San Juan River Basin

Division 7 · Water District 29

Auto-mapped

San Juan River Basin on the ground — the ditches, wells, reservoirs and gages of Water District 29 · clicktap anything for its record

Snowpack — no snow on the ground at 2 SNOTEL sites — normal for the date; the snow year begins in October and typically peaks around April 9. 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	0.1	0.0	—	April 9 (29.7 in)
Wolf Creek Summit	10930	0.0	0.0	—	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)

Full diagnostic snapshot pending — this district's weekly-style report (system status, active calls, hydrographs, anomaly flags) is produced by the nightly rotation and appears here after its first run. The tabs above are live now.

Reconstruct conditions as of

Evolution of the network

This year, in context

In the weeks around 2026-07-06 (the newest reading on file), flows at the 7 ranked gages are running at a median 27% of their own long-term norm for this window — 6 below a typical year, 1 at or above. Driest relative to its record: BLANCO DIVERSION NEAR PAGOSA SPRINGS, ranking 1st lowest of 36 years.

How this comparison is made

Each gage's mean flow over the 3 days either side of 2026-07-06, 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 2026-08-30 21:12 from 19 gage(s) with cached period-of-record data. The series is each gage's annual mean flow in cfs (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 56-year window with full coverage (1971–2026), the dominant shared pattern across 3 gage(s) explains 79% of year-to-year variance (almost certainly a basin-wide climate/snowpack driver).

All gages in this window move with the shared pattern -- no localized outlier.

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

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

R-1812 (diversion): +135.6 cfs (17% of that reach's correction)
R-1811 (diversion): +135.6 cfs (17% of that reach's correction)
VELASQUEZ DITCH (diversion): +135.6 cfs (17% of that reach's correction)
ROSA DITCH (diversion): +135.6 cfs (17% of that reach's correction)
DARLINGTON WASTE WATER D (diversion): +135.6 cfs (17% of that reach's correction)
PENINSULA DITCH NO 2 (diversion): +135.6 cfs (17% of that reach's correction)
PSRC #9 (diversion): +0.1 cfs (1% of that reach's correction)
COUNTY OUTFLOW #1 (diversion): +0.1 cfs (1% of that reach's correction)
PSRC #8 (diversion): +0.1 cfs (1% of that reach's correction)
PSRC SPRING 2000-1 (return): +0.1 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_20260707 (imported 2026-08-19) for history, plus the CDSS REST API for current conditions.

Check	State	What was measured
gage freshness	stale	newest gage reading is 55 day(s) old (target 7)
diversion record	expected-lag	newest diversion record is 304 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) / 254,398 daily values (1930-10-01–2026-07-06); 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.

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.

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-water equivalent, WY2026

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

SNOTEL site	Elev (ft)	SWE (in)	Median (in)	% of median	Typical peak
Upper San Juan	10140	0.1	0.0	—	April 9 (29.7 in)
Wolf Creek Summit	10930	0.0	0.0	—	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 drought), 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. This year was one of the dry ones: the pack peaked at 43% of median.

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 1 kAF actually delivered (partial record: 36 of 61 days). New forecasts begin in January. How to read these numbers →

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	1

How good are these forecasts here? (1993–2025)

Grading every April issue against what the river then delivered, measured at this gage’s own record — 32 seasons: the median miss of the 50% forecast is 415%, with a high bias of 415%, and the observed volume landed inside the stated 10–90% band 0% 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 (1979–2025)

Across 47 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 97% of a normal season (a snow-to-runoff elasticity of 1.2). In warm, early-melt years the river delivered a median of 90% of a normal season, against 221% 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 13 kAF actually delivered (partial record: 36 of 61 days). New forecasts begin in January. How to read these numbers →

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	13

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%).

What April snow has meant for this river (1979–2025)

Across 47 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 63% of a normal season (a snow-to-runoff elasticity of 1.4). In warm, early-melt years the river delivered a median of 63% of a normal season, against 127% in typical years — the timing of the melt matters, not just its size.

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 3% 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: 1093 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 call, calls set, seniority 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	41.4% / 17.3%	1.8% / 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	23.6% / 2.8%	2.3% / 0.0%
SNOWBALL DITCH (2900718) DWR↗	1896-06-27	23.3% / 1.4%	11.7% / 0.0%
FOUR-MILE DITCH (2900601) DWR↗	1890-10-15	23.6% / 2.8%	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	23.6% / 2.8%	11.7% / 0.0%
ECHO DITCH (2900588) DWR↗	1881-05-01	54.0% / 22.0%	2.3% / 0.0%
DUTTON COLLECTION DITCH (2902007) DWR↗	1912-12-31	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%
EAST FK SAN JUAN R MIN F (2901904) DWR↗	1980-01-30	2.3% / 0.0%	2.3% / 0.0%
DUTTON DITCH (2902005) DWR↗	1909-06-03	4.4% / 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)	Conditional?
PARK DITCH (2900686) DWR↗	1886-07-01	8	60.0	yes
SAN JUAN RIVER MIN FLOW (2901900) DWR↗	1980-01-30	1	50.0	—
CHAPSON AND HOWE DITCH (2900560) DWR↗	1890-10-31	5	45.6	—
SNOWBALL DITCH (2900718) DWR↗	1896-06-27	4	38.5	—
FOUR-MILE DITCH (2900601) DWR↗	1890-10-15	5	34.0	—
RIO BLANCO MIN FLOW (2900768) DWR↗	1974-12-04	1	29.0	—
MESA DITCH (2900669) DWR↗	1891-01-12	5	28.5	—
ECHO DITCH (2900588) DWR↗	1881-05-01	7	27.8	—
DUTTON COLLECTION DITCH (2902007) DWR↗	1912-12-31	2	25.5	—
WEST FK SAN JUAN R MIN F (2901902) DWR↗	1980-01-30	1	25.0	—
EAST FK SAN JUAN R MIN F (2901904) DWR↗	1980-01-30	1	25.0	—
DUTTON DITCH (2902005) DWR↗	1909-06-03	2	22.9	—
EAST FK SAN JUAN R MIN F (2901903) DWR↗	1980-01-30	1	15.0	—
LONG HORN AND MEE DITCH (2900653) DWR↗	1899-12-31	3	14.2	—
FISH CREEK DITCH (2900597) DWR↗	1897-06-01	4	14.0	—

No inventory or legal-document changes detected since the daily watch began.

Water-court filings this month (division-wide)

4 applications in the 2026-07 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 2026-09-30 (30 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 4 filings, with excerpts

Case	What it asks	County	Excerpt
`2026CW3007` 3001335	change of water right	LA PLATA	2026CW3007 La Plata County, AMENDED APPLICATION FOR CHANGE OF WATER RIGHT AND NEW WATER RIGHTS. 1. Name and address of Applicants : Gilleland Enterprises, LLC and C&J Gravel Products, Inc. (“Applicants”)c/o John Gilleland 27661 Highway 160 Durango, CO 81301 jo…
`2026CW3016`	reasonable diligence	LA PLATA	2026CW3016 La Plata County, Application for Finding of Reasonable Diligence in the Florida River Watershed; Prior case no. 18CW3047: Applicant: The Bingel-Davis Gratitude Trust, u/a dated April 17, 2025, c/o Kimberly C. Perdue, Southwest Water and Property Law…
`2026CW3017`	—	LA PLATA	2026CW3017 La Plata County, (20CW3008, 13CW3027, 05CW90)…
`2026CW4`	—	ARCHULETA	2026CW4 Archuleta County, Jess E. Ketchum, 320 Stevens Lake Road, Pagosa Springs, CO 81147: Watson Reservoir (Reservoir Pump); Located in the SW 1/4 SE 1/4 of Section 5, T35N, R2W, NMPM, the axis intersects the East abutment at a point approximately 875 ft. No…

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

Administration number

DWR administration numbers encode appropriation and adjudication dates; lower is more senior.

San Juan River Basin

Schematic

Historical

Evolution of the network

Trends

This year, in context

Gage flow trend & changepoints

How the measurement network itself changed

Mass-balance (network closure) trend

Reach gain/loss shifts (1950–2026)

Cross-gage pattern fingerprint

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

Data provenance & quality

Groundwater

Well map

3D aquifer x-ray

Water-table trends

Stream corridors — the surface connection

Reservoirs

Reservoir map — how full is each vessel?

Basin storage, end of each water year

Largest reservoirs on record

Snow and runoff

Snow-water equivalent, WY2026

Two ways a snow year goes wrong (1979–2026)

Runoff outlook — Rio Blanco at Blanco Diversion

How good are these forecasts here? (1993–2025)

What April snow has meant for this river (1979–2025)

Runoff outlook — San Juan R nr Carracas

How good are these forecasts here? (1965–2025)

What April snow has meant for this river (1979–2025)

Legal

Is the river getting harder to divert from?

Why diversions stopped — call-based explanations

Right yield — how often could these rights actually divert?

Abandonment radar (25 screens)

Compliance screens (194 advisory flags)

Seniority (top structures by decreed rate)

Water-court filings this month (division-wide)

Call cascade

Pick a calling right