Big Sioux River near Egan

Highest listed crest 1,524.20 ftFlood stage 1,516.5 ft7 crests since 2018

The Big Sioux River near Egan crested at major flood stage 2 times among the 7 crests the National Weather Service lists from 2018 to 2025. The highest, 1,524.20 ft on September 12, 2019, was major flooding, 7.70 feet above flood stage. 13 other gauges on the Big Sioux River crested above flood stage within a week of it, 8 at their own highest listed crest.

The gauge

Highest listed crest: 1,524.20 ft; September 12, 2019
Flood stage: 1,516.5 ft; Major flooding from 1,521.0 ft
Crests at major: 2; 42nd of 155 gauges in South Dakota
Most recent flood crest: June 23, 2024; 1,519.36 ft, moderate flooding
Location: Moody County; South Dakota
Identifiers: NWS EGAS2; No USGS station

Flood stages

The thresholds the National Weather Service uses for this gauge today, and how many listed crests reached each.

Flood categories, Big Sioux River near Egan

Action stage	1,515.0	1	Jul 3, 2025	The level at which the NWS or its partners begin to take action
Flood stage (minor)	1,516.5	2	Apr 15, 2023	Minimal or no property damage, but possibly some public threat
Moderate flood stage	1,519.0	2	Jun 23, 2024	Some inundation of structures and roads near the stream
Major flood stage	1,521.0	2	Sep 12, 2019	Extensive inundation of structures and roads

Every listed crest

7 crests from 2018 to 2025. Filled: at or above flood stage. Hover a crest for its date and stage.

Crests at or above flood stage, by decade

These are the crests the local National Weather Service office lists for the gauge: the highest on record and recent crests. Lesser floods between them may be missing, so counts by decade are a floor.
Categories use today's flood stages. Levees, dams and channel changes since a crest can make old and new stages not directly comparable.

Highest crests

Highest listed crests, Big Sioux River near Egan

1	Sep 12, 2019	1,524.20	+7.70	Major	—
2	Mar 23, 2019	1,522.48	+5.98	Major	—
3	Apr 26, 2018	1,520.30	+3.80	Moderate	—
4	Jun 23, 2024	1,519.36	+2.86	Moderate	—
5	Mar 13, 2020	1,517.64	+1.14	Minor	—
6	Apr 15, 2023	1,517.09	+0.59	Minor	—
7	Jul 3, 2025	1,515.46	−1.04	Action	—

The worst floods along the Big Sioux River

For this gauge's highest crests, the other gauges on the Big Sioux River that crested above flood stage within a week.

September 12, 2019: 1,524.20 ft here, major flooding

FlandreauSD · Sep 13, 2019 · 1,545.29 ft · Major · its highest
TrentSD · Sep 13, 2019 · 1,501.42 ft · Major · its highest
Dell RapidsSD · Sep 13, 2019 · 1,490.00 ft · Major · its highest
BrandonSD · Sep 14, 2019 · 1,313.53 ft · Major · its highest
CantonSD · Sep 13, 2019 · 1,245.88 ft · Major
RichlandIA · Sep 17, 2019 · 1,123.51 ft · Major
HawardenSD · Sep 15, 2019 · 32.42 ft · Major
Sioux Falls I-90SD · Sep 14, 2019 · 18.91 ft · Major · its highest
Dell RapidsSD · Sep 13, 2019 · 16.70 ft · Major · its highest
FairviewSD · Sep 14, 2019 · 1,213.14 ft · Moderate · its highest

March 23, 2019: 1,522.48 ft here, major flooding

TrentSD · Mar 24, 2019 · 1,500.00 ft · Major
Dell RapidsSD · Mar 24, 2019 · 1,487.53 ft · Major
RichlandIA · Mar 16, 2019 · 1,124.50 ft · Major
JeffersonIA · Mar 17, 2019 · 40.42 ft · Major
AkronIA · Mar 16, 2019 · 23.94 ft · Major
Dell RapidsSD · Mar 24, 2019 · 15.69 ft · Major
WatertownSD · Mar 28, 2019 · 12.31 ft · Major
EstellineSD · Mar 28, 2019 · 1,646.90 ft · Moderate
FlandreauSD · Mar 23, 2019 · 1,543.53 ft · Moderate
Sioux Falls N. Cliff AvenueSD · Mar 26, 2019 · 22.06 ft · Moderate

April 26, 2018: 1,520.30 ft here, moderate flooding

EstellineSD · Apr 23, 2018 · 1,645.90 ft · Moderate
FlandreauSD · Apr 25, 2018 · 1,542.40 ft · Moderate
TrentSD · Apr 26, 2018 · 1,498.00 ft · Moderate
Sioux Falls I-90SD · Apr 28, 2018 · 16.30 ft · Moderate
Dell RapidsSD · Apr 27, 2018 · 14.20 ft · Moderate
BrookingsSD · Apr 24, 2018 · 12.30 ft · Moderate
Watertown Broadway AvenueSD · Apr 23, 2018 · 11.30 ft · Moderate
BruceSD · Apr 23, 2018 · 10.20 ft · Moderate
BrandonSD · Apr 28, 2018 · 1,307.40 ft · Minor
Sioux Falls N. Cliff AvenueSD · Apr 28, 2018 · 16.90 ft · Minor

Gauges on the Big Sioux River

Flood gauges sharing the river's name, linked within 80 miles of one another.

Flood gauges on the Big Sioux River

Canton	SD	1,235.0	1,248.35 ft, Jun 22, 2024	3
Dell Rapids	SD	1,481.0	1,490.00 ft, Sep 13, 2019	2
Flandreau	SD	1,540.0	1,545.29 ft, Sep 13, 2019	1
Hawarden	SD	20.5	39.92 ft, Jun 22, 2024	4
Akron	IA	16.0	27.35 ft, Jun 22, 2024	24
Fairview	SD	1,202.0	1,213.14 ft, Sep 14, 2019	0
Lake Kampeska	SD	21.0	22.40 ft, Mar 15, 2010	0
Lake Poinsett Inlet/Outlet	SD	1,654.0	1,657.60 ft, Apr 5, 2011	2
Sioux City	SD	32.0	44.90 ft, Jun 23, 2024	1
Sioux Falls I-90	SD	12.0	18.91 ft, Sep 14, 2019	1
Sioux Falls N. Cliff Avenue	SD	16.0	26.08 ft, Sep 14, 2019	0
Sioux Falls Western Avenue	SD	8.0	16.90 ft, Mar 14, 2019	4
Trent	SD	1,495.0	1,501.42 ft, Sep 13, 2019	2
Watertown Broadway Avenue	SD	10.5	13.67 ft, Apr 6, 1997	1
Watertown Sioux Conifer Road	SD	9.0	11.18 ft, Apr 13, 2023	0
Watertown	SD	11.0	13.13 ft, Apr 2, 1997	5
Brandon	SD	1,304.0	1,313.53 ft, Sep 14, 2019	2
Brookings	SD	9.0	14.77 ft, Apr 9, 1969	0
Bruce	SD	8.0	12.16 ft, Mar 28, 2011	0
Castlewood	SD	9.0	13.19 ft, Apr 7, 1997	0
Dell Rapids	SD	12.0	16.70 ft, Sep 13, 2019	10
Egan this gauge	SD	1,516.5	1,524.20 ft, Sep 12, 2019	2
Estelline	SD	1,644.0	1,647.03 ft, Jun 30, 2025	0
Florence	SD	8.0	9.70 ft, Apr 13, 2023	6
Jefferson	IA	31.0	44.50 ft, Jun 24, 2024	2
Richland	IA	1,117.0	1,128.70 ft, Jun 23, 2024	5
Watertown	SD	10.0	12.33 ft, Apr 7, 2001	2

Other gauges in Moody County

Flood gauges in Moody County

Flandreau	1,540.0	1,545.29 ft, Sep 13, 2019	1
Trent	1,495.0	1,501.42 ft, Sep 13, 2019	2
Brookings	9.0	14.77 ft, Apr 9, 1969	0
Flandreau	9.0	14.00 ft, Sep 12, 2019	0
Chester	7.0	7.45 ft, Jul 10, 2011	0

Moody County: every hazard · River floods across the country · South Dakota

NOAA National Water Prediction Service, gauge EGAS2, retrieved October 30, 2026. Stages in feet on the gauge's own datum, not elevation. Crests are as the National Weather Service lists them; preliminary values may be revised.