USGS Streamgage 06485950
Big Sioux River at Sioux City, IA
Big Sioux River at Sioux City, IA is USGS streamgage 06485950 in Iowa, 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 8,430 square miles. Discharge records at this site go back to 2015. Typical flow runs near 2,477.4 cfs in July and 3,299 cfs in April, with the higher of the two arriving in April.
Gauge details
- State
- Iowa
- Drainage area
- 8,430 sq mi
- Gauge elevation
- 1,073 ft
- Subbasin (HUC-8)
- 10170203
- Coordinates
- 42.52444, -96.48019
- USGS site number
- 06485950
- Records begin
- 2015-03-01 (11 years)
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.
| Month | Low p10 | Typical p50 | High p90 | Range |
|---|---|---|---|---|
| January | 221.3 | 953.9 | 3,191 | |
| February | 242.6 | 974.2 | 3,559.6 | |
| March | 559.1 | 1,819.8 | 18,361.3 | |
| April | 948.3 | 3,299 | 17,266.7 | |
| May | 1,186.8 | 4,357.4 | 14,745.2 | |
| June | 1,004.2 | 3,603.3 | 24,690 | |
| July | 617.4 | 2,477.4 | 12,089 | |
| August | 475.1 | 1,348.7 | 5,053.9 | |
| September | 230.4 | 1,259.3 | 14,462.7 | |
| October | 274.2 | 1,006.9 | 9,692.3 | |
| November | 306.7 | 1,336.7 | 6,925.7 | |
| December | 293.9 | 1,344.8 | 3,835.2 |
All values in cubic feet per second (cfs).
Common questions
- When does Big Sioux River at Sioux City, IA normally run highest?
- May, on the long-term record. The median daily flow that month is about 4,357.4 cfs, against 953.9 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 at Sioux City, IA?
- It depends on the month. In January, half of days historically fall near 953.9 cfs, with the middle 80% of days between 221.3 and 3,191 cfs. The month-by-month table on this page gives the full range.
- How long has Big Sioux River at Sioux City, IA been measured?
- Discharge records at USGS site 06485950 begin in 2015, about 11 years, covering roughly 4,090 days of published daily values. The long record is what makes the monthly percentiles on this page meaningful.
- Where is Big Sioux River at Sioux City, IA?
- The gauge sits at 42.52444, -96.48019, in Iowa, in hydrologic subbasin 10170203, at an elevation of about 1,073 feet, draining roughly 8,430 square miles.
- Can I use Big Sioux River at Sioux City, IA 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.
- Big Sioux River near Florence, SD 68 sq mi
- Big Sioux River near Watertown, SD 525 sq mi
- Big Sioux River at Lake Kampeska near Watertown, SD 539 sq mi
- Big Sioux River at Watertown, SD 806 sq mi
- Big Sioux River at Broadway at Watertown, SD 870 sq mi
- Big Sioux River below Watertown, SD 1,000 sq mi
- Big Sioux River near Castlewood, SD 1,096 sq mi
- Big Sioux River near Bruce, SD 2,396 sq mi
- Big Sioux River near Brookings, SD 3,338 sq mi
- Big Sioux River near Dell Rapids, SD 3,927 sq mi
- Big Sioux River below Diversion at Sioux Falls, SD 3,999 sq mi
- Big Sioux River at Sioux Falls, SD 4,642 sq mi
- Big Sioux River at North Cliff Ave at Sioux Falls, SD 4,662 sq mi
- Big Sioux River near Hawarden, IA 7,566 sq mi
- Big Sioux River at Akron, IA 7,879 sq mi
- Big Sioux River near Jefferson, SD 8,400 sq mi
- Big Sioux River at Sioux City, IA this page