River stage
Lake Koshkonong, Rock River
- River level
- 6.78 ft
- Status
- Below flood stage
- 7-day change
- -0.22 ft
- Recent high
- 7.06 ft
- Recent low
- 6.27 ft
Last reported 2026-10-13 | NWS NVLW3
- 30-day change
- +0.04 ft
- Average
- 6.73 ft
- Readings
- 122
- Data span
- 122 days
- Record crest
- 15.13 ft
In brief
The Rock River at Lake Koshkonong, WI read 6.78 ft on Oct 13, 2026, 2.22 ft below action stage. That is 0.04 ft higher than 30 days earlier.
Source: National Weather Service gauge NVLW3
River level timeline
Stage threshold profile
Highest crests on record
| Rank | Crest | Date |
|---|---|---|
| 1 | 15.13 ft | 2008-06-21 |
| 2 | 12.35 ft | 2013-04-22 |
| 3 | 12.23 ft | 1993-04-25 |
| 4 | 11.65 ft | 2008-04-18 |
| 5 | 11.62 ft | 2018-09-12 |
| 6 | 11.50 ft | 2019-03-25 |
| 7 | 11.49 ft | 2004-06-05 |
| 8 | 11.42 ft | 2026-04-24 |
Flood crests recorded at this gauge by the National Weather Service.
What happens at each level
- 9.00 ft
Water spreads into low lying areas along Lake Koshkonong. Water into yards along Blackhawk Island.
- 9.50 ft
Water is into low lying areas along Lake Koshkonong. Water approaches homes along Blackhawk Island.
- 10.00 ft
Floodwaters affect homes and boat docks in the Blackhawk Island area of Lake Koshkonong on the north side of the lake. Floodwaters spread over low spots on Blackhawk Island Road in the area where the Rock River enters the lake.
- 10.50 ft
Floodwaters reach Oxbow Bend Road in the area of the gage on the east side of the lake. Flooded roads: The end of Road 9, end of E Road 8 St, end of E Road 7, Lakeview Dr, Charley Bluff Rd north of Royce Dallman Park, parts of Lamp Rd, Willow Rd, parts of Blackhawk Island Rd. Water surrounds some structures on Lamp Rd and towards end of Blackhawk Island Rd. Low lying areas of Lakeland Campground flood. Altpeter County Park floods. Water into yards along High Ridge Rd.
- 11.00 ft
In the Town of Lake Koshkonong, floodwaters affect Vets Lane, Blackhawk Island Road, and Oxbow Bend Road. There is widespread flooding of roads and docks in the Town of Koshkonong and Town of Sumner including Vets Lane, Blackhawk Island Road and Oxbow Bend Road.
- 11.30 ft
There is knee-deep water over Blackhawk Island Road. Lamp Road on west side of river also becomes flooded. Lake Koshkonong merges with Mud Lake to the east of Lake Koshkonong.
- 12.00 ft
There is widespread flooding of lakeside homes and roads in the Lake Koshkonong area including Vets Lane, Blackhawk Island Road and Oxbow Bend Road.
- 13.00 ft
There is widespread flooding of lakeside homes and roads in the Lake Koshkonong area including Vets Lane, Blackhawk Island Road and Oxbow Bend Road.
- 14.00 ft
There is widespread flooding of lakeside homes and roads in the Lake Koshkonong area including Vets Lane, Blackhawk Island Road and Oxbow Bend Road.
Written by the local National Weather Service forecast office for this exact gauge.
Frequently asked questions
Is the Rock River flooding at Lake Koshkonong?
No. The Rock River at Lake Koshkonong is at 6.78 ft, 2.22 ft below action stage.
What is the flood stage at Lake Koshkonong?
The National Weather Service sets action stage 9 ft, minor flooding 10 ft, moderate flooding 11 ft and major flooding 11.5 ft.
What is the highest the Rock River has been at Lake Koshkonong?
The highest crest on record is 15.13 ft, on 2008-06-21.
Is the Rock River high or low right now at Lake Koshkonong?
At 6.78 ft it is higher than 69% of readings over the last 122 days.
Stage and flood information from the NOAA National Weather Service (gauge NVLW3); daily history from the U.S. Geological Survey (site 05427235). Last reading 2026-10-13. For flood safety decisions always follow official National Weather Service warnings.