The Eau Galle River has its origins in St.Croix County
and flows 51 miles to its confluence with the Chippewa River in Pepin County.
Early settlers found the Eau Galle River to be an exceptional Trout Stream
supporting large native Brook Trout. As with many area streams, changing land
use degraded water quality and habitat leaving the native Brook Trout only in
the far reaches of the river's headwater streams. The introduction of the Brown
Trout, which tolerates warmer water than the Brook, allowed for an excellent
fishery. In 1966, an earthen flood control dam was constructed to protect the
village of Spring Valley.
The dam forms a 150-acre impoundment, which is located 50 miles east of the
Twin Cities and 40 miles southwest of Eau Claire. The river is a relatively
large trout stream for Western Wisconsin holding primarily Brown Trout from
Spring Valley to Elmwood, and Brook Trout downstream from Cady Creek. This trout
water is Class II trout water that means fish must be stocked to provide a
viable fishery. Below Spring Valley, the stream picks up many smaller brook
trout waters including Cady, Mines, and Burkhardt.
During the 1960s the base stream flow of the Eau Galle was 12 cfs (cubic ft.
second) with a bottom draw setting of about 10 cfs or 83%. By 1998 the base flow
had increased to 22 cfs with the percent of bottom draw unchanged. This resulted
in the majority (55%) of water flowing off the top of the reservoir creating
downstream water temperatures too warm in summer and too cold in the winter for
trout to survive. In addition, a large weir downstream of the dam retained water
in a large shallow channel allowing the water to warm further. Downstream stream
habitat is in poor shape with high eroding banks.
Documented trout numbers throughout the river below Spring Valley were low
(50-350 trout /mile). In contrast, area streams such as the Rush, Kinnickinnic,
Plum and Cady Creek have densities of 3,000 to 8,000 trout/mile. Additionally
coldwater Index of Biological Integrity (IBI) scores for the Eau Galle were
marginal. There is little or no reproduction and survival of stocked trout is
poor. Clearly, the temperature of the dam's discharge was severely degrading the
Eau Galle's trout fishery. Trout survive in a narrower temperature range than
other species.
A "Coldwater Stream" has a mean maximum daily water temperature < 72 F with
optimal summer water temperatures for growth and survival of trout between 53.6
-66.2 F. In addition, optimal winter water temperatures for egg and fry
development must be between 37 and 55 F. Water temperatures > 81 F is lethal to
trout.
In 1998, the Wisconsin Department of Natural Resources explored an
environmental restoration project below the dam to improve trout habitat and
restoration on the Eau Galle River. In 1999, the WI DNR gathered data to confirm
that thermal problems were impacting the river.
Fish Manager Marty Engel established the following trout management goals and
objectives for the proposed project.
Eau Galle River Restoration Project
Goals and Objectives
Eliminate or reduce water temperature
problems that create conditions lethal to trout.
Reduce number of daily water temperatures
> 72 F.
Provide mean summer water temperatures
that in the optimal range for trout.
Provide winter water temperatures that
are optimal for egg and fry development.
Increase natural reproduction of brown
trout and/or substantially improve stock survival.
Improve downstream habitat.
Improve trout populations downstream to
moderate densities (1500 -3500 trout/mile).
The DNR consulted with the Army Corps of Engineers, City of Spring Valley,
Eau Galle-Rush River Sportsman, and Trout Unlimited during the winter of
1999-2000. These discussions led to and implementation plan that incorporated
the following points:
Implementation Plan
Increase bottom draw from @ 10 cfs to >
18 cfs to improve water temperatures (Summer 2000).
Remove and replace weir / restore stream
channel and habitat (Fall 2003).
Improve stream habitat through town (Fall
2004).
Improve habitat downstream from Spring
Valley (future).
Over the summer of 2000 the Army Corps of Engineers, in an experimental
release, initiated the sub-surface hypo-limnetic release to maximize sub-surface
withdrawal to promote a more optimal thermal regime in the river. During this
time, the DNR repeated the same thermal monitoring sampling from 1999.