Table 2
Summary of Prereservoir Treatments
Description
Characteristic
Nutrients, organic matter, and silt income.
Targets
Forces deposition in siltation basin.
Modes of action
Strips silt and nutrients from water by marsh plants.
Precipitates phosphorus in incoming stream.
Highly effective, depending upon method chosen,
Effectiveness
season, and maintenance frequency.
Months to years.
Longevity
Loss of storage capacity of main reservoir if
Negative features
impoundment basin is constructed.
Maintenance requirements can be extensive.
Wetlands may lose effectiveness and will discharge
unwanted
Dissolved aluminum and/or aluminum hydroxide
may
be toxic to reservoir biota.
Unknown because of site specificity.
Applicability to
Not as applicable to high-volume, hydropower
reservoirs as to smaller recreational and potable
reservoirs
water supply reservoirs.
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