Rivermatics

USGS Streamgage 06479520

Big Sioux River below Watertown, SD

Big Sioux River below Watertown, SD is USGS streamgage 06479520 in South Dakota, monitoring river discharge in hydrologic subbasin 10170201. It sits on the Big Sioux River, alongside 16 other gauges Rivermatics tracks on the same river. It drains a watershed of about 1,000 square miles. Discharge records at this site go back to 1994. Typical flow runs near 45.6 cfs in July and 173.4 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.

View live conditions & forecast →

Gauge details

State
South Dakota
Drainage area
1,000 sq mi
Gauge elevation
1,703 ft
Subbasin (HUC-8)
10170201
Coordinates
44.84778, -97.04917
USGS site number
06479520
Records begin
1994-10-01 (32 years)
Rivermatics forecast
14-day flow outlook

14-day flow forecast

Based on observations through for Big Sioux River below Watertown, 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
13.7 15.4 17.1
12.7 14.8 17
12.1 14.4 16.7
11.8 14.2 16.7
11.7 14.2 17.2
11.3 14.1 17.4
11.8 14.7 19.7
12.2 15.6 22.6
11.7 15.5 23.1
10.9 14.9 22.3
10.7 14.7 22.3
10.3 14.2 20.9
10.5 14.3 21.7
10.1 13.9 20.5

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 15 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 2.4 7.9 70.7
February 1.6 13.9 184.1
March 7.6 60.7 459.3
April 13.6 173.4 1,878.3
May 15.2 153.6 812.4
June 18.6 121.3 426.9
July 9 45.6 229.5
August 5.6 21.3 171.6
September 5.1 16.6 143.1
October 5.3 16.8 225.4
November 6.8 20.1 237.6
December 4.8 14.3 142.8

All values in cubic feet per second (cfs).

Common questions

When does Big Sioux River below Watertown, SD normally run highest?
April, on the long-term record. The median daily flow that month is about 173.4 cfs, against 7.9 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 below Watertown, SD?
It depends on the month. In January, half of days historically fall near 7.9 cfs, with the middle 80% of days between 2.4 and 70.7 cfs. The month-by-month table on this page gives the full range.
How long has Big Sioux River below Watertown, SD been measured?
Discharge records at USGS site 06479520 begin in 1994, about 32 years, covering roughly 2,824 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 below Watertown, 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 below Watertown, SD?
The gauge sits at 44.84778, -97.04917, in South Dakota, in hydrologic subbasin 10170201, at an elevation of about 1,703 feet, draining roughly 1,000 square miles.
Can I use Big Sioux River below Watertown, 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