|Citation||Lewis, A. 2005. Developing measures for the aquatic habiat attribute in BC Hydro's 2005 integrated electricty plan. Prepared for BC Hydro.|
|Abstract/Description or Keywords||The environmental objective for the 2005 Integrated Electricity Plan (IEP) defined by the
Provincial Committee of the IEP is to incorporate environmental impacts into the
consideration of electricity portfolios. The dominant legislation regulating impacts to
aquatic (fish) habitat is the Federal Fisheries Act: most new energy resource options have
the potential to cause impacts and thus violate the Fisheries Act.
Biomass, customer cogeneration, and Power Smart options typically pose no risks to aquatic
habitat. However, energy generated from natural gas, coal, large hydro, run-of-river small
hydro, wind, and geothermal sources all require infrastructure, including access roads and
transmission right-of-ways. In addition, large hydro and small hydro resource options rely
on water as the ‘fuel’ for energy generation, which they use non-consumptively, returning the
water to the river channel, but nevertheless creating potential impacts to aquatic habitat.
These impacts are mitigated through environmental design to meet regulatory requirements,
then any residual impacts are offset through the provision of compensation at a rate
sufficient to offset the risk of failure in either the assessment process or the provision of
mitigation and compensation Despite these environment regulations and the application of
best management practices, there are risks that impacts will occur.
Potential measures that can describe the risks to aquatic habitats from different resource
options are limited by the existing information on the proposed resource options and our
knowledge of links between physical changes caused by these projects and the productive
capacity of aquatic habitat. These links have been studied and are reported in the scientific
literature and in regulatory agency data.
The primary measure that can be derived from the IEP resource options database is the
surface area of aquatic habitat potentially affected by the development. Surface area is the
fundamental metric describing aquatic habitat and is proposed here for use as the
quantitative measure to describe aquatic habitat. Qualitative comparisons of the nature of
impacts between large and small hydro should also be considered when making decisions
based on the quantitative measures.
Surface area measures relate primarily to small hydro developments, because these projects
have direct effects on aquatic habitat, and also because there are basic physical data available
for these projects that can be used to assess impacts. Comparable data are available for
relevant aspects of large hydro (Site C) and other resource options. The measures are
described and defined in this document, including the equation for calculating surface area,
the source of the equation and data inputs, and the assumptions inherent in the calculation.
Several variants of the surface area measures calculation are provided; each describes an
aspect of aquatic habitat impact expected for a resource option. The surface area measures quantify effects for: dewatering of the diversion section of small hydro projects; backwater
effects of large hydro projects; backwater effects at small hydro projects; footprint effects of
weirs/dam on all hydro projects; fish presence (a modifier of other impacts); and stream
crossings from access roads, transmission lines, and penstocks/tunnels. To calculate the
area of aquatic habitat potentially affected and therefore at risk from the development of a
resource option, the appropriate measure variants must be selected, combined, and
calculated to yield the area affected in hectares (ha). These measures should be applied
cautiously, influencing decisions only if qualitative information on potential impacts
provided in this document is also considered.
There are key questions and data gaps that affect decision making around potential aquatic
habitat impacts. Most of these questions and data gaps cannot be addressed within the 2005
IEP time frame; some may be addressed before the start of the 2007 IEP. Three key
uncertainties have been identified: 1) accuracy of physical data in the resource database; 2)
accuracy of the prediction of aquatic habitat effects from physical data; and 3) comparability
of predictions between different resource options. These uncertainties have been
acknowledged by defining the assumptions inherent to each measure proposed in this study.
For the comparison of small and large hydro projects, a qualitative assessment is provided
that evaluates the sensitivity of habitat affected by these resource options and evaluates six
aspects of aquatic habitat impact. This provides general guidance concerning the nature of
small and large hydro impacts that should be considered along with the quantitative
measures of aquatic habitat area that is potentially affected.
|Sub-watershed if known|