Rivermatics

USGS Streamgage 06401500

Cheyenne River below Angostura Dam, SD

Cheyenne River below Angostura Dam, SD is USGS streamgage 06401500 in South Dakota, monitoring river discharge in hydrologic subbasin 10120109. It sits on the Cheyenne River, alongside 8 other gauges Rivermatics tracks on the same river. It drains a watershed of about 9,097 square miles. Discharge records at this site go back to 1945. Typical flow runs near 1.9 cfs in July and 1.4 cfs in April, with the higher of the two arriving in July. Rivermatics issues a daily machine-learned flow outlook for this gauge, reaching 14 days ahead.

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Gauge details

State
South Dakota
Drainage area
9,097 sq mi
Gauge elevation
3,085 ft
Subbasin (HUC-8)
10120109
Coordinates
43.345, -103.43667
USGS site number
06401500
Records begin
1945-11-01 (81 years)
Rivermatics forecast
14-day flow outlook

Typical flow by month

Long-term daily discharge percentiles from the USGS record (up to 76 years of data), averaged within each month. These describe the historical normal range — they are not a forecast and not today's reading.

Historical monthly discharge percentiles in cubic feet per second
Month Low p10 Typical p50 High p90 Range
January 1 1.3 76.2
February 0.6 1.4 66.3
March 0.6 1.5 216.7
April 0.6 1.4 156
May 0.7 2 411.5
June 0.8 2.1 624.8
July 0.8 1.9 96.2
August 0.9 1.5 87.2
September 0.8 1.4 34.2
October 0.9 1.4 26.8
November 1 1.4 47
December 0.9 1.3 69.4

All values in cubic feet per second (cfs).

Common questions

When does Cheyenne River below Angostura Dam, SD normally run highest?
June, on the long-term record. The median daily flow that month is about 2.1 cfs, against 1.3 cfs in January, the lowest month. These are historical normals for the date, not a forecast and not today's reading.
What is a normal flow for Cheyenne River below Angostura Dam, SD?
It depends on the month. In January, half of days historically fall near 1.3 cfs, with the middle 80% of days between 1 and 76.2 cfs. The month-by-month table on this page gives the full range.
How long has Cheyenne River below Angostura Dam, SD been measured?
Discharge records at USGS site 06401500 begin in 1945, about 81 years, covering roughly 4,886 days of published daily values. The long record is what makes the monthly percentiles on this page meaningful.
Is there a flow forecast for Cheyenne River below Angostura Dam, SD?
Yes. Rivermatics trains a machine-learned model — a temporal-fusion transformer — on this basin's observed flows, weather, and snowpack, and issues a daily flow outlook reaching 14 days ahead: a median estimate inside a confidence band, not a single number to bet on. Every forecast is scored against days the model never trained on, and that track record is published on the live gauge screen. Open live conditions to see the current outlook.
Where is Cheyenne River below Angostura Dam, SD?
The gauge sits at 43.345, -103.43667, in South Dakota, in hydrologic subbasin 10120109, at an elevation of about 3,085 feet, draining roughly 9,097 square miles.
Can I use Cheyenne River below Angostura Dam, SD data for flood or safety decisions?
No. Rivermatics provides estimates, not guarantees, and the readings and forecasts here may be delayed, inaccurate, or wrong. Do not use them for navigation or for any safety, rescue, or emergency decision. Check the National Weather Service and USGS directly, and use your own judgment.

Upstream and downstream on the Cheyenne River

Every gauge Rivermatics tracks on this river, ordered by drainage area — upstream first. See the Cheyenne River in full.

Other gauges in this subbasin