Castle Rock
Flowage Map
This Castle Rock Flowage area base map,
while representing the best information currently available to the
WRPCO, should not be relied upon
entirely by those using flowage waters and land for fishing, boating,
swimming, hiking and other recreational activities. Individuals must
use extreme caution because of the size, complexity, and constantly
changing conditions of Castle Rock Flowage. The information on the
map is a composite of United States Coast and Geodetic Survey
(USC&GS) data and underwater contour data provided by the
University of Wisconsin-Stevens Point (UW-SP) and the Wisconsin
Department of Natural Resources (DNR).
Persons desiring more information or wishing to report particular
incidents or conditions observed on Castle Rock Flowage may contact a
WRPCO representative at 1-800-53-WATCH.
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Origins
The Castle Rock Flowage consists of 16,640 acres and is the fourth
largest inland body of water in Wisconsin. It was built in the late
1940s for hydroelectric generation and flood control. The flowage is
on Wisconsin's Central plain or Central Sand, the ancient bed of
Glacial Lake Wisconsin that was a prehistoric one-million-acre body
of water.
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Wisconsin River
The Wisconsin River is the hardest working river in the nation.
From its headwaters on the Wisconsin-Michigan border in Lac Vieux
Desert, it falls more than 1,000 feet on its 500-mile journey through
the state, before emptying into the Mississippi River at Prairie du
Chien.
Since the Ice Age, the mighty river has scoured gorges and cut great
rapids and waterfalls, whose roar has been replaced by the hum of
turbines and waterwheels at 26 hydroelectric dams. The energy generated
each year would supply the electrical needs of every home in Madison
for a year.
The Wisconsin, long notorious for devastating floods, is now
partially controlled by 21 reservoirs (flowages) on the river. Many
reservoirs are lowered prior to spring runoff in anticipation of high
water when spring breakup begins.
The Castle Rock Dam and the Petenwell Dam (its sister upriver) are
unique, because they are built on sand and were the first such
projects undertaken in the United States. The concrete dams are
classified as "floating-type construction" with imbedded cutoff walls
that penetrate deep into the glacial sands, permanently anchoring them.
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Conditions Vary Greatly
Prior to construction of the Castle Rock Dam, the lake bed was
farmland, prairie, and forested knolls and was bisected by the
meandering Wisconsin River. As with most flowages, Castle Rock is
relatively shallow and quickly becomes turbulent on windy days.
Bottom conditions and depths vary considerably. Boaters are urged to
become familiar with this map before any activity on the flowage.
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Open to the Public
Since flowage establishment, most of WRPCO's surrounding land has
been open to the public for hunting, fishing, hiking, nature
observation, skiing, and other recreational activities. Also, several
40-acre blocks have been dedicated as school forests. The flowage's
namesake, Castle Rock, is downriver from the dam and is a local
geological landmark.
The power company has opened selected portions of its east dike to
public use for fishing, hiking, and nature observation, on a trial
basis. Hunting and trapping are not permitted. The area offers good
views of the flowage and some bank fishing. Located in Adams County in
the Town of Quincy, this area stretches from Adams County Castle Rock
Park south to the public access point near the Castle Rock Dam and
Powerhouse.
Parking for the east dike is available at the Adams County Castle
Rock Park or Castle Rock Dam areas. Absolutely no vehicular traffic
is permitted on the dike system. Campfires and overnight camping are
also prohibited.
Persons who have special interests in visiting closed portions of
the dike system and related wildlife areas should contact WRPCO for
more information.
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Wildlife Protection
The power company has cooperated with the Wisconsin DNR in
establishing a trout fishery in portions of the Castle Rock ditch
system and in erection of osprey nesting platforms and wood duck
nests. The backwaters and sloughs immediately below Petenwell Dam,
a favorite winter refuge for bald eagles, have been designated as a
wildlife refuge by the power company. In cooperation with the DNR,
the Federal Energy Regulatory Commission (FERC), and UW-SP, WRPCO
has completed a management plan for this area. A walking trail
through portions of the area is open to the public from May 1 to
October 1.
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Forest Management
Professional foresters manage forest land surrounding the Castle
Rock Flowage for sustained timber production. More than 2,000 acres
of marginal farmland have been forested, and over two million trees
have been planted.
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Good Fishing Opportunities
The flowage offers some of the Wisconsin River's best fishing.
Locally known fishing "hot spots" include the railroad bridge
crossing, the area near the Buckhorn Bridge, and the east bank below
the dam. These areas provide abundant underwater structure and harbor
good concentrations of fish.
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Water Level Fluctuate
The primary purpose of the Castle Rock Flowage is to store water that
creates a water head (height) to produce electricity as it passes (drops)
through the hydroturbines at the dam.
Flood control is another purpose. Flood control is accomplished by
an annual drawdown that begins in February. The drawdown is governed by
the amount of water in the snowcover in the state's northern section.
The flowage is refilled as the snow melts, normally beginning in late
March. By May 1, the flowage must be full and at normal summer levels.
Between June 15 and February 1, the headwater elevation fluctuation is
limited to a maximum of one foot.
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Federal License
The Castle Rock Dam is operated by the WRPCO under licenses from the
FERC. The federal license provides control over flowage operations and
requires that the company outline an overall land use and recreation
plan that provides for full public utilization of the waters and land.
The current license expires on December 7, 2031.
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A flashing beacon is a warning that a flood gate is open. All
boaters should always stay at least 500 feet upstream from the dam. For
added safety, a restraining cable with orange floats and regulatory
warning buoys have been installed, as shown on the above drawing. The
cable is installed after spring breakup and is removed in late October.
This cable spans the upstream powerhouse intake area and the gate section.
Anchoring to the cable, except for emergencies, is prohibited.
Similar cable and floats have been installed just downstream from the
turbine discharge area. These hydro units are remote controlled and can
come on without warning. Safe boating procedures are a must, especially
near dams!
Because Castle Rock is a flowage, it naturally becomes more shallow
further upriver. The waters also conceal shallows in other unexpected
areas, even long distances from shore. The northern portions of the
Wisconsin River and Yellow River areas of the flowage, as well as the
west shore south of the railroad bridge, also have shallow, stumpy areas.
Therefore, proceed with caution.
Boaters may occasionally encounter floating debris from upriver or
which broke loose from the shoreline. If the debris poses a water hazard,
please mark it and notify a representative of the power company at
1-800-53-WATCH.
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