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GRASS VALLEY RESERVOIR
Structure dossier · WDID 3903505 · 3 · HARVEY GAP · DWR record
Where this page's figures come from
Generated 2026-08-28 02:12 by Hydrohistorian. Sources: DWR HydroBase snapshot HydroBase_CO_20260707 (history) + CDSS REST (current), USGS NWIS cross-checks. Engine v0.5.0 (2deb1d7) — every figure regenerates from this named code version and data image.
Where it sits
Location as DWR records it. Faint dots are the neighbouring water; click any to open it.
Which of its rights are out of priority?
Not computable for this structure: this structure is not on the modelled flow network, so no reference gage can honestly stand in for it.
Where it sits in line
Priority 1891-04-01 — 121st most senior of the 1758 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: NOTT NO 2 DITCH (1890-09-29). Immediately behind: PURDY DITCH (1890-04-05).
Decreed rights (2)
| 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. | Units | UsesWhat the court said this water may be used for -- irrigation, municipal supply, augmentation and so on. | Case |
|---|---|---|---|---|---|---|---|
| 15667.15066 | 1891-04-01 | 1893-04-03 | 3902.0 | 0.0 | A | IRRDOMAUG | RES5 |
| 37503.35321 | 1946-09-15 | 1966-11-10 | 3087.2 | 0.0 | A | IRRDOM | 301 |
Legal record & documents
6 decreed actions on record across
4 court cases:
CA4914, CA0519, 02CW0057, 00CW0036.
Every case, dated
| Case | Actions | Latest adjudication | Types |
|---|---|---|---|
CA4914 | 1 | 1966-11-10 | S |
CA0519 | 1 | 1893-04-03 | S |
02CW0057 | 2 | 1893-04-03 | S |
00CW0036 | 2 | 1893-04-03 | S |
DWR's own records for this structure: net amounts · transactions & adjudication history · scanned decrees (search a case number there for the imaged document). On this site: the district's full legal picture →
Recorded use (last 15 years on record)
In a median year this structure has a recorded diversion of 1,733 AF. Its most recent year on record, 2024, came in at 992 AF — 57% 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.
| Year | Diverted (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 record | Released (AF) | Days recorded | Peak (cfs) |
|---|---|---|---|---|---|
| 2010 | 1,794 | 9th lowest of 15 · 104% of median | 830 | 365 | 46.5 |
| 2011 | 2,016 | 12th lowest of 15 · 116% of median | 919 | 365 | 39.3 |
| 2012 | 3,602 | 14th lowest of 15 · 208% of median | 4,202 | 366 | 27.6 |
| 2013 | 3,799 | 15th lowest of 15 · 219% of median | 3,229 | 365 | 28.0 |
| 2014 | 1,921 | 10th lowest of 15 · 111% of median | 766 | 365 | 35.0 |
| 2015 | 2,027 | 13th lowest of 15 · 117% of median | 863 | 365 | 32.2 |
| 2016 | 1,733 | 8th lowest of 15 · 100% of median | 898 | 366 | 33.9 |
| 2017 | 1,506 | 4th lowest of 15 · 87% of median | 1,068 | 365 | 39.5 |
| 2018 | 1,626 | 7th lowest of 15 · 94% of median | 518 | 365 | 32.1 |
| 2019 | 1,484 | 3rd lowest of 15 · 86% of median | 880 | 365 | 33.0 |
| 2020 | 1,591 | 6th lowest of 15 · 92% of median | 846 | 366 | 33.9 |
| 2021 | 1,422 | 2nd lowest of 15 · 82% of median | 558 | 365 | 33.6 |
| 2022 | 1,531 | 5th lowest of 15 · 88% of median | 573 | 365 | 29.8 |
| 2023 | 1,966 | 11th lowest of 15 · 113% of median | 755 | 365 | 47.2 |
| 2024 | 992 | 1st lowest of 15 · 57% of median | 1,005 | 305 | 24.4 |
Trends for this structure
Recorded use is falling over its last 15 recorded years (-62 AF/yr, Mann-Kendall p=0.008).
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
| Check | State | Detail |
|---|---|---|
| identity | complete | name, type, and water source all on file |
| decreed rights | on file | 2 right(s), seniority decoded |
| diversion record | present | 5844 measured days; currency unknown (no data-coverage date to compare against) |
| record continuity | continuous | 100% of the irrigation seasons in 2008-2024 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.