Operational Plan for the Restoration of Diadromous Fishes to the ...

A TSCF is considered here as an appurtenance to the Proposed Bypass to provide a means
for exclusion of non-indigenous fishes, including northern pike (Esox lucius) and black
crappie (Pomoxis nigromaculatus). These two species are herein collectively referred to as
target exclusion species. Relevant information documenting the presence of northern pike in
the Penobscot River watershed is presented in the Pushaw Lake Fisheries Management
Plan. This report documents the presence of illegally-introduced northern pike in Pushaw
Lake, which is a tributary to the Penobscot River, along with anecdotal reporting of northern
pike in the Penobscot River adjacent to Howland Dam.
Overlapping swimming abilities of the target passage species and the target exclusion
species preclude achieving the project objectives of upstream fish passage and exclusion
solely through the design of a bypass channel. Exclusion of non-native fishes is therefore
the objective of the TSCF facility.
The TSCF performance criterion is total (100 percent) exclusion of the target exclusion
species. The need for total exclusion is based on the assumption that introduction of even
small numbers of target exclusion species may result in reproduction in the Piscataquis
River watershed upstream from Howland Dam.
3 CONCEPTUAL DESIGN
A conceptual design of a TSCF was developed for the Proposed Bypass, including general
features and operational methods. The basis for this design is that total exclusion of the
target exclusion species cannot be achieved through the design of the Proposed Bypass
and therefore manual sorting of upstream passing fishes is required. As previously noted,
overlapping swimming abilities of the target passage and exclusion species preclude
exclusion based on hydraulic conditions in the Proposed Bypass.
A general requirement of the system would be that all or most of the flow be routed through
the TSCF trapping component during periods of low flow to maintain upstream fish passage
during these periods.
Alternative means for excluding the target exclusion species, such as electrical barriers,
were briefly considered as part of this analysis but were determined to be incapable of
achieving total exclusion.
3.1 Overview
This section presents a general overview of the conceptual TSCF. The conceptual TSCF
includes a trapping system with an adjacent sorting area located on the right (northwest)
side of the upstream limit of the Proposed Bypass.
Based on a review of information presented in the Conceptual Design Plans by MMI dated
March 2008 and other relevant materials, routing the entire flow of the Proposed Bypass
through a TSCF does not appear to be practical. The proposed design therefore provides for
routing of limited attraction flow through the trap system and the balance of the flow entering
the Proposed Bypass over an adjacent weir. The weir would be designed to preclude
upstream passage by some or all of the target passage species and all of the target
exclusion species. The balance of the flow would be routed around the trapping facility
through the TSCF conveyance channel with means to preclude upstream passage of all
target species or allow upstream passage for a subset of target passage species. The only
target passage species capable of upstream passage over a weir designed to exclude
northern pike would be Atlantic salmon. Alewife and American shad are expected to
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