Construction and operation of hydroelectric projects naturally involves effects to the nearby environment. In Canada, a number of parameters must be monitored to evaluate the effectiveness of mitigation and compensation measures undertaken by project owners.
By Elizabeth Ingram
In Canada, hydro project owners and operators must meet requirements under the Canadian Environmental Assessment Act and Fisheries Act. Among these are the need to monitor a project's effects on fish and fish habitat, to provide the data needed to complete an environmental impact assessment.
In 2012, scientists with Ecofish Research Ltd. completed a report for Fisheries and Oceans Canada (DFO) entitled "Long-Term Aquatic Monitoring Protocols for New and Upgraded Hydroelectric Projects." The goal of this report was to "identify suitable methods to evaluate the effectiveness of mitigation and compensation activities undertaken during the development and operation of a project, and to evaluate the project's effect on fish and fish habitat." The document is also intended to promote standardized monitoring methodologies that create consistency in regulatory requirements and allow for the comparison of data across multiple projects.
The geographic focus of this document is British Columbia and the Yukon Territory, although it may apply elsewhere in Canada.
Environmental monitoring parameters
DFO's Fish Habitat Management Program is intended to conserve and protect fish habitat with a view to ensuring the sustainability of Canada's fisheries resources. Monitoring is needed to establish: key indicators by which regulatory agencies can measure compliance, tools that can be used to evaluate the success of mitigation and compensation measures designed to minimize or offset environmental impacts, and a mechanism for improving project management through evaluation of effects and integration of corporate learning.
What parameters are monitored in Canada?
The first set below are primary parameters to be included in the monitoring program for a new or upgraded project sited within a stream channel.
- Water quantity, including instream flow and ramping rates. Instream flow defines and forms fish habitat and influences productive capacity. Construction and operation of hydro projects alters several aspects of the hydrograph. Real-time flow data will be monitored through the life of the project to ensure compliance with the water license and to provide measures that will assist in interpreting changes in biological components of the monitoring program.
With regard to ramping rates, rapid changes to stream flow can dewater habitat and strand fish, which may lead to mortality. Potential stranding effects are mitigated by controlling the rate of operational flow change or flow ramping. Monitoring of ramping rates applies continuously throughout the life of the project.
- Mitigation and compensation measures. For many projects on waterways that contain fish, mitigation measures may include screens that prevent entrainment, as well as a fishway to allow fish to move upstream and downstream. Condition of the screen and fishway will be inspected annually and factors that may impair, delay or block fish migration be addressed to minimize disruption. Compensation habitat is often required to offset negative impacts that cannot be avoided or mitigated against. Monitoring may include verification of proper design and construction and an "as-built" survey to ensure the quantity of habitat constructed complies with the authorization.
- Riparian habitat. It is necessary to measure the footprint impact of a hydro project once construction is complete. Information collected ensures compliance with the project certificate and provides insight into the accuracy of the predictions made in the EIA.
- Water temperature. The reduction of water flows associated with run-of-river projects can increase or decrease stream temperature, depending on the season. Monitoring water temperature throughout the year allows detection of changes compared to baseline levels, and these changes can be factored into operational protocols and support the analysis of other monitoring components, such as invertebrate and fish abundance.
- Stream channel morphology. Hydro projects can impact channel stability and geomorphology, as well as sediment transport and deposition. A stream morphology assessment should be conducted after the first large flood event to occur after project commissioning or five years after construction, whichever comes first. A report should be produced detailing changes in stream channel morphology observed, concerns identified from a fish habitat perspective and a reassessment of the long-term impacts likely to result from project implementation.
- Fish community. For projects on fish-bearing streams, construction and operation can impact various metrics of fish community health, including abundance, density, condition, biomass, size at age, distribution, timing of migration and survival. Monitoring should occur at sites previously sampled to develop baseline data, with consistent timing across years. Fish abundance will in general be monitored one, two, three, five and 10 years post-construction.
This next set are secondary parameters for stream-based projects. Whether these are required depends on potential residual effects identified in the EIA.
- Water quality. Hydro plants can affect water quality by altering the volume of water in a channel or by returning water of altered quality to the channel. Monitoring is required if the EIA identified parameters that may be affected to a degree that the productive capacity of fish habitat may be adversely affected.
- Invertebrate drift. Macroinvertebrates and their habitats are included in instream flow assessments because salmonid growth and abundance are correlated to the abundance of drifting invertebrate prey. If long-term monitoring is required, sampling should occur in years one through five, with samples collected from the same site as those used during baseline surveys.
- Species at risk. Hydro projects can impact species at risk through habitat loss or degradation. The project proponent must identify any species at risk in the project area and gather baseline data and perform monitoring designed for that species and its habitat requirements, behavior and vulnerability.
Separate parameters will be monitored for projects at the outlet of a lake or those creating new reservoirs. The first set listed below are the primary parameters.
- Physical lake characteristics. As part of the EIA process, it is necessary to provide information on the characteristics of the lake and predict what impact the project will have on the physical aspects of the lake. Changes from storage operations are expected to be minimal and occur over a long period of time. A bathymetric survey and review of physical parameters is required every five years after project commissioning.
- Water quantity. The guidelines for impact assessment require a minimum of one year of on-site hydrometric data, but at least two years should be collected given that lake elevation and discharge data are critical to the interpretation of changes in other monitoring components.
- Limnology and water quality. Patterns of water storage and release that vary from natural conditions can alter water quality in a lake or reservoir. Thus, water quality and phytoplankton will be monitored in years one through five after project commissioning, after which the need for a water quality monitoring program should be reassessed.
- Fish habitat. The impacts to fish habitat from water retention and release are likely to be concentrated in the littoral zone, which provides the majority of fish spawning and rearing habitat within lakes. Littoral zone mapping and habitat surveys should be conducted to provide a baseline and repeated two and five years after project commissioning.
- Fish community. Effects on fish community health within a lake or reservoir are expected to result from changes in water quality and temperature, zooplankton and benthic invertebrate abundance and diversity, and habitat availability and accessibility. Fish community health will be monitored one, two, three, five and 10 years after construction.
This next set is secondary parameters for projects involving a lake or reservoir.
- Zooplankton and benthic invertebrates. Long-term monitoring is likely to be required if the EIA determined that the project may adversely affect these populations to the extent that the productive capacity of fish habitat may be reduced. Sampling will be conducted in years one through five.
- Species at risk. Water storage areas can impact species at risk, particularly if inundating large areas of terrestrial habitat or significantly altering water levels in existing lakes. Monitoring should be designed for the species at risk.
This document identifies monitoring protocols designed to uncover key variables, assist the planning and design of baseline and long-term monitoring programs, and provide technical methodology and analysis tools. However, proposed monitoring design must maintain flexibility and adaptability to handle major differences between projects and to incorporate new knowledge and methodologies as they develop.
Lewis, F.J. Adam, et al, "Long-Term Aquatic Monitoring Protocols for New and Upgraded Hydroelectric Projects," Ecofish Research, 2012, www.pac.dfo-mpo.gc.ca/habitat/docs/hydropower_long-term_monitoring_protocol.PDF.
Elizabeth Ingram is senior editor of Hydro Review.