Coefficient of
Determination
N
Equation
State
26
log
= 0.42 log SD + 0.41
0.71
Florida
55
log MDC = 0.79 log SD + 0.25
0.57
Wisconsin
SD is the Secchi disc depth in meters.
where
Thus, a Wisconsin lake with a mean Secchi disc depth of 6.6 ft (2.0 m)
should have few submersed macrophytes beyond a depth of 9.8 ft (3.0 m), sug-
gesting that sediment removal in shallow, macrophyte-infested areas to this
In the Florida
depth might produce significant relief from these plants.
lakes, a depth of 11.5 ft (3.5 m) might have to be achieved for submersed
macrophyte control.
Effectiveness and Costs
.
Sediment removal is one of the most effective and commonly used methods
of improving reservoirs.
In most situations where increased depth or storage
capacity is desired, or where toxic materials must be removed, sediment
removal is the method of choice.
In smaller reservoirs, it may be economi-
cally and environmentally feasible to dredge the entire reservoir.
As the
volume of material to be removed increases, so does cost and, more signifi-
cantly in many cases, so do problems of disposal.
Environmental impacts are
often short-lived, or can be minimized, assuming that the method is used
properly and that adequate containment areas and discharge treatment are
available.
Negative environmental impacts are most often associated with dis-
posal, and feasibility for any situation may turn on this issue.
Case
histories of dredging projects are described in Peterson (1981) and Cooke
et al. (1986).
Sediment removal has been carefully examined for costs, and detailed
reviews are found in Peterson (1982) and Cooke et al. (1986).
Cooke et al.
(1986) list six factors that influence dredging costs: (a) type of equipment
used,
volume of material to be removed,
(c) availability of a containment
site, (d) density of material to be removed,
(e) distance to containment area,
and (f) ultimate use of removed materials.
Saucier et al. (1978) have indi-
cated that costs are also reflected in the price of land for disposal sites,
78
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