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Upper South Platte

Division 1 · Water District 23 · As of 2026-09-08 13:50 MDT · 7 days ago
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Upper South Platte on the ground — the ditches, wells, reservoirs and gages of Water District 23 · clicktap anything for its record

Browse this district’s ditches, gages, reservoirs, wells and springs as a list.

35% of normal flow, week of 2026-08-31
25 calls active on it right now

The South Platte River is well below normal for late August -- 35% of normal flow. 25 calls stand against it right now; the most senior right calling dates to 1860. This year's runoff outlook, issued 2026-06-01, called for 41% of normal.

Drought

Source Our computation, no independent reference · computed here from the screened DWR record Source Independent agency measurement · fetched 2026-09-08 · verify at U.S. Drought Monitor ↗

Right now

This is the 34th-driest week 36 in 96 years of record at SOUTH PLATTE RIVER NEAR LAKE GEORGE, CO. (as of 2026-08-31; this week’s flow sits at the 35th 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, Park County is 15% in D4 exceptional drought (2026-09-08).

Every year since 1929, week by week

Each thin row is a year at SOUTH PLATTE RIVER NEAR LAKE GEORGE, CO.; 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 36 weeks recorded so far, 2026’s weekly trace most resembles 2023 (mean gap 14.8 percentile points; next closest 2018 (15.6), 1992 (17.7)). 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 Boulder, Park 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 1957 — 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 (754 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

DroughtSpanWeeks Trough percentileFlows recovered Water table back
the 2002 drought 2003-07-21 → 2004-02-16 30 18th (2003-09-22) 49 weeks —
unnamed dry spell 1983-04-25 → 1983-11-21 30 17th (1983-07-11) 7 weeks —
the 1981 drought 1981-07-06 → 1981-12-07 22 25th (1981-08-31) 35 weeks —
the 1977 drought 1977-09-12 → 1979-03-12 78 12th (1978-08-07) 13 weeks —
unnamed dry spell 1974-09-16 → 1975-05-26 36 16th (1974-10-28) 8 weeks —
unnamed dry spell 1972-08-28 → 1973-05-14 37 16th (1972-12-25) 4 weeks —
unnamed dry spell 1965-11-29 → 1968-08-12 141 9th (1967-07-31) 48 weeks —
the 1963-64 drought 1962-11-12 → 1963-08-19 40 18th (1963-02-04) 1 week —
unnamed dry spell 1960-08-29 → 1961-10-16 59 14th (1961-01-30) 5 weeks —
unnamed dry spell 1958-10-27 → 1959-12-14 59 9th (1958-12-22) 16 weeks —
the 1950s drought 1956-11-26 → 1957-04-29 22 25th (1956-12-31) 55 weeks —
the 1950s drought 1953-12-14 → 1954-05-03 20 22nd (1954-02-08) 7 weeks —
the 1950s drought 1953-02-23 → 1953-08-03 23 27th (1953-05-25) 46 weeks —
the 1950s drought 1950-09-11 → 1951-04-23 32 23rd (1950-10-23) 59 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.

What drought has cost here

Since 1994, federal crop insurance has paid $182,449 in drought-caused claims across Boulder, Park counties — 4.2% of all insured crop losses there. The worst year was 2022 ($70,070).

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

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.

Snowpack — no snow on the ground at 3 SNOTEL sites — normal for the date; the snow year begins in October and typically peaks around May 2. Runoff outlook — Antero Reservoir Inflow: even odds of at least 5 kAF over 06-01 to 09-30 — 46% of a normal season, per NRCS, issued 2026-06-01 — the season’s final; new forecasts begin in January. Runoff outlook — Spinney Mountain Reservoir Inflow: even odds of at least 16 kAF over 06-01 to 09-30 — 37% of a normal season, per NRCS, issued 2026-06-01 — the season’s final; new forecasts begin in January. Runoff outlook — Elevenmile Canyon Reservoir Inflow: even odds of at least 18 kAF over 06-01 to 09-30 — 41% 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 siteElev (ft)SWE (in)Median (in)% of medianTypical peak
Buckskin Joe11160 0.00.0 — May 2 (12.6 in)
Michigan Creek10700 0.00.0 — April 26 (13.2 in)
Rough And Tumble10420 0.00.0 — April 24 (8.3 in)

Antero Reservoir Inflow — 06-01 to 09-30 volume, thousand acre-feet (chance the volume is AT LEAST this):

90%70%50%30%10%Normal
24567 11

Spinney Mountain Reservoir Inflow — 06-01 to 09-30 volume, thousand acre-feet (chance the volume is AT LEAST this):

90%70%50%30%10%Normal
712161822 43

Elevenmile Canyon Reservoir Inflow — 06-01 to 09-30 volume, thousand acre-feet (chance the volume is AT LEAST this):

90%70%50%30%10%Normal
814182125 45

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.

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