address, and telephone number of Applicant: Pagosa Area Water and Sanitation District (“District”) 100 Lyn Ave Pa… |
2026CW5
|
— | LA PLATA | 2026CW5 La Plata County, Matilda Reed and Jimmy Reed, 718 E 8 th Ave, Durango, CO 81301: Alolo Springs (Pipeline); Located in the NE 1/4 SE 1/4 of Section 29, T35N, R9W, NMPM, UTM coordinates: Easting 245440, Northing 4128618; An unnamed tributary of the Anima… |
2026CW6
|
— | SAN JUAN | 2026CW6 San Juan County, Seth Weber and Chelsea Weber, PO Box 461 Paonia, CO 81428: Wild Bunch (Pipeline); Date of Original Decree: 11/30/2007 Case No. 06CW127, Subsequent decrees: Date of Decree: 3/10/2016 Case No. 13CW3034, Date of Decree: 10/6/2022 Case No.… |
2026CW7
|
— | MONTEZUMA | 2026CW7 Montezuma County, Paul J. Bohmann and Mary M. Vozar, 5892 Road 38 Mancos, CO 81328 : Wilburm Tailwater Culvert (tailwater culvert); SE 1/4, NW1/4, Section 14, T35N, R14W, N.M.P.M., UTM Coordinates: Easting 37.297915, Northing -108.364547, Tailwater via… |
Water quality
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 2026-10-16 · 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.
| Site | Temp °C | Cond µS/cm | DO mg/L | Turb FNU | As of |
|---|---|---|---|---|---|
| SAN JUAN RIVER NEAR CO RD 119 AT PAGOSA SPRINGS CO ↗ | 5.7 | 97 | 2026-10-16 11:30 |
Where water has been sampled
Source Register of another agency · fetched 2026-10-08 · verify at Water Quality Portal ↗
The portal lists 670 sampling stations in this district's watershed (Upper San Juan 14080101), of which 78 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: Southern Ute Tribe (37), Colorado Dept. of Public Health & Environment-WQCD (16), Mountain Studies Institute (MSI) (14). Most-sampled groups: Inorganics, Major, Metals, Physical, Nutrient, Organics, Other. 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 1 of them for PFAS in 2023–25; none had PFOA or PFOS at or above the 2024 limit.
| System | Serves | EPA record | PFAS (UCMR 5) | Lead, latest 90th pct |
|---|---|---|---|---|
| PAGOSA AREA WSD | 11,069 | clean, last 12 quarters | none detected | 0.0024 mg/L |
| SAN JUAN RIVER VILLAGE MD | 877 | clean, last 12 quarters | not sampled | 0.003 mg/L |
| ALPINE LAKES RANCH WC | 158 | clean, last 12 quarters | not sampled | 0.0012 mg/L |
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.
Call cascade
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.
What this does and doesn't model. Seniority arithmetic only: every right junior to the call is treated as curtailed. It does not model reach applicability — structures downstream of the calling point are not administered by it — and it applies no futile-call judgment. Read it as “who is junior to this date, and by how much,” not as a prediction of what the Division Engineer would actually order.
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
DWR administration numbers encode appropriation and adjudication dates; lower is more senior.
This week's diagnostic
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System status
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Active river calls
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Hydrographs vs. historical envelope
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Anomaly flags
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Snowpack — 2 SNOTEL sites report here. Runoff outlook — Rio Blanco at Blanco Diversion : even odds of at least 4 kAF over 06-01 to 07-31 — 23% of a normal season, per NRCS, issued 2026-06-01 — the season’s final; new forecasts begin in January. Runoff outlook — San Juan R nr Carracas : even odds of at least 25 kAF over 06-01 to 07-31 — 19% of a normal season, per NRCS, issued 2026-06-01 — the season’s final; new forecasts begin in January. Full snow & runoff picture — charts, forecast history and how the forecasts have verified →
Sites, exceedance bands and sources
| SNOTEL site | Elev (ft) | SWE (in) | Median (in) | % of median | Typical peak |
|---|---|---|---|---|---|
| Upper San Juan | 10140 | 0.0 | 0.0 | — | April 9 (29.7 in) |
| Wolf Creek Summit | 10930 | 1.1 | 0.1 | — | April 29 (35.5 in) |
Rio Blanco at Blanco Diversion — 06-01 to 07-31 volume, thousand acre-feet (chance the volume is AT LEAST this):
| 90% | 70% | 50% | 30% | 10% | Normal |
|---|---|---|---|---|---|
| 3 | 3 | 4 | 7 | 11 | 18 |
San Juan R nr Carracas — 06-01 to 07-31 volume, thousand acre-feet (chance the volume is AT LEAST this):
| 90% | 70% | 50% | 30% | 10% | Normal |
|---|---|---|---|---|---|
| 13 | 19 | 25 | 40 | 62 | 131 |
Snow-water equivalent and medians (1991–2020) from NRCS SNOTEL; seasonal volume forecasts from the NRCS National Water and Climate Center. Sites and forecast points are assigned to the district whose boundary contains them — snowpack that feeds this district can also sit in a neighboring headwater district. Toggle the Snow chip on the map above to see the sites.
Topology cross-check: 3 parent disagreements, 5 sizable streams not on this network (vs DWR's route framework — under review)
This flow network was built mechanically; DWR's Source Water Route Framework disagrees with it in the places below. Each row is a question a human reviewer has not yet answered — not an error verdict. Checked 15 streams, 12 agree. Know this water? Tell us →
| Stream | This site routes it to | DWR routes it to |
|---|---|---|
| Rito Blanco | the mainstem | Rio Blanco |
| Sawmill Creek | the mainstem | Rito Blanco |
| Sheep Cabin Creek | the mainstem | Rito Blanco |
Sizable streams DWR maps here that this network does not carry:
Squaw Canyon (6 mi) · Arroyo Escondido (5 mi) · Horse Gulch (5 mi) · Trail Canyon (4 mi) · Johnny Creek (3 mi)