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Round Lake Property Owners Association
HomeRound Lake Water Surface Elevation

Carlson Road/Round Lake Dam Update

The long-debated Carlson Road/Round Lake Dam replacement project was completed in early December of 2019. The original timber structure was removed and replaced with a precast concrete box culvert. A minimum flow was maintained through the construction zone during the approximately 1-week construction project. Final cleanup and seeding will be done this spring.

RLPOA had been told on several occasions that the new box culvert would be set approximately 6-inches below the existing timber structure. That measurement changed during the course of the debate to a court ordered elevation of 1343.60 (existing structure was at 1343.91, so 3.7 inches lower) or 0.5 feet below the bed of the channel, whichever is lower in elevation (Wisconsin DNR Permit IP-NO-2013-58-02643).

During construction, the contractor was directed to set the culvert at 0.5 feet below the bed of the channel which ended up being 1342.62. The new culvert was set 1.29 feet (15.5 inches) below the elevation of the original timber structure.

It is somewhat difficult to predict how this will ultimately affect the water level in Round and Little Round lakes. Given that the new culvert is much lower than the original structure, the opportunity for more outflow certainly exists. However, this is a rather complex hydraulic problem. Depending on the level of the lake, precipitation, and condition of the channel downstream of the culvert, the physical barrier that controls the water level may change throughout the year.

RLPOA is concerned about the fact the new culvert was installed significantly lower than previously discussed. We will be monitoring precipitation and lake level again this summer, as we have done for the past several years. That data will be available on the website.

Red outline is the original timber structure. Gray outline is the new concrete box culvert. The structures are drawn to scale at the correct elevations. The horizontal lines at the top represent the elevation of Carlson Road.

Carlson Road/Round Lake Dam Project

To satisfy those curious about construction progress we have created a photo log of the construction which anyone can access periodically for updates.

Construction Photo Log

Here is a video clip of the roadway section of the old dam being removed by the two excavators onsite. 


Precip - Daily Precipitation
Obs - Periodic Staff Gauge Observation
2018 - Periodic Staff Gauge Observations
HOBO - Electronic Gauge Reading (adjusted)

(Note precipitation data is only available 10 days to last HOBO reading)

181231Water Level 


The water surface elevation data shown above is based on direct staff gauge readings (Actual), electronic gage readings (Gauge) and precipitation records (Precip) from the Hayward airport recording station.

The left axis (elevation) is mean sea level (NAVD 88). Note that 0.1 feet equals 1.2 inches. The right axis (precipitation) is in inches.

The actual readings are taken periodically at the staff gauge on the County Highway B bridge. RLPOA used a surveyor to establish the benchmark elevation for this staff gauge.

The gauge readings are take every 5 minutes, 24 hours a day, 7 days a week, excepting any downtime from technical/mechanical failures. The gauge is a pressure transducer that measures the “weight” of the water column above the sensor. More weight means higher water level; less weight means lower water level. The daily reading is obtained by average the 2 hours of readings between 11:00 a.m. and 1:00 p.m. We used the actual readings and gauge readings to develop a calibration curve using linear regression—this lets us convert the gauge reading into an estimated true lake level. We are continuing to work with the vendor to better calibrate this gauge.

The precipitation data comes from NOAA records for the Hayward airport.

Osprey Creek Under County Highway NN

Summer 2019 CTH NN Culverts