CONCRETE DIVERSION BLOCKS
Concrete Blocks
Available Through Cost Share Program
The Gallatin Conservation District currently has several of the concrete
irrigation blocks available at a 50% cost share rate. The diversion blocks are
the standard size of 6’ x 2’ made by Big Sky Ready Mix
The total cost per block was $162.50 and
is available for the 50% cost share price of $81.25 per block (includes shipping from Big Sky Ready Mix in
To purchase these concrete blocks contact:
Gallatin Conservation District
Phone:
(406) 522-4011
Fax:
(406) 585-1272
E-mail:
marcie.murnion@mt.nacdnet.net
.
There will be personnel available to
assist in evaluating locations for the suitability of these blocks if needed.
Informative
Article
A new irrigation diversion system using
portable concrete blocks has been developed by the Department of Natural
Resources and Conservation (DNRC). A 223 Grant acquired by the Gallatin County
Conservation District provided money to construct two steel concrete forms
capable of building a wide variety of block sizes and purchased 18 concrete
blocks to build a diversion on the
The concrete
blocks are relatively inexpensive, very durable, and can be loaded onto the
streambed rapidly. A chain is hooked onto exposed rebar at the top of the
blocks for lifting. The blocks are set directly on the stream bed and have
sufficient weight to provide a stable dam. The blocks are set on the streambed,
after spring runoff, to allow the stream to freely flush gravel bed-load and
debris through the diversion site. The concrete block diversion is typically
built as a wing dam and excess flows go around the upstream end of the
diversion rather than overtopping the blocks. The blocks are removed at the end
of the irrigation season and stored on the stream-bank. Vertical holes can be
installed in the blocks to provide a method to add flashboards on the top of
the blocks if needed.
The concrete block diversion was designed
to provide an environmentally friendly alternative to traditional diversion
methods of using permanent dams constructed with large rock and temporary dams
constructed with river gravels. The only permit required for this diversion
would be a 310 annual or 10 year permit from the local Conservation District.
Technical assistance is available from DNRC for design and installation of new
concrete block diversions.
Advantages of Concrete Block Diversion
Dams
- easy and fast to install and remove
- local farm equipment can be used to install the block diversion
- an inexpensive alternative to permanent rock and concrete diversion dams
- concrete blocks last many years
- promotes stream channel stability because the blocks are installed after
channel forming flows occur in the spring
- reduces long term maintenance of the diversion site
- minimizes safety hazards and interference to recreational floaters
- allows fish passage around the block diversion structure
- if the stream moves, the blocks can be moved to a new stream position
- blocks are typically used to build wing dams rather than cross channel dams
Disadvantages
- an area on the stream bank adjacent to the diversion is required to store the
blocks
- block diversion is designed to be removed after the irrigation season in the
fall
For more information, please contact:
Tom
Phone:
(406) 444-5484
E-mail:
thughes@state.mt.us
Marcie Murnion, Gallatin Conservation
District
Phone:
(406) 522-4011
E-mail:
marcie.murnion@mt.nacdnet.net