Environmental Assessment
Volume E-4.3
Tailings Facility
Fish and Aquatic Resources
Ambatovy Project
183
January 2006
4.3.5.6 Impact Analysis
Residual Impacts
Residual impacts of aquatic habitat loss as a result of the construction, operation
and closure of the tailings facility are summarized in Table 4.3-7.
The status of aquatic habitat in the tailings area is moderately well understood,
but the level of baseline information for some habitats (1
st
order streams and
wetlands) is low. The prediction confidence for impact ratings for habitats within
the disturbance area is high, as there is very limited potential for mitigation. The
prediction confidence for impact ratings for habitats downstream, is considered
moderate and is dependent on the assessment for hydrology and water quality.
Closure and reclamation goals are designed to establish suitable vegetation cover
to allow clean surface runoff to downstream basins.
Table 4.3-7 Potential Effects and Residual Impacts for Aquatic Habitat in the
Tailings Facility
Project Period
Potential Effects
Mitigation
Residual Impacts
construction
direct displacement and loss of
critical riparian and instream
and aquatic habitats
effects on downstream flow and
water quality during
construction
effects on aquatic and riparian
habitat during pipeline and road
construction
local water
management
high magnitude/long-term modification of
local water bodies and watercourses within
the tailing disturbance area
low magnitude / short-term habitat
disturbance during infrastructure
construction
low magnitude /long-term loss from
footprint of some facilities (bridges,
culverts)
operation
potential alteration of
downstream watercourse
habitats for aquatic biota as a
result of water flow and water
quality changes
potential water quality effects on
fish and aquatic biota
water management
erosion and
sediment control
systems
high magnitude / long-term modification of
downstream watercourses
low magnitude / medium-term modification
of downstream watercourses and wetlands
closure
changes in the landscape and
development of vegetative
cover to offer clean surface
drainage downstream
water management;
erosion control
on-site reclamation
low magnitude / long-term modification of
reclaimed topography and drainage system
An overall residual impact classification is presented in Table 4.3-8; the overall
environmental consequence scores were based on the screening system described
in Volume A, Section 7.
