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ELEVEN MILE RES

Structure dossier · WDID 2303965 · RESERVOIR · SOUTH PLATTE RIVER · DWR record

Eleven Mile Res is a reservoir on South Platte River in Colorado. This page is its public record: the water it has a right to, whether it may take it today, and its history, compiled from the Colorado Division of Water Resources.

Source DWR administrative record · verify at DWR structure ↗ Source DWR administrative record · verify at DWR diversion records ↗ Source Our computation, scored against a reference · scored against DWR's call analysis, see /methods

Where this page's figures come from

Generated 2026-10-14 10:38 by Hydrohistorian. Sources: DWR HydroBase snapshot HydroBase_CO_20260928 (history) + CDSS REST (current), USGS NWIS cross-checks. Engine v0.5.0 (dd58e60) — every figure regenerates from this named code version and data image.

Who owns it

DWR’s own records name no owner for a ditch, reservoir or well, so this comes from the source shown and can be out of date. Organisations only: a private landowner’s name is never listed.

In short

ELEVEN MILE RES holds 12 decreed rights on SOUTH PLATTE RIVER. As of 2026-10-02, 11 of them are out of priority under a call at admin 5112.00000 placed by SOUTH PLATTE RIVER AT WATERTON. Its 1 most senior right, back to 1860-12-28, keeps diverting. 5 further calls state no district and sit outside this one, so they are counted here rather than assumed either way. In a median year over its last 15 recorded years it diverts 10,952 acre-feet. It was a party to 1 court cases that also touched 7 other structures.

Assembled from the figures on this page — every number above is checked against them before it is shown (11 checked). The detail, with its method, is in the cards below.

Download this structure

Everything on this page as data you can work with — and a README that makes it citable: the HydroBase snapshot it was built from, the build commit, what every column means, the method behind each derived figure, and that method's stated limits.

⇩ Full record (.zip) Print / save as PDF

Or one table at a time: rights.csv · annual_use.csv · curtailment_now.csv · court_cases.csv · co_parties.csv · call_climatology.csv

What is in the bundle
  • rights.csv — every decreed right, most senior first, with admin numbers, dates, amounts, uses and case numbers.
  • annual_use.csv — recorded diversion by year, with releases accounted separately.
  • curtailment_now.csv — each right's current priority status and how often it was out across analog years.
  • court_cases.csv — the cases attached to its rights.
  • co_parties.csv — the other structures that were parties to those cases. Not available anywhere else.
  • call_climatology.csv — how often each right has been out of priority by week of season, with confidence intervals and the seasons the record could actually judge.
  • README.txt — provenance, methods, limits, disclaimer, and links back to DWR's own records for verification.

Where it sits

Location as DWR records it (storage). Faint dots are the neighbouring water; click any to open it.

Dam safety

Dam ELEVEN MILE CANYON (completed 1932)
Hazard class High
Condition at last inspection Satisfactory (2026-05-13)
Storage restriction None on file
Normal storage 97,800 AF
Physical status Active
Emergency action plan Yes

Source: DWR Dam Safety’s jurisdictional-dam inventory (damsafety/damsafetydaminfojd), refreshed weekly. Joined on this structure’s own WDID as DWR records it on the dam. Hazard class describes the consequence of failure, not the likelihood of it. DWR’s dam record.

Current administration

● Junior rights called out — call at SOUTH PLATTE RIVER COMPACT (SOUTH PLATTE RIVER, priority 1897-06-13).

● Junior rights called out — call at SOUTH PLATTE RIVER AT WATERTON (SOUTH PLATTE RIVER, priority 1863-12-30).

● Junior rights called out — call at CHATFIELD RESERVOIR (SOUTH PLATTE RIVER, priority 1865-12-30).

● Junior rights called out — call at STERLING IRR CO DITCH 1 (SOUTH PLATTE RIVER, priority 1901-02-16).

Which of its rights are out of priority?

Under today's controlling call (SOUTH PLATTE RIVER AT WATERTON, priority 1863-12-30): 11 of this structure's 12 rights are out of priority now. (5 call(s) state no district and sit outside this one — not judged, not assumed.) In the 5 past years most like this one (2012, 2019, 2014, 2020, 2017), 9 of the rights shown below were out at least one week in at least one analog year.

Right (priority)NowAnalog years outMajority out by
1860-12-28 4015 ● in priority 0 of 5 —
1880-03-15 11032 ● out 0 of 5 —
1880-06-20 11129 ● out 0 of 5 —
1882-05-01 11809 ● out 1 of 5 —
1885-05-20 12924 ● out 1 of 5 —
1885-06-01 14536 ● out 2 of 5 —
1889-07-01 14536 ● out 2 of 5 —
1895-10-09 16718 ● out 2 of 5 —
1926-07-10 27949 ● out 5 of 5 2026-10-02
1929-12-31 29219 ● out 5 of 5 2026-10-02
1957-10-07 39361 ● out 5 of 5 2026-10-02
1957-12-09 39424 ● out 5 of 5 2026-10-02
How this table is built, and what it is not

“Now” compares each right's admin number with today's most senior applicable active call. The outlook uses flows at SOUTH PLATTE RIVER NEAR LAKE GEORGE, CO. around 2026-10-02 (the newest reading on file) — currently 113% of that gage's own median for this window — to pick the 5 most similar past years with complete administration records (2011–2026). Only calls that verifiably apply count: DWR's own district statements in the call's set comments, a caller located in this district, or — on the same stream, where DWR records both stream miles (measured from the mouth) — a caller DOWNSTREAM of this structure. An upstream senior cannot demand water this diversion never deprives it of. Calls that state nothing and sit elsewhere are counted as unjudged rather than assumed, which also means the verified record is shorter than the raw one: early calls rarely state districts. For each week it finds the most senior call then in force; a right is out in that week exactly when that call is senior to it, which is why one line prices every right and juniors can be out while seniors keep diverting. “Majority out by” is the first week out in more than half the analog years. A frequency among named historical years, not a probability from a model, and not a forecast of what the division engineer will do. It says how often years whose flow resembled this one were under a call senior to this right in a given week. Snowpack, storage, and the actual administrative decisions of a given season are not modelled. Check the analog years listed: if they do not resemble this year to you, the outlook does not either.

Where it sits in line

Priority 1860-12-28 — 18th most senior of the 21886 structures with decreed rights in this water districtDWR's administrative subdivision of a river basin; the unit calls are usually stated in..

Under prior appropriationColorado's rule for sharing water: first in time, first in right. Age decides, not proximity or need., everything ahead of it in this line is satisfied in full before it receives any water. Immediately ahead: ANTERO RES (1860-12-28). Immediately behind: CHEESMAN RES (1860-12-28).

On MAINSTEM at river mile 20.8, it is 217th of 890 down the reach. Immediately upstream: VA & TC'S POND. Immediately downstream: SADDLE MOUNTAIN RES 1.

Position on the modelled network, not a claim about whose water this is — a stream carries water from many rights at once, and diverted water returns to it.

Decreed rights (13)

Admin noDWR's numeric encoding of a water right's seniority. Smaller is more senior; the integer part counts days from 1849-12-31 to the date that ranks the right. AppropriatedWhen water was first put to beneficial use. It sets seniority unless a prior adjudication date is later. AdjudicatedWhen the water court confirmed the right. A use decreed in 1975 was not a decreed use in 1955, however old the appropriation is. AbsoluteA right actually put to use, as opposed to conditional -- a placeholder for a use not yet made. ConditionalA right reserving a place in line for a use not yet made; it must be diligently pursued or it lapses. Alt-pointAn absolute amount decreed at another structure that may be diverted here instead -- an alternate point of diversion or an exchange. DWR calls this the APEX amount; a right showing 0.0 absolute but an alt-point amount is exercised here under another structure's decree. Decreed forWhat the court said this water may be used for -- irrigation, municipal supply, augmentation and so on.Case
4015.00000 1860-12-281883-12-10 0.0 cfs 0.0 6.5 cfs Irrigation, Municipal 20CW3200
4015.00000 1860-12-281883-12-10 0.0 AF 0.0 1790.28 AF Irrigation, Municipal 20CW3200
11032.00000 1880-03-151889-10-18 0.0 cfs 0.0 2.4 cfs Municipal, All beneficial uses 88CW0263
11129.00000 1880-06-201889-10-18 0.0 cfs 0.0 2.0 cfs Municipal, All beneficial uses 88CW0263
11809.00000 1882-05-011889-10-18 0.0 cfs 0.0 1.5 cfs Municipal, All beneficial uses 88CW0262
12924.00000 1885-05-201889-10-18 0.0 cfs 0.0 2.6 cfs Municipal, All beneficial uses 88CW0263
14536.12936 1885-06-011913-05-22 0.0 cfs 0.0 3.5 cfs Municipal, All beneficial uses 88CW0263
14536.14427 1889-07-011896-05-28 0.0 cfs 0.0 5.7 cfs Municipal, All beneficial uses 88CW0262
16718.00000 1895-10-091913-05-22 0.0 cfs 0.0 6.7 cfs Municipal, All beneficial uses 88CW0262
27949.00000 1926-07-101953-03-24 81917.0 AF 0.0 — Irrigation, Municipal +2 CA3286
29219.00000 1929-12-311953-03-24 81917.0 AF 0.0 — Irrigation, Municipal +2 CA3286
39361.00000 1957-10-071972-04-27 15862.0 AF 0.0 — Municipal, Industrial +2 CA3701
39424.00000 1957-12-091972-04-27 0.0 AF 17810.1 AF — Municipal, Industrial +2 CA3701

Amounts marked cfs are flow rates; AF are stored volumes (storage rights are decreed in acre-feet). An absolute amount of 0.0 beside an alt-point amount is not a dead right: the water is decreed at another structure, and that row records permission to divert it here instead (an alternate point or exchange). A case listing several numbers reflects the original decree plus later change cases.

Filings that would move water above this headgate

1 water-court application in the monthly resumes names a structure on SOUTH PLATTE RIVER upstream of this headgate. A new right, exchange or change of use up there changes what arrives down here — the resume is the public notice, and the opposition window is how anyone affected answers it.

MonthCaseWhat it asksUpstream structuresOppose by
2026-06 2026CW3096 reasonable diligence SPINNEY MTN RESERVOIR (12.4 mi up) 2026-08-31

Judged on this structure’s own named stream only — a filing on a tributary that joins upstream is not judged here. Filings that name structures only in prose, without a WDID, are invisible to this card. Reading aid, not legal advice; the deadline is computed from C.R.S. 37-92-302(3), and the court’s own notice controls.

How often is it out of priority?

Across the 11 seasons whose call record is complete enough to judge this structure (2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023, 2024, 2025, 2026), week by week from April.

most senior right · admin 4015.00000 · never out of priority in these seasons
AprMayJunJulAugSep
middle right · admin 14536.14427 · peaks at 10 of 11 seasons
AprMayJunJulAugSep
most junior right · admin 39424.00000 · peaks at 10 of 11 seasons
AprMayJunJulAugSep

Snow sets the clock here. In the driest third of snow years (3 seasons), 2 seasons stayed under call throughout and 0 ended free. In the middle third (5 seasons), the call settled in for the season around July 8 (June 24 to July 8 across those years); in 3 of them it never lifted at all. In the wettest third (3 seasons), the call settled in for the season around July 8 (May 6 to July 8 across those years); in 1 of them it never lifted at all.

Snow years ranked by the district’s April 1 snow-water percentile across 3 SNOTEL sites; 11 seasons carry both a snow reading and a judgeable call record. How the past played out, not a forecast.

Why only 11 seasons, and what the bars mean

Each bar is one week: how many of those seasons that right was out of priority under a call this site can lawfully attribute to this structure. Green is never, red is every season on record.

The short record is a property of DWR's data, not of the river. A call only counts against a structure when we can establish it applies — by the districts named in its set comments, or by stream mile on the same source. DWR did not begin stating affected districts routinely until about 2015: fewer than one call in ten can be judged before then, against roughly two in three since. A season we cannot judge is not a season without calls, so it is dropped rather than counted as quiet — 12 seasons dropped here.

This is a frequency over past seasons, not a forecast. It says nothing about what the division engineer will do this year.

Recorded use (last 15 years on record)

Years far under the decreed amount? That gap has a name — paper water vs. wet water, explained on this structure.

In a median year this structure has a recorded diversion of 10,952 AF. Its most recent year on record, 2025, came in at 1,546 AF — 14% of that, and 1st lowest of the 15 years with a recorded volume.

This structure records both diversions and reservoir releases — they are separate water movements and are accounted separately below.

YearDiverted (AFA volume: one acre covered a foot deep, about 326,000 gallons -- roughly a suburban household's outdoor use for a year.)Compared with its own recordReleased (AF)Days recordedPeak (cfs)
2011 12,184 11th lowest of 15 · 111% of median 11,910 176 176.0
2012 3,798 2nd lowest of 15 · 35% of median 4,484 154 170.0
2013 8,391 6th lowest of 15 · 77% of median 8,833 123 241.0
2014 11,688 9th lowest of 15 · 107% of median 12,202 200 192.5
2015 31,361 15th lowest of 15 · 286% of median 26,202 224 418.0
2016 6,366 4th lowest of 15 · 58% of median 6,731 211 207.0
2017 11,698 10th lowest of 15 · 107% of median 11,421 263 347.5
2018 8,897 7th lowest of 15 · 81% of median 9,365 246 139.0
2019 14,499 14th lowest of 15 · 132% of median 14,162 237 314.1
2020 10,952 8th lowest of 15 · 100% of median 14,319 211 139.0
2021 12,384 12th lowest of 15 · 113% of median 9,925 201 138.7
2022 8,183 5th lowest of 15 · 75% of median 7,325 164 138.9
2023 4,874 3rd lowest of 15 · 44% of median 5,561 166 142.8
2024 12,508 13th lowest of 15 · 114% of median 12,130 194 450.0
2025 1,546 1st lowest of 15 · 14% of median 1,498 126 17.0

How good is our record of it?

Grade A (9/10 points) — the components below are the finding; the letter alone is not.

The rubric, component by component
CheckStateDetail
identity complete name, type, and water source all on file
decreed rights on file 13 right(s), seniority decoded
diversion record current 8744 measured days, newest 366 day(s) before the data's end (DWR publishes ~1 year in arrears)
record continuity patchy 56% of the irrigation seasons in 1952-2025 carry measured days
published-record stability stable no upstream revisions recorded against this structure

Advisory reading aid on public data — not an administrative or legal conclusion, not a title opinion, and not a substitute for DWR administration or an engineer's analysis. Methodology review status is disclosed at hydrohistorian's basin pages.

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