Rivermatics

USGS Streamgage 06485910

Big Sioux River near Jefferson, SD

Big Sioux River near Jefferson, SD is USGS streamgage 06485910 in South Dakota, monitoring river discharge in hydrologic subbasin 10170203. It sits on the Big Sioux River, alongside 16 other gauges Rivermatics tracks on the same river. It drains a watershed of about 8,400 square miles. Discharge records at this site go back to 2015. Typical flow runs near 2,575.5 cfs in July and 3,052.7 cfs in April, with the higher of the two arriving in April. 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
8,400 sq mi
Gauge elevation
1,079 ft
Subbasin (HUC-8)
10170203
Coordinates
42.62639, -96.51528
USGS site number
06485910
Records begin
2015-03-01 (11 years)
Rivermatics forecast
14-day flow outlook

14-day flow forecast

Based on observations through for Big Sioux River near Jefferson, SD. Each day carries a median estimate and the band the model expects the flow to fall within — not a single number to plan against. Forecasts are re-issued daily; see the live screen for the current outlook.

Forecast daily mean discharge in cubic feet per second, by date
Date Low p10 Expected p50 High p90 Range
968 1,144 1,403
835 1,051 1,418
765 1,008 1,557
696 983 1,682
652 945 1,663
601 897 1,650
629 963 2,034
680 1,285 3,832
768 2,124 6,797
806 2,237 6,662
811 2,083 5,763
793 1,914 4,995
714 1,677 4,577
662 1,515 4,189

All values in cubic feet per second (cfs). Estimates only — do not use them for navigation or for any safety, rescue, or emergency decision.

Typical flow by month

Long-term daily discharge percentiles from the USGS record (up to 11 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 220.2 769.8 2,893.5
February 285.2 771.5 3,258.6
March 529.4 1,768 17,388.1
April 895 3,052.7 16,023.3
May 967.5 4,250.3 14,103.2
June 935.3 3,485.3 22,710.3
July 624.7 2,575.5 11,471.9
August 455.8 1,379.7 5,230.3
September 248.7 1,137.9 13,298
October 269.2 902.2 9,317.4
November 267.6 1,151.5 5,246.7
December 289.2 1,088.8 3,309.4

All values in cubic feet per second (cfs).

Common questions

When does Big Sioux River near Jefferson, SD normally run highest?
May, on the long-term record. The median daily flow that month is about 4,250.3 cfs, against 769.8 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 Big Sioux River near Jefferson, SD?
It depends on the month. In January, half of days historically fall near 769.8 cfs, with the middle 80% of days between 220.2 and 2,893.5 cfs. The month-by-month table on this page gives the full range.
How long has Big Sioux River near Jefferson, SD been measured?
Discharge records at USGS site 06485910 begin in 2015, about 11 years, covering roughly 4,067 days of published daily values. The long record is what makes the monthly percentiles on this page meaningful.
Is there a flow forecast for Big Sioux River near Jefferson, 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 Big Sioux River near Jefferson, SD?
The gauge sits at 42.62639, -96.51528, in South Dakota, in hydrologic subbasin 10170203, at an elevation of about 1,079 feet, draining roughly 8,400 square miles.
Can I use Big Sioux River near Jefferson, 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 Big Sioux River

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

Other gauges in this subbasin