AQUATIC ENVIRONMENT: CRITIQUE
The Assessment on the Aquatic Envrionment
This section includes a critique of the New Darlington Nuclear Power Plant Project environmental assessment focusing on the the three main effects of the project that were mentioned in the impacts section of the website. It also includes the proposed mitigation measures for the project.
Overall, the EIA of this project did a very good job in proposing various mitigation measures for every single one of their impacts on the aquatic environment, as well as selecting the various VEC's of the project. In addition, the fact that they chose to assess the effects of both cooling options (once-through cooling and towers) is a good idea, as it allows them to choose the option that will have the least impacts.
This section includes a critique of the New Darlington Nuclear Power Plant Project environmental assessment focusing on the the three main effects of the project that were mentioned in the impacts section of the website. It also includes the proposed mitigation measures for the project.
Overall, the EIA of this project did a very good job in proposing various mitigation measures for every single one of their impacts on the aquatic environment, as well as selecting the various VEC's of the project. In addition, the fact that they chose to assess the effects of both cooling options (once-through cooling and towers) is a good idea, as it allows them to choose the option that will have the least impacts.
Fish Mortality
VECs selected: Alewife, Round Goby
Fish mortality is a negative aspect of the project that cannot be avoided during the construction and operation phases of the project. During construction, underwater blasting will result in the death of several individuals of different species. The EIA mentions that various mitigation measures can be considered regarding the blasting program design in order to reduce fish losses. These included seasonal restrictions, fish deterrence or fish relocation. However, they do not go into detail on how they will perform these. Fish relocation in particular, doesn't seem very feasible in this case since the work will be performed at the nearshore area of the lake.
Regarding impingement and entrainment, the current Darlington Nuclear Generating Station was the first OPG station where fish protection issues were taken into account when deciding the design and shoreline location of the intake. When compared to other power plants on the Great Lakes, the intake design that will be used in this project has been very successful in reducing impingement at Darlington Nuclear Generating Station (SENES 2011). However, although it is much lower than other plants, the expected number of fish impinged by the once-through water cooling option ( 23,500 to 43,500 fish) is still a large number. On the other hand, if the cooling tower option is used in this project, the expected number of fish lost will be less at 10,000 fish per year.
VECs selected: Alewife, Round Goby
Fish mortality is a negative aspect of the project that cannot be avoided during the construction and operation phases of the project. During construction, underwater blasting will result in the death of several individuals of different species. The EIA mentions that various mitigation measures can be considered regarding the blasting program design in order to reduce fish losses. These included seasonal restrictions, fish deterrence or fish relocation. However, they do not go into detail on how they will perform these. Fish relocation in particular, doesn't seem very feasible in this case since the work will be performed at the nearshore area of the lake.
Regarding impingement and entrainment, the current Darlington Nuclear Generating Station was the first OPG station where fish protection issues were taken into account when deciding the design and shoreline location of the intake. When compared to other power plants on the Great Lakes, the intake design that will be used in this project has been very successful in reducing impingement at Darlington Nuclear Generating Station (SENES 2011). However, although it is much lower than other plants, the expected number of fish impinged by the once-through water cooling option ( 23,500 to 43,500 fish) is still a large number. On the other hand, if the cooling tower option is used in this project, the expected number of fish lost will be less at 10,000 fish per year.
Alewife (Alosa pseudoharengus) was selected as one of the VEC's by the EIA because it represents 85.9% of all the fish impinged. Furthermore, lake-wide populations of Alewife, an important species for the recreational salmon populations of the lake, are on the decline, which is why impingement losses can have an adverse effect on these populations.
The J.H. Campbell Power Plant in Lake Michigan used a wedge wire screen intake to successfully eliminate impingement and reduce entrainment without causing any unusual maintenance problems (Taft 2000). This project should have considered this option as an extra mitigation measure for impingement and entrainment losses of biota.
When we compare it to the Bruce New Nuclear Power Plant Project's EIA, the New Nuclear Darlington’s EIA doesn’t mention the extra mortality of local fish species through recreational harvest by increased numbers of anglers associated with an increased workforce. This is an important negative effect to fish populations that should be taken into account and for which mitigation measures should be put in place.
The J.H. Campbell Power Plant in Lake Michigan used a wedge wire screen intake to successfully eliminate impingement and reduce entrainment without causing any unusual maintenance problems (Taft 2000). This project should have considered this option as an extra mitigation measure for impingement and entrainment losses of biota.
When we compare it to the Bruce New Nuclear Power Plant Project's EIA, the New Nuclear Darlington’s EIA doesn’t mention the extra mortality of local fish species through recreational harvest by increased numbers of anglers associated with an increased workforce. This is an important negative effect to fish populations that should be taken into account and for which mitigation measures should be put in place.
Habitat Loss
VECs selected: Round Goby, Lake Sturgeon
To address habitat loss due to the removal of on-site ponds and shoreline loss, the EIA proposed the creation of new wetland areas at the site to compensate for the habitat loss. Regarding the removal of the ponds, vegetation will be relocated to these newly created areas. Even after considering the mitigation measures, the project's EIA still considers this loss in habitat as a residual negative effect of the project. However, by reading the description of the ponds, they don't seem to support any fish species and they are not very productive habitats. For this reason, we don't think that the loss of these ponds will be of great impact to the project site's ecosystem.
On the other hand, the loss of nearshore habitat could be of great impact for nearshore resident species at the New Darlington power plant. The species that is expected to be the most impacted is the round goby (Neogobius melanostomus), this is mostly because it is one of the most abundant species recorded at the site study area and relocation of this benthic species is not possible. The round goby is a recent invasive species that poses a big threat to the Lake Ontario ecosystem. However, it is now being considered an important species for its ability to readily consume a great amount of zebra mussels, another very destructive invasive species present in the great lakes (Djuricich and Janssen 2001). Therefore, losses in Round Goby numbers could increase zebra mussel numbers, which can be slightly detrimental to the ecosystem of our site. Furthermore, Lake Sturgeon (Acipenser fulvescens) populations are very low in the area and are considered threatened by the COSEWIC. Presence of juveniles at our site is a good sign that the population is recovering. However, the loss of 40 ha of nearshore habitat, in which Lake Sturgeon have been confirmed previously, can threaten these important species and hinder their recovery (Auer 1996).
Thermal Effects on Fish
VECs selected: Round whitefish, Lake trout
The Canadian Nuclear Safety Commission has stated that the current Darlington Nuclear Generating Station is employing the Best Available Technology in terms of thermal discharge effects. The New Darlington Plant will employ the same or even better technology than the DNGS. The discharge diffuser design chosen by OPG enhances the mixing of the thermal effluent with the lake water, therefore limiting the development of a thermal plume and preventing contact of heated water with the lake substrates. It prevents the dispersion of water more than 2°C above ambient beyond the mixing zone along the diffuser. For this reason the EIA concluded that effective mitigation of thermal effects on the aquatic habitat and VEC indicator species will be achieved without the need of additional mitigation measures.
However, research on round whitefish (Prosopium cylindraceum) has shown that a 2°C increase in substrate temperature can cause 50% of eggs to hatch earlier by 10 days as well as causing a 30% decrease in larvae hatched. This can cause indirect mortality to this species due to a mismatch in hatching and food supply (Patrick et al. 2013). The EIA states that the effect will not be significant because the increase in water temperature will be restricted only to the mixing zone of 50m west of the discharge. However, spawning of whitefish has been recorded at the project site location and it is known that this species is on the decline on Lake Ontario, therefore anything that increases their mortality or affects their spawning can have a deleterious effect on these declining populations.
VECs selected: Round whitefish, Lake trout
The Canadian Nuclear Safety Commission has stated that the current Darlington Nuclear Generating Station is employing the Best Available Technology in terms of thermal discharge effects. The New Darlington Plant will employ the same or even better technology than the DNGS. The discharge diffuser design chosen by OPG enhances the mixing of the thermal effluent with the lake water, therefore limiting the development of a thermal plume and preventing contact of heated water with the lake substrates. It prevents the dispersion of water more than 2°C above ambient beyond the mixing zone along the diffuser. For this reason the EIA concluded that effective mitigation of thermal effects on the aquatic habitat and VEC indicator species will be achieved without the need of additional mitigation measures.
However, research on round whitefish (Prosopium cylindraceum) has shown that a 2°C increase in substrate temperature can cause 50% of eggs to hatch earlier by 10 days as well as causing a 30% decrease in larvae hatched. This can cause indirect mortality to this species due to a mismatch in hatching and food supply (Patrick et al. 2013). The EIA states that the effect will not be significant because the increase in water temperature will be restricted only to the mixing zone of 50m west of the discharge. However, spawning of whitefish has been recorded at the project site location and it is known that this species is on the decline on Lake Ontario, therefore anything that increases their mortality or affects their spawning can have a deleterious effect on these declining populations.
For more information, please refer to the Aquatic Environment - Assessment of Environmental Effects Technical Support Document, and the Bruce Nuclear Power Plant Project Aquatic Environment Technical Support Document.