How high is the Big Sioux River Near Jefferson, SD right now?

The Big Sioux River Near Jefferson, SD is currently flowing at 1,830 cubic feet per second with a gage height of 11.15 feet, based on the most recent USGS instantaneous reading.

Is the flow on the Big Sioux River Near Jefferson, SD normal for this time of year?

Current flow is classified as normal for October 28. Today's discharge is at the 60th percentile compared to the long-term historical record at this gauge.

Is the Big Sioux River Near Jefferson, SD at flood stage?

No — the gage height is 19.85 feet below the NWS flood-stage threshold of 31.0 feet.

What is the historical median flow for the Big Sioux River Near Jefferson, SD on October 28?

The long-term median discharge for this date is 1,030 cfs based on USGS daily statistics. The 10th–95th percentile range historically is 280 to unavailable cfs.

Where is the Big Sioux River Near Jefferson, SD stream gauge located?

The Big Sioux River Near Jefferson, SD stream gauge is operated by the USGS in Union County, SD on the Big Sioux River. USGS site number 06485910 (coordinates 42.6264, -96.5156).

Big Sioux River Near Jefferson, SD

USGS Site No: 06485910 • Big Sioux River • Union County, SD

Big Sioux River Near Jefferson, SD on the Big Sioux River is currently at 1,830 cfs (Normal — 60th percentile for this date) . Gage height: 11.15 ft.

Reading from 4 months ago

↑ Upstream on Big Sioux River

Big Sioux River Near Hawarden, IA

1,830

CFS Discharge

11.15

Gage Height (ft)

Normal

Flow Condition

Normal

Flood Status

Historical Percentile Comparison

Today's discharge compared to the long-term record for October 28 at this station. Percentile rank shows what fraction of historical years had lower flow on this date.

Percentile	Label	CFS Threshold	Today's Flow
10th	Very Low threshold	280
25th	Low threshold	535
50th (Median)	Normal (median)	1,030
75th	High threshold	2,990	Today: 1,830 cfs
95th	Very High threshold	0

30-Day Hydrograph

Recent discharge plotted against the historical 10th–95th percentile envelope for the same calendar days. Source: USGS daily values + long-term statistics.

10th–95th historical Day-of-year median Recent discharge

30-Day Flow History

Date	Discharge (CFS)	Gage Ht (ft)
May 28, 2026	2,140	—
May 27, 2026	2,010	—
May 26, 2026	1,600	—
May 25, 2026	1,490	—
May 24, 2026	1,440	—
May 23, 2026	1,490	—
May 22, 2026	1,490	—
May 21, 2026	1,570	—
May 20, 2026	1,630	—
May 19, 2026	1,630	—
May 18, 2026	1,470	—
May 17, 2026	2,120	—
May 16, 2026	1,030	—
May 15, 2026	1,130	—
Apr 20, 2026	1,110	—
Apr 19, 2026	1,120	—
Apr 18, 2026	1,110	—
Apr 17, 2026	1,160	—
Apr 16, 2026	1,180	—
Apr 15, 2026	1,180	—
Apr 14, 2026	1,200	—
Apr 13, 2026	1,220	—
Apr 12, 2026	1,240	—
Apr 11, 2026	1,250	—
Apr 10, 2026	1,260	—
Apr 9, 2026	1,270	—
Apr 8, 2026	1,270	—
Apr 7, 2026	1,240	—
Apr 6, 2026	1,170	—
Apr 5, 2026	1,190	—

Station Information

USGS Site No: 06485910
State: SD
County: Union County
Coordinates: 42.6264, -96.5156
Drainage Area: 8,400 mi²
Datum (ft): 1,069.9
HUC Code: 101702032507

View on USGS NWIS →

Flood Stage Thresholds

Action Stage: 28.0 ft
Flood Stage: 31.0 ft
Moderate Flood: 35.0 ft
Major Flood: 40.0 ft

Currently 19.85 ft below flood stage.

Recent Extremes

Max discharge: 4,580 cfs

Jul 8, 2025
Min discharge: 702 cfs

May 21, 2025
Days at flood stage: 0

Computed from the local daily-values archive.

Nearby Gauges

Big Sioux River at Sioux City, IA
7.3 mi · 0 cfs

Unknown
Perry Creek at 38th Street at Sioux City, IA
8.3 mi · 24 cfs

Very High
Perry Creek Near Millnerville, IA
8.7 mi · 3 cfs

Normal
Floyd River at James, IA
10.9 mi · 861 cfs

Very High
Missouri River at Sioux City, IA
11.0 mi · 28,400 cfs

Normal