Deerfield Reservoir water level — South Dakota
Deerfield Reservoir in South Dakota was last measured at 4.49 ft (datum NGVD29), as of Aug 31, 2026, 2:00 AM (UTC-06:00) (USGS Water Services). Over its recent trend window the level has been falling (−0.5 ft). This reading is provisional and subject to revision.
- % of conservation pool full
- Not reported
- Storage
- Not reported
- Recent trend
- ↓Falling
−0.5 ft over the trend window
Recent trend
Readings this station published between Jun 2, 2026 and Aug 31, 2026 — a 89-day window — downsampled for display.
Data: USGS Water Services (waterservices.usgs.gov) and USACE CWMS Data (cwms-data.usace.army.mil), retrieved 2026-08-31. Both public domain (a work of the U.S. Government, 17 U.S.C. §105).
Source: USGS site 06409500, retrieved Aug 31, 2026, 8:24 AM (UTC+00:00). Official page for this lake →
About this gauge's record
This site's drainage basin covers approximately 92 sq mi of contributing watershed.
The dam behind Deerfield Reservoir
Deerfield Reservoir is held back by Deerfield Dam (also recorded as Deerfield Lake) , an earthfill embankment, holding the pool back by sheer mass and an impervious core rather than by the strength of concrete , standing 171 ft high and running 825 ft along its crest , built across CASTLE CREEK in Pennington County , near RAPID CITY . It was completed in 1947 and modified in 1984H;1984S , and is owned by BUREAU OF RECLAMATION (a federal owner) .
Its recorded primary purpose is fish and wildlife pond — it is managed for habitat rather than yield . It also serves fish and wildlife pond;irrigation;water supply.
Its spillway is ungated: once the pool reaches the crest, water leaves on its own and the operator cannot hold it back. The spillway opening is 120 ft wide.
NID classes it high hazard potential. That describes what a failure would cost downstream — loss of life would be expected — and says nothing about how likely a failure is, or what condition the dam is in.
At its normal pool the reservoir covers about 423 acres. NID records a maximum storage of 42,310 acre-ft against a normal storage of 15,655 acre-ft. Its maximum discharge capacity is 103,400 cubic feet per second. It is regulated by DENR.
Dam facts: National Inventory of Dams record SD01138 , filed by Bureau of Reclamation — U.S. Army Corps of Engineers, public domain. Water levels above come from USGS Water Services and are a separate source. (How this dam was matched to this gauge →)
How Deerfield Reservoir compares nearby
5 of 6 nearby lakes with a current trend are also falling right now.
Nearby lakes
The six nearest published lakes by centroid distance (great-circle) — cross-state neighbors included.
| Lake | State | Level | Distance |
|---|---|---|---|
| Pactola Reservoir | SD | 59.33 ft | 24 km |
| Belle Fourche Reservoir | SD | 58.62 ft | 79 km |
| Lake Francis Case at Chamberlain | SD | 1,351.58 ft | 358 km |
| Wolford Mountain Reservoir | CO | 7,449.63 ft | 486 km |
| White Earth Lake | ND | 2,153.35 ft | 499 km |
| Big Sandy Reservoir | WY | 6,737.68 ft | 499 km |
Frequently asked questions
- What is the current water level of Deerfield Reservoir?
- As of Aug 31, 2026, 2:00 AM (UTC-06:00), the pool elevation was 4.49 ft (datum NGVD29), provisional and subject to revision. See the trend chart above for the recent direction.
- Is Deerfield Reservoir full right now?
- Its managing agency does not publish a %-of-conservation-pool-full figure for this lake, so we show the bare level rather than estimate one.
- Where does this data come from?
- From USGS site 06409500, retrieved Aug 31, 2026, 8:24 AM (UTC+00:00).
More in South Dakota
See every lake tracked in South Dakota, or read the methodology behind these figures.