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GROSS RES

Structure dossier · WDID 0604199 · RESERVOIR · SOUTH BOULDER CREEK · DWR record · probably DENVER WATER BOARD’s (matched on DWR’s contact or an EPA intake name; verify below)

Gross Res is a reservoir on South Boulder Creek 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 05:36 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.

The record and the river

In short

GROSS RES holds 26 decreed rights on SOUTH BOULDER CREEK. As of 2026-09-27, 25 of them are out of priority under a call at admin 3622.00000 placed by HOWELL DITCH. Its 1 most senior right, back to 1859-10-01, keeps diverting. 7 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 46,089 acre-feet. It was a party to 4 court cases that also touched 16 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.

Current administration

● Junior rights called out — call at RURAL DITCH (BOULDER CREEK, priority 1862-05-09).

● Junior rights called out — call at HOWELL DITCH (BOULDER CREEK, priority 1859-12-01).

Which of its rights are out of priority?

Under today's controlling call (HOWELL DITCH, priority 1859-12-01): 25 of this structure's 26 rights are out of priority now. (7 call(s) state no district and sit outside this one — not judged, not assumed.) In the 5 past years most like this one (2018, 2021, 2012, 2016, 2005), 5 of the rights shown below were out at least one week in at least one analog year.

Right (priority)NowAnalog years outMajority out by
1859-10-01 3561 ● in priority 0 of 5 —
1863-05-01 4869 ● out 5 of 5 2026-09-27
1865-02-01 5511 ● out 5 of 5 2026-09-27
… 20 more rights between these …
2016-11-28 60963 ● out 5 of 5 2026-09-27
2010-02-24 60997 ● out 5 of 5 2026-09-27
2010-10-24 60997 ● out 5 of 5 2026-09-27
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 BOULDER CREEK BELOW GROSS RESERVOIR around 2026-09-27 (the newest reading on file) — currently 7% of that gage's own median for this window — to pick the 5 most similar past years with complete administration records (2004–2026). 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 1859-10-01 — 18th most senior of the 1867 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: 0602415 (1859-10-01). Immediately behind: SMITH GOSS DITCH (1859-11-15).

On SOUTH BOULDER CREEK at river mile 1.2, it is 6th of 59 down the reach. Immediately upstream: LAKE PACTOLUS. Immediately downstream: DENVER POWER CONDUIT 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 (26)

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
3561.00000 1859-10-011882-06-02 0.0 cfs 0.0 1.725 cfs Irrigation, Municipal +7 90CW0108, 97CW0195
4869.00000 1863-05-011882-06-02 0.0 cfs 0.0 0.043 cfs Irrigation, Municipal +8 90CW0108, 80CW0468
5511.00000 1865-02-011882-06-02 0.0 cfs 0.0 0.064 cfs Irrigation, Municipal +8 90CW0108, 80CW0468
5570.00000 1865-04-011882-06-02 0.0 cfs 0.0 2.5425 cfs Irrigation, Municipal +8 85CW0119, 80CW0468 +1
5935.00000 1866-04-011882-06-02 0.0 cfs 0.0 1.3203 cfs Irrigation, Municipal +8 05CW0295, 80CW0468 +1
5979.00000 1866-05-151882-06-02 0.0 cfs 0.0 0.044 cfs Irrigation, Municipal +8 90CW0108, 80CW0468
5996.00000 1866-06-011882-06-02 0.0 cfs 0.0 0.017 cfs Irrigation, Municipal +8 80CW0468, 90CW0108
7457.00000 1870-06-011882-06-02 0.0 cfs 0.0 3.132 cfs Irrigation, Municipal +7 90CW0108, 97CW0195
7579.00000 1870-10-011882-06-02 0.0 cfs 0.0 1.7919 cfs Irrigation, Municipal +8 80CW0468, 85CW0119 +1
8141.00000 1872-04-151882-06-02 0.0 AF 0.0 79.0 AF Irrigation, Municipal +5 85CW0119, W8348
8553.00000 1873-06-011882-06-02 0.0 AF 0.0 250.0 AF Irrigation, Municipal +5 W8348, 85CW0119
11567.00000 1881-09-011907-03-13 0.0 AF 0.0 1.5 AF Irrigation, Municipal +4 85CW0119
12724.00000 1884-11-011907-03-13 0.0 AF 0.0 52.5 AF Irrigation, Municipal +4 85CW0119
15386.00000 1892-02-151907-03-13 0.0 AF 0.0 180.2 AF Irrigation, Municipal +4 85CW0119
17441.00000 1897-10-011907-03-13 0.0 AF 0.0 172.2 AF Irrigation, Municipal +4 85CW0119
20890.20624 1906-06-201907-11-03 0.0 AF 0.0 436.3 AF Irrigation, Municipal +4 85CW0119
27930.23981 1915-08-291953-09-28 0.0 AF 0.0 25.0 AF Irrigation, Municipal +4 85CW0119
34828.00000 1945-05-101953-09-28 41811.0 AF 71267.0 AF — Storage, Irrigation +8 86CW0142, CA12111
47847.00000 1980-12-311980-12-31 0.0 cfs 0.0 16.0 cfs Irrigation, Municipal +6 93CW0025, 79CW0387
49669.00000 1985-12-271985-12-31 0.0 cfs 0.0 20.5 cfs Irrigation, Municipal +7 79CW0387, 93CW0025
51269.00000 1990-05-151990-12-31 0.0 cfs 0.0 8.0 cfs Irrigation, Municipal +7 90CW0108
53872.00000 1997-06-301997-12-31 0.0 cfs 0.0 8.0 cfs Irrigation, Municipal +7 97CW0195
58825.00000 2011-01-212011-12-31 0.0 cfs 0.0 8.0 cfs Irrigation, Municipal +7 05CW0295
60963.00000 2016-11-282016-12-31 0.0 cfs 0.0 21.9 cfs Municipal 16CW3160
60996.58494 2010-02-242017-12-31 0.0 AF 5000.0 AF — Municipal, Minimum streamflow 17CW3212
60996.58736 2010-10-242017-12-31 0.0 cfs 0.0 100.0 cfs Municipal 16CW3160

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.

Water-court filings naming this structure

4 applications in the monthly water-court resumes explicitly reference this WDID. The resume is the earliest public notice of a new claim (C.R.S. 37-92-302) — years before anything reaches the decree record below. Most applications name structures by name rather than WDID, so absence here is weak evidence of absence.

MonthCaseWhat it asksOppose byExcerpt
2026-08 2026CW3125 reasonable diligence 2026-10-31 (17d left) CASE NUMBER 2026CW3125 (90CW108) (99CW125) (12CW72) (20CW3017) APPLICATION FOR FINDING OF REASONABLE DILIGENCE IN BOULDER COUNTY . 1. Name, Mailing Address, Phone Number, and E -mail Address of Applicant . CITY OF LAFAYE…
2026-06 2026CW3093 reasonable diligence closed 2026-08-31 CASE NUMBER 20 26CW3093 (05CW295) (19CW3201) APPLICATION FOR FINDING OF REASONABLE DILIGENCE IN BOULDER COUNTY. 1. Name, Mailing Address, Phone Number, and E -mail Address of Applicant . CITY OF LAFAYETTE , c/o Cari Bisc…
2025-10 2025CW3137 reasonable diligence closed 2025-12-31 CASE NUMBER 2025CW3137 (97CW195) (06CW150) (19CW3020) APPLICATION FOR FINDING OF REASONABLE DILIGENCE IN BOULDER COUNTY – 1. Name, Mailing Address, Phone Number, and E-mail Address of Applicant. CITY OF LAFAYETTE, c/o Ca…
2025-04 2025CW3049 reasonable diligence closed 2025-06-30 CASE NUMBER 2025CW3049 (79CW387) (93CW025) (01CW295) (02CW281) (18CW3035) APPLICATION FOR FINDING OF REASONABLE DILIGENCE IN BOULDER COUNTY. – 1. Name, Mailing Address, Phone Number, and E-mail Address of Applicant. CITY…

Source: Judicial Branch combined monthly resumes (archive), indexed nightly; WDIDs attached only when a 7-digit token in the filing matches DWR’s structure inventory.

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 3561.00000 · never out of priority in these seasons
AprMayJunJulAugSep
middle right · admin 15386.00000 · peaks at 11 of 11 seasons
AprMayJunJulAugSep
most junior right · admin 60996.58736 · peaks at 11 of 11 seasons
AprMayJunJulAugSep

Snow sets the clock here. In the driest third of snow years (3 seasons), the call settled in for the season around June 3; in 1 of them it never lifted at all. In the middle third (5 seasons), the call settled in for the season around June 17 (June 17 to June 24 across those years); in 2 of them it never lifted at all. In the wettest third (3 seasons), the call settled in for the season around June 24; in 2 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 46,089 AF. Its most recent year on record, 2025, came in at 46,089 AF — 100% of that, and 8th 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 54,015 14th lowest of 15 · 117% of median 51,914 365 850.0
2012 41,312 7th lowest of 15 · 90% of median 40,257 366 269.0
2013 62,619 15th lowest of 15 · 136% of median 54,362 365 858.0
2014 35,552 3rd lowest of 15 · 77% of median 39,002 365 502.0
2015 38,407 4th lowest of 15 · 83% of median 37,032 361 523.0
2016 40,440 5th lowest of 15 · 88% of median 45,801 364 394.0
2017 49,054 11th lowest of 15 · 106% of median 44,553 355 494.0
2018 50,244 12th lowest of 15 · 109% of median 52,241 365 766.0
2019 50,599 13th lowest of 15 · 110% of median 42,324 365 707.0
2020 48,635 10th lowest of 15 · 106% of median 65,021 366 585.0
2021 41,071 6th lowest of 15 · 89% of median 39,250 293 640.3
2022 48,101 9th lowest of 15 · 104% of median 91,504 363 298.0
2023 27,867 1st lowest of 15 · 60% of median 78,542 365 246.4
2024 32,646 2nd lowest of 15 · 71% of median 76,264 366 402.1
2025 46,089 8th lowest of 15 · 100% of median 73,169 304 396.8

How good is our record of it?

Grade A (10/10 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 26 right(s), seniority decoded
diversion record current 15894 measured days, newest 331 day(s) before the data's end (DWR publishes ~1 year in arrears)
record continuity continuous 100% of the irrigation seasons in 1974-2025 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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