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

4.1.3
Wangan and Sanborn brooks are separated by a low-relief height-of-land
traversed for approximately a 500-700 ft. distance by a narrow, low lying depression
through the forested esker valley. The depression extends from a sharp bend in Sanborn
Brook westerly to the vicinity of a beaver flowage which is a tributary to Wangan
Brook. The beaver dam emits discharge down a short connector stream channel to
Wangan Brook.
On the date of the May site visit, Wangan Brook flow was gaged at 3.3 cfs and
flow in the connector channel was 1.5 cfs. During the July site visit, Wangan Brook
was not gaged, but estimated to be discharging about 10-15 cfs, and showed evidence of
having recently receded from slightly over its banks. The reach of Wangan Brook at the
toe of the esker that curves near the beaver pond shows evidence of stream evulsions;
an abandoned channel of the brook appears to have received overflow that potentially
funneled into the lower end of the beaver flowage under extremely high runoff
conditions.
Wangan and Sanborn Brooks
Most of the connector channel is trapezoidal-shaped, and comprised of
vegetated, earthen banks and fine substrates. A staff gage in the connector stream
indicated that the water level had risen 2 inches relative to May water levels in response
to increased July outflow from the beaver flowage. The beaver pond water elevation
had risen by approximately one foot.
At the point of confluence, both Wangan Brook and the beaver flowage
connector channels are sufficiently deep, wide and slow-flowing enough to
accommodate volitional passage of adult fish, including northern pike under the
observed flow conditions. Two barriers in the connector channel were surveyed in May
to determine if pike could gain access to the beaver pond (Appendix 1). Although the
beaver flowage is part of the Wangan Brook watershed, it is perched close to a shallow
watershed divide. Thus the surrounding topography was revisited in July (after heavy
rains increased surface runoff) to empirically observe if low lying areas between the
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