Example 5: Price Creek, Montana
(Fouty 2003).
This study showed the impact of the
trapping of beavers, and their presence,
upon water depths (i.e., water stored).
Beavers were trapped out between 1994 and 1995, but the beaver dams inside the
cattle exclosure were still largely intact
and functional in 1995. In contrast, dams
were absent downstream of the exclosure
(Reach 1), though remnant dams had been
noted during the 1994 survey of Reach 1.
Table 3 shows the average water
depths and the variability in water depths
(standard deviation) in the three reaches
in 1995 and 1998. In 1995, the average
water depths in Reaches 2 and 3 (beaverdam
controlled reaches) were twice the
average depths in Reach 1 (no beaver
dams). In addition, the variability in water
depths in Reaches 2 and 3 was greater
than in Reach 1, indicating more variable
channel bed habitat with possible fisheries
and macroinvertebrate benefits. By 1998,
the dams in the cattle exclosure had either
completely disappeared or were actively
breaching. Water levels were now similar
in all three reaches. Figures 3 and 4 show
the visual difference between reaches with
and without beaver dams.