Rio Grande

Evolution of the network

This year, in context

In the weeks around 2026-07-06 (the newest reading on file), flows at the 67 ranked gages are running at a median 28% of their own long-term norm for this window — 51 below a typical year, 16 at or above. Driest relative to its record: BASSI NORTH FARM ROAD GRAVEL PIT, ranking 1st lowest of 2 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 19:46 from 97 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 97 gages with enough record, 10 are trending down and 0 up, and 14 carry a detected shift. The clearest is Closed Basin Project Canal near Alamosa, its annual mean flow changing -6.03 cfs per decade (-27.9% of its median annual flow) over 37 years (p<0.0001). The other 79 show no clear signal either way. 4 transbasin gages meter imported or exported water — marked ⇆ below and kept out of these counts, because that flow is an operator's decision, not the basin's hydrology (all transbasin diversions).

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

Gage	Trend	Change / decade cfs · % of median annual flow	Significance	Years	Changepoint
▸ Closed Basin Project Canal near Alamosa☆ CBPALACO	↓ decreasing	-6.03 cfs -27.9%	p<0.001	37	~2009
▸ ⚠️ ⇆ William's Creek-Squaw Pass Ditch at Grizzly Pass☆ WCSDITCO	↑ increasing	+0.08 cfs	p<0.001	54	~1983
▸ Rio Grande near Lobatos☆ RIOLOBCO	↓ decreasing	-34.74 cfs -8.6%	p<0.001	126	~1949
▸ Rio Grande at Embudo, Nm.☆ RIOEMBNM	↓ decreasing	-36.56 cfs -4.8%	p<0.001	127	~1949
▸ ⚠️ San Marcial Conveyance Channel on Rio Grande, Nm☆ SMCRIONM	↓ decreasing	-40.31 cfs -15.9%	p<0.001	71	~1975
▸ Rio Grande below Elephant Butte Dam, Nm☆ RIOELENM	↓ decreasing	-39.58 cfs -4.3%	p<0.001	109	~1949
▸ Rio Grande at Wason, below Creede☆ RIOWASCO	↓ decreasing	-58.17 cfs -9.2%	p=0.007	46	~1929
▸ Rio Grande at Otowi Bridge near San Ildefonso, Nm.☆ RIOOTANM	↓ decreasing	-39.58 cfs -3.3%	p=0.009	122	~1945
▸ Rio Grande at Thirty Mile Bridge near Creede☆ RIOMILCO	↓ decreasing	-5.13 cfs -2.6%	p=0.010	111	~1949
▸ Rio Grande near Del Norte☆ RIODELCO	↓ decreasing	-18.67 cfs -2.1%	p=0.016	127	~1929
▸ ⚠️ ⇆ Weminuche Pass Ditch at Weminuche Pass☆ WEMDITCO	↓ decreasing	-0.26 cfs -18.5%	p=0.024	56	~1986
▸ Rio Grande at Albuquerque, Nm.☆ RIOALBNM	↓ decreasing	-90.81 cfs -9.7%	p=0.026	60	~1999
▸ ⚠️ ⇆ Treasure Pass Ditch at Wolf Creek Pass☆ TREDITCO	no clear trend	-0.02 cfs	p=0.189	56	~1986
▸ ⚠️ Rio Grande Floodway at San Acacia, Nm☆ RGFSANNM	no clear trend	+59.05 cfs +10.0%	p=0.199	67	~1978
▸ ⚠️ Rio Grande Floodway at San Marcial, Nm☆ SMFRIONM	no clear trend	+29.86 cfs +7.3%	p=0.295	76	~1974
▸ ⚠️ ⇆ Don La Font Ditch No. 1 at Piedra Pass☆ DLFDT1CO	no clear trend	-0.00 cfs	p=0.305	46	~1992
▸ Rio Chama below El Vado Dam, Nm☆ RCHELVNM	no clear trend	+6.19 cfs +1.6%	p=0.393	90	~1978
▸ Rio Grande at Alamosa☆ RIOALACO	no clear trend	-4.73 cfs -2.7%	p=0.423	113	~1929

⚠️ 7 gages flagged: their records may have quietly shifted against their neighbours, so treat their trends with caution.

How drift is detected

Every gage's annual flows are compared against each neighbour's as a double-mass curve (Searcy & Hardison, USGS WSP 1541-B); a Pettitt step test looks for a break in the ratio. A gage is flagged only when the breaks AGREE across its references, and a break against an already-suspect gage is never counted against a healthy one. A double-mass break means the ratio between two gages changed, not that either gage is faulty: a new diversion, a reservoir, or an import changes that ratio exactly as a rating shift does. Screening aid for expert review, never a measurement verdict.

79 other gage(s) show no significant trend or changepoint (not shown).

2 of those show a significant trend once extended backwards from a retired neighbour's record: Rio Grande below Taos Junction Bridge near Taos, Nm (126 yr, decreasing); Rio Grande at Wagon Wheel Gap (117 yr, decreasing, suspect). Those are reconstructions, not measurements — each gage's page shows both.

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. 70 gage(s) and 311 structure(s) report in 2026, but structure reporting only reached half its modern level around ~1957. 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)
1880s	1	0
1890s	2	0
1900s	3	0
1910s	9	0
1920s	11	0
1930s	14	0
1940s	18	0
1950s	28	140
1960s	32	184
1970s	36	194
1980s	34	208
1990s	37	272
2000s	45	262
2010s	51	286
2020s	48	273

Mass-balance (network closure) trend

Structure divrec-history backfill coverage as of the last check: 9% of 2957 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 (4600 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 GRANDE AT MONTE VISTA: reach shifted from -934 cfs to +377 cfs summer mean (more gaining, p=0.000, 77 yr) [sedimentary uplands: moderate groundwater connectivity -- gain/loss shifts can be real aquifer response; corroborate with nearby well records] [measurement-evolution caution: this shift co-moves with the growth of the gage/metering network (rho=0.64) -- part of it may be unaccounted water becoming accounted, not hydrologic change] [3 alluvial wells within 2 mi of the gage; pooled water table -1.4 ft (1946–1975, no_trend)]
• PRAIRIE DITCH NEAR SEVEN-MILE PLAZA: reach shifted from -239 cfs to -91 cfs summer mean (more gaining, p=0.004, 17 yr) [sedimentary uplands: moderate groundwater connectivity -- gain/loss shifts can be real aquifer response; corroborate with nearby well records] [4 alluvial wells within 2 mi of the gage; pooled water table -5.6 ft (1947–2005, no_trend)]
• RIO GRANDE AT ALAMOSA: reach shifted from -291 cfs to +194 cfs summer mean (more gaining, p=0.002, 77 yr) [sedimentary uplands: moderate groundwater connectivity -- gain/loss shifts can be real aquifer response; corroborate with nearby well records] [measurement-evolution caution: this shift co-moves with the growth of the gage/metering network (rho=0.62) -- part of it may be unaccounted water becoming accounted, not hydrologic change] [2 alluvial wells within 2 mi of the gage; pooled water table +1.2 ft (1949–2021, increasing)]
• PINOS CREEK NEAR DEL NORTE, CO.: reach shifted from -369 cfs to +30 cfs summer mean (more gaining, p=0.000, 77 yr) [mountain crystalline canyon: minimal groundwater storage -- large or shifting unaccounted losses here are more consistent with data/measurement issues or unmodeled plumbing than with aquifer exchange] [measurement-evolution caution: this shift co-moves with the growth of the gage/metering network (rho=0.63) -- part of it may be unaccounted water becoming accounted, not hydrologic change]
• RIO GRANDE ABOVE TRINCHERA CREEK NEAR LA SAUSES: reach shifted from +43 cfs to +206 cfs summer mean (more gaining, p=0.003, 77 yr) [sedimentary uplands: moderate groundwater connectivity -- gain/loss shifts can be real aquifer response; corroborate with nearby well records] [measurement-evolution caution: this shift co-moves with the growth of the gage/metering network (rho=0.66) -- part of it may be unaccounted water becoming accounted, not hydrologic change]
• BEAVER CREEK BELOW BEAVER CREEK RESERVOIR: reach shifted from -70 cfs to -40 cfs summer mean (more gaining, p=0.009, 29 yr) [sedimentary uplands: moderate groundwater connectivity -- gain/loss shifts can be real aquifer response; corroborate with nearby well records]

Groundwater now has its own tab: 605 monitored well(s), water-table trends, stream corridors, and the advisory depletion screen.

Reservoirs now has its own tab: 66 reservoir(s), end-of-year storage back to 1975, click-to-chart histories.

Cross-gage pattern fingerprint

Over the 115-year window with full coverage (1912–2026), the dominant shared pattern across 3 gage(s) explains 94% 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.

• SONDLES D (diversion): -19.1 cfs (25% of that reach's correction)
• HEILMAN SLOUGH D (diversion): -19.1 cfs (25% of that reach's correction)
• BLANCA CNL (diversion): -19.1 cfs (25% of that reach's correction)
• KENILWORTH CNL (diversion): -19.1 cfs (25% of that reach's correction)
• ORR WASTE D (diversion): +12.6 cfs (6% of that reach's correction)
• EHROWITZ D (diversion): +12.6 cfs (6% of that reach's correction)
• WILLOW ROAD SPRING (return): +12.6 cfs (6% of that reach's correction)
• WILLOW SPRING (return): +12.6 cfs (6% of that reach's correction)
• UPPER HORSE CANYON SPR (return): +12.6 cfs (6% of that reach's correction)
• LOG CANYON SPRING (return): +12.6 cfs (6% of that reach's correction)

52,552 water-level measurements across 605 monitored well(s) — 350 alluvial, 117 bedrock — plus 2 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.

Load 3D x-ray

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 149 well(s) with enough record for a trend test: 95 declining, 7 rising.

Fastest-declining wells	Setting	ft / decade	Span	p
▸ NA04000732CCC☆	alluvial	-10.46	14 yr	0.0228
▸ NA04100636DDD RG33B☆	alluvial	-10.45	25 yr	0.0
▸ NA04000801AAD1 RG29A☆	alluvial	-10.37	10 yr	0.0006
▸ NA04000931BAB1☆	unknown	-8.34	34 yr	0.0001
▸ NA04101032ABB1 EW-40U☆	alluvial	-8.2	33 yr	0.0012
▸ NA04101032ABB2 EW-40C☆	alluvial	-7.96	33 yr	0.0007
▸ NA04100936DDA RG28A☆	alluvial	-7.53	42 yr	0.0
▸ NA04000804BCC2☆	alluvial	-7.17	56 yr	0.0

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 GRANDE AT MONTE VISTA: 3 alluvial well(s) nearby; pooled water table -1.4 ft (1946–1975, no_trend, p=0.2643). Glover screen: 0.4 cfs of nearby metered alluvial pumping → est. lagged depletion 0.2–0.3 cfs (uncalibrated T/S ranges; flagged for SPDSS calibration, AWAS cross-check, and expert review — DWR's AWAS is the authority).

PRAIRIE DITCH NEAR SEVEN-MILE PLAZA: 4 alluvial well(s) nearby; pooled water table -5.6 ft (1947–2005, no_trend, p=0.0892)

RIO GRANDE AT ALAMOSA: 2 alluvial well(s) nearby; pooled water table +1.2 ft (1949–2021, increasing, p=0.0)

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.

66 reservoir(s) with 27,950 storage measurement(s), 1975–2026. Basin storage as of 2025-10-31 (the record's own end — reservoir records publish ~annually): 48,114 AF across 16 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)
▸ RIO GRANDE RES (2003554) ☆	23,219	2025-10-31	—	—	dossier →
▸ CONTINENTAL RES (2003536) ☆	12,320	2025-10-31	—	—	dossier →
▸ SANTA MARIA RES (2003558) ☆	5,176	2025-10-31	—	—	dossier →
▸ BEAVER PARK RES (2003532) ☆	2,714	2025-10-31	—	—	dossier →
▸ BIG MEADOWS RES (2003589) ☆	2,269	2025-10-31	—	—	dossier →
▸ ROAD CANYON RES (2003555) ☆	1,281	2010-10-31	—	—	dossier →
▸ LOST LAKES RESERVOIR (2003546) ☆	835	2025-10-29	—	—	dossier →
▸ LAKE HUMPHREYS RES (2003587) ☆	715	2010-10-31	—	—	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
Beartown	11580	0.2	0.0	—	April 17 (23.2 in)
Grayback	11620	0.0	—	—	—
Middle Creek	11260	0.1	0.0	—	April 15 (19.2 in)
Rat Creek	11680	0.4	—	—	—
Upper Rio Grande	9370	0.1	0.0	—	March 18 (6.6 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 (1981–2026)

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 7 of the last 46 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 50% of median.

The snow never came: 1988, 1996, 2002, 2003, 2018, 2025, 2026. The snow left early: 2006, 2012, 2022.

Computed by this site from 5 SNOTEL sites’ full daily records (NRCS AWDB, back to 1981). 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 Grande at Thirty Mile Bridge

NRCS's final issue (2026-06-01) calls it even odds that at least 19 kAF arrives over 06-01 to 09-30 — 26% of a normal season; almost certainly at least 10, probably not more than 43. Our own record at this gage shows 11 kAF so far this period (partial record: 36 of 93 days). 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 43 replayed seasons (15% typical miss unadjusted vs 13% 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
10	15	19	29	43	72	11*

How good are these forecasts here? (1962–2025)

Grading every April issue against what the river then delivered, measured at this gage’s own record — 62 seasons: the median miss of the 50% forecast is 14%, with a low bias of 4%, and the observed volume landed inside the stated 10–90% band 84% 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 (1981–2025)

Across 45 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 83% 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 0.7). In warm, early-melt years the river delivered a median of 70% of a normal season, against 108% 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 — Rio Grande at Wagon Wheel Gap

NRCS's final issue (2026-06-01) calls it even odds that at least 45 kAF arrives over 06-01 to 09-30 — 25% of a normal season; almost certainly at least 22, probably not more than 81. Our own record at this gage shows 22 kAF so far this period (partial record: 36 of 93 days). 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 41 replayed seasons (12% typical miss unadjusted vs 9% 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
22	33	45	60	81	182	22*

How good are these forecasts here? (1982–2025)

Grading every April issue against what the river then delivered, measured at this gage’s own record — 42 seasons: the median miss of the 50% forecast is 12%, with a low bias of 6%, and the observed volume landed inside the stated 10–90% band 81% 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 (1981–2025)

Across 45 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 82% 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 0.8). In warm, early-melt years the river delivered a median of 75% of a normal season, against 115% 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 — SF Rio Grande at South Fork

NRCS's final issue (2026-06-01) calls it even odds that at least 17 kAF arrives over 06-01 to 09-30 — 35% of a normal season; almost certainly at least 8, probably not more than 29. Our own record at this gage shows 7 kAF so far this period (partial record: 36 of 93 days). 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 43 replayed seasons (16% 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
8	12	17	22	29	49	7*

How good are these forecasts here? (1950–2025)

Grading every April issue against what the river then delivered, measured at this gage’s own record — 74 seasons: the median miss of the 50% forecast is 16%, with a low bias of 0%, and the observed volume landed inside the stated 10–90% band 90% 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 (1981–2025)

Across 45 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 70% 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 1.0). In warm, early-melt years the river delivered a median of 75% of a normal season, against 110% 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 — Rio Grande nr Del Norte

NRCS's final issue (2026-06-01) calls it even odds that at least 65 kAF arrives over 06-01 to 09-30 — 25% of a normal season; almost certainly at least 25, probably not more than 117. Our own record at this gage shows 30 kAF so far this period (partial record: 36 of 93 days). 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 172 kAF over 04-01 to 09-30. Re-anchoring that number on this river’s own history — how its April issues have verified, the winter’s baseflow, and the district’s April 1 snowpack — moves it to 184 kAF. The river has delivered 155 kAF so far (partial record).

Computed by this site — not an NRCS number, and shown only because it earned it: replayed over 44 past seasons here (1981–2025), never seeing the year it predicts, the adjustment cut the typical April miss from 13% to 10%. 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
25	45	65	86	117	255	30*

How good are these forecasts here? (1950–2025)

Grading every April issue against what the river then delivered, measured at this gage’s own record — 75 seasons: the median miss of the 50% forecast is 13%, with a low bias of 2%, and the observed volume landed inside the stated 10–90% band 84% 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 (1981–2025)

Across 45 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 71% 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 1.0). In warm, early-melt years the river delivered a median of 64% of a normal season, against 108% 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.

Decreed rights on this network run from 1850-12-31 to 2015-09-24. Of the 20 structures with a yield estimate, the median one’s senior right was in priority 6% of a median irrigation season and 0% in a dry one. 16 abandonment screens and 184 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: 9212 across 8016 structure(s); 338 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 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 (57 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	61	8	1870-03-01
2015	365	373	1854-03-31
2016	366	344	1850-01-01
2017	365	307	1855-04-30
2018	365	427	1855-06-01
2019	365	547	1850-01-01
2020	366	523	1854-03-31
2021	365	533	1854-03-31
2022	365	291	1854-03-31
2023	365	136	1854-03-31
2024	366	105	1854-03-31
2025	365	117	1854-03-31

Why diversions stopped — call-based explanations

Sustained diversion stops matched to senior administrative calls.

• BAUER D (2000528) DWR↗☆ stopped 2025-10-22 (5+ days) — call at SANGRE CRISTO TRINCHERA curtailing 100% of its decreed rate [heuristic-strong]
• CADLE D 3 (2000559) DWR↗☆ stopped 2025-09-07 (35+ days) — call at RIO GRANDE COMPACT - LOBATOS curtailing 100% of its decreed rate [heuristic-strong]
• BILLINGS D (2000546) DWR↗☆ stopped 2025-08-29 (7+ days) — call at RIO GRANDE COMPACT - LOBATOS curtailing 96% of its decreed rate [heuristic-partial]
• BREY D (2000552) DWR↗☆ stopped 2025-08-28 (44+ days) — call at RIO GRANDE COMPACT - LOBATOS curtailing 100% of its decreed rate [heuristic-strong]
• CADLE D 1 (2000557) DWR↗☆ stopped 2025-08-17 (56+ days) — call at RIO GRANDE COMPACT - LOBATOS curtailing 100% of its decreed rate [heuristic-strong]
• BUTLER IRR D (2000556) DWR↗☆ stopped 2025-08-11 (7+ days) — call at RIO GRANDE COMPACT - LOBATOS curtailing 100% of its decreed rate [heuristic-strong]
• BELLOWS CR D 1 (2000531) DWR↗☆ stopped 2025-07-28 (21+ days) — call at RIO GRANDE COMPACT - LOBATOS curtailing 100% of its decreed rate [heuristic-strong]
• BAUER D (2000528) DWR↗☆ stopped 2025-07-27 (5+ days) — call at RIO GRANDE COMPACT - LOBATOS curtailing 100% of its decreed rate [heuristic-strong]
• BARCLAY D (2000524) DWR↗☆ stopped 2025-07-14 (106+ days) — call at RIO GRANDE COMPACT - LOBATOS curtailing 75% of its decreed rate [heuristic-partial]
• BREENE MYERS D (2000551) DWR↗☆ stopped 2025-06-30 (110+ days) — call at RIO GRANDE COMPACT - LOBATOS curtailing 57% of its decreed rate [heuristic-partial]
• BEVAN D 4 (2000541) DWR↗☆ stopped 2025-06-19 (116+ days) — call at RIO GRANDE COMPACT - LOBATOS curtailing 56% of its decreed rate [heuristic-partial]
• BENNETT CR D (2000535) DWR↗☆ stopped 2025-06-18 (29+ days) — call at RIO GRANDE COMPACT - LOBATOS curtailing 80% of its decreed rate [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.

Structure	Senior priority	Senior right: median / dry yr	Junior right: median / dry yr
USFS QP37N (2001965) DWR↗☆	1905-06-03	5.6% / 0.0%	5.6% / 0.0%
RIO GRANDE CNL (2000812) DWR↗☆	1879-11-30	50.2% / 0.0%	5.6% / 0.0%
RGWUA RECHARGE PROJECT (2001675) DWR↗☆	1959-11-01	5.6% / 0.0%	5.6% / 0.0%
USFS QP37K (2001964) DWR↗☆	1905-06-03	5.6% / 0.0%	5.6% / 0.0%
USFS QP39F (2001984) DWR↗☆	1907-03-02	5.6% / 0.0%	5.6% / 0.0%
FARMERS UNION CNL (2000631) DWR↗☆	1887-04-01	17.3% / 0.0%	5.6% / 0.0%
EMPIRE CNL (2000623) DWR↗☆	1882-08-10	33.0% / 0.0%	5.6% / 0.0%
SAN LUIS VALLEY CNL (2000829) DWR↗☆	1885-01-05	24.6% / 0.0%	5.6% / 0.0%
USFS QP37D (2001958) DWR↗☆	1905-06-03	5.6% / 0.0%	5.6% / 0.0%
USFS QP39D (2001979) DWR↗☆	1905-06-03	5.6% / 0.0%	5.6% / 0.0%
USFS QP31F (2001929) DWR↗☆	1905-06-03	5.6% / 0.0%	5.6% / 0.0%
PRAIRIE D (2000798) DWR↗☆	1872-05-01	51.6% / 0.0%	5.6% / 0.0%

Abandonment radar (16 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 ~1957 — idleness that begins before then may be unreported use, not nonuse (flagged † below).

• EAGLE D (2000613) DWR↗☆ (1875-05-05, 5.3 cfs decreed): last active 1962 — 34 years idle
• LOHR OVERFLOW SEPG D #1 (2000718) DWR↗☆ (1897-06-28, 9.0 cfs decreed): last active 1962 — 34 years idle
• WINTZ D (2000908) DWR↗☆ (1910-10-14, 2.1 cfs decreed): last active 1962 — 34 years idle
• MEADOW LAKE RES (2003547) DWR↗☆ (1916-06-01, 0.0 cfs decreed): last active 1965 — 31 years idle
• LARICK D 5 (2000708) DWR↗☆ (1874-05-01, 2.0 cfs decreed): last active 1966 — 30 years idle
• MACLEOD D 2 (2000724) DWR↗☆ (1882-05-31, 1.0 cfs decreed): last active 1970 — 26 years idle
• MACLEOD D 5 (2000727) DWR↗☆ (1878-04-01, 1.0 cfs decreed): last active 1970 — 26 years idle
• SHERIDAN NORTH D (2000841) DWR↗☆ (1883-04-01, 2.0 cfs decreed): last active 1970 — 26 years idle
• SHERIDAN SOUTH D (2000842) DWR↗☆ (1882-09-30, 3.0 cfs decreed): last active 1970 — 26 years idle
• BOWEN DRAIN DIST LAT SYS (2000549) DWR↗☆ (1922-06-21, 53.5 cfs decreed): last active 1974 — 22 years idle

Compliance screens (184 advisory flags)

Screened 342 of 8016 structures with rights (413 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.

• EMPIRE CNL (2000623) DWR↗☆: Observed p99 daily rate 516.0 cfs (max 613.0) exceeds total decreed absolute 505.9 cfs across 49601 recorded day(s).
• RIO GRANDE RES (2003554) DWR↗☆: Observed p99 daily rate 224.0 cfs (max 2039.3) exceeds total decreed absolute 3.7 cfs across 250131 recorded day(s).
• PRAIRIE DRAIN D (2000799) DWR↗☆: Observed p99 daily rate 188.0 cfs (max 216.0) exceeds total decreed absolute 40.0 cfs across 2199 recorded day(s).
• COSTILLA D (2000587) DWR↗☆: Observed p99 daily rate 134.0 cfs (max 191.0) exceeds total decreed absolute 103.3 cfs across 28368 recorded day(s).
• SANTA MARIA RES (2003558) DWR↗☆: Observed p99 daily rate 109.4 cfs (max 1696.0) exceeds total decreed absolute 3.7 cfs across 146061 recorded day(s).
• EXCELSIOR D (2000627) DWR↗☆: Observed p99 daily rate 106.0 cfs (max 154.0) exceeds total decreed absolute 89.7 cfs across 40685 recorded day(s).
• CENTENNIAL D (2000566) DWR↗☆: Observed p99 daily rate 97.0 cfs (max 132.0) exceeds total decreed absolute 82.4 cfs across 35085 recorded day(s).
• CONTINENTAL RES (2003536) DWR↗☆: Observed p99 daily rate 95.3 cfs (max 1647.6) exceeds total decreed absolute 3.7 cfs across 162004 recorded day(s).
• CHICAGO D (2000575) DWR↗☆: Observed p99 daily rate 85.0 cfs (max 196.0) exceeds total decreed absolute 66.4 cfs across 33392 recorded day(s).
• WESTSIDE D (2000903) DWR↗☆: Observed p99 daily rate 50.0 cfs (max 80.0) exceeds total decreed absolute 35.8 cfs across 22621 recorded day(s).

Seniority (top structures by decreed rate)

Structure	Senior priority date	Rights	Decreed abs (cfs)	Decreed abs (AF)	Conditional?
USFS QP37N (2001965) DWR↗☆	1905-06-03	1	2044.0	0	—
RIO GRANDE CNL (2000812) DWR↗☆	1879-11-30	23	1648.5	0	—
RGWUA RECHARGE PROJECT (2001675) DWR↗☆	1959-11-01	1	1018.0	0	yes
USFS QP37K (2001964) DWR↗☆	1905-06-03	1	960.0	0	—
USFS QP39F (2001984) DWR↗☆	1907-03-02	1	880.0	0	—
FARMERS UNION CNL (2000631) DWR↗☆	1887-04-01	10	801.4	0	—
EMPIRE CNL (2000623) DWR↗☆	1882-08-10	6	505.9	0	—
SAN LUIS VALLEY CNL (2000829) DWR↗☆	1885-01-05	13	501.0	0	yes
USFS QP37D (2001958) DWR↗☆	1905-06-03	1	447.0	0	—
USFS QP39D (2001979) DWR↗☆	1905-06-03	1	390.2	0	—
USFS QP31F (2001929) DWR↗☆	1905-06-03	1	373.2	0	—
PRAIRIE D (2000798) DWR↗☆	1872-05-01	19	367.0	0	—
MONTE VISTA CNL (2000753) DWR↗☆	1882-05-31	12	340.8	0	—
USFS QP37B (2001956) DWR↗☆	1905-06-03	1	324.6	0	—
USFS QP37H (2001962) DWR↗☆	1907-03-02	1	293.4	0	—

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

Water-court filings this month (division-wide)

1 application in the 2026-06 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 2026-08-31 (0 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 1 filings, with excerpts

Case	What it asks	County	Excerpt
2026CW3011	make absolute	CONEJOS	CASE NUMBER 2026 CW3011 Application to make conditional water right absolute in Conejos County Name, address, email address of applicant: Tyler Huffaker, PO Box 54, Manassa, CO 81141 tophillquarterhorses@gmail.com (atty Erich Schwiesow PO Box 1974, Alamosa, CO…

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.

Plan	Type	Status	Expires	Structure	Documents
BASSI NORTH FARM LLC	37-92-308(5) PLANS LESS THAN 5 YEARS	Approved	2026-03-31	—	plan file
PINE RIVER WEMINUCHE PASS DITCH SD 2 3 6	37-92-308(5) PLANS LESS THAN 5 YEARS	Approved	2026-04-30	—	plan file
SUBDISTRICT NO 2 SQUAW PASS	37-92-308(4) PLAN PENDING COURT APPLICATION	Approved	—	—	plan file
COBLENTZ WELLS	37-92-308(4) PLAN PENDING COURT APPLICATION	Division Review	—	—	plan file
DEACON FAMILY INVESTMENTS LP	37-92-308(5) PLANS LESS THAN 5 YEARS	Division Review	—	—	plan file
MEADOW GLEN DITCH - WEBB	37-92-308(5) PLANS LESS THAN 5 YEARS	Division Review	—	—	plan file
SUSTAINABLE WATER AUGMENTATION GROUP (SWAG) - CASE NO 23CW3015	37-92-308(4) PLAN PENDING COURT APPLICATION	Additional Info Needed	—	—	plan file
SD5 BEAVER RESERVOIR	37-92-308(5) PLANS LESS THAN 5 YEARS	Expired	2025-04-30	—	plan file
MONTE VISTA WATER USERS ASSN	37-92-308(5) PLANS LESS THAN 5 YEARS	Withdrawn	—	—	plan file

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.

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
Simulate

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