A Modular In-Stream Barrier Structure to Limit Upstream Fish Passage

Scientific Disciplines
Biological Sciences - Aquatic
fish screen
fish ladder
Allied Engineering Services Inc.
Mainstream Restoration Inc.
passage impedance
fish barrier
instream barrier
Volume 16, No. 4

A modular in-stream barrier structure to limit upstream 
fish passage

Dale E. Miller,* Mainstream Restoration, Inc., 321 E. Main St., Suite 401, Bozeman, Montana 
59715  dmiller@mainstreamrestoration.com
Paul Sanford, Allied Engineering Services, Inc.,  32 Discovery Drive,  Bozeman, Montana 59715  
Fisheries management objectives that include segregation of native and introduced fish 
species often depend upon installation of a physical in-stream barrier with a long functional 
design life. Fish barrier sites are typically located in remote locations and reflect varied 
topographic and hydrologic conditions. A modular fish barrier, consisting of commercially 
available pre-cast concrete box culverts and slabs, was developed for relatively low-cost, 
permanent installations at multiple locations around the State. The barrier is comprised of 
upright culverts connected to form a weir and abutments and slabs to form splash pads. 
Structural design elements include: weir width; abutment height; and structure stability 
against overturning. Passage impedance design elements include: weir height; preventing pool 

formation at the structure base; and restrictive velocity when leap constraints are exceeded. 
Topographic design elements include: channel-to-weir transitions and grading between the 
abutments and adjacent ground. This barrier has recently been installed on Whites Gulch near 
Canyon Ferry; barriers on Seepay and Magpie Creeks near Dixon and Cottonwood Creek 
near Wolf Creek are in various design phases. This paper presents the basis for the structural, 
passage impedance and topographic design elements as well as design lessons learned from 
the installed barrier.