Summary of the report on baseline surface-water-quality monitoring for the Petitot River basin

This page provides a summary of results from a study on baseline surface-water-quality monitoring, which took place in an area of shale gas development, in northeastern British Columbia.

Report on baseline surface-water-quality monitoring for the Petitot River basin and surrounding watersheds: Review of the potential impact of shale gas development in the Horn River basin in British Columbia (PDF, 2.90 MB)

In recent years, unconventional oil and gas resources (e.g., shale gas) have been developed in northeastern British Columbia. In a three-year project funded by Environment and Climate Change Canada and Natural Resources Canada, data were collected to assess and monitor baseline water-quality conditions in an area of unconventional oil and gas development, in northeastern British Columbia. In this report, this region refers to parts of the Petitot River, Fort Nelson River, Liard River, and Hay River basins.

Surface-water-quality assessment and monitoring of the Petitot and Fort Nelson river basins were completed. Surface-water-quality information was collected from January 2012 to March 2015. This included the collection of water-quality samples and benthic macroinvertebrates samples that were analyzed following Canadian Aquatic Biomonitoring Network (CABIN) biological assessment methods. The data will contribute to improving our understanding of the water quality and the health of ecosystems in the Petitot River, Fort Nelson River, Liard River, and Hay River basins.

Routine water-quality monitoring

The first part of the report presents and discusses routine monitoring of water quality: monitoring at regular intervals. The objective was to better understand water-quality conditions in the Petitot River basin and establish a long-term water-quality-monitoring site. To do this, baseline data were collected using a standardized set of physical and chemical variables. During the study period, routine water-quality-sampling sites were established in areas exposed to unconventional oil and gas activities. These sites included a variety of watersheds. Submersible loggers were also installed at sites to collect water temperature and specific conductance data. Specific conductance is the measure of how well water can conduct an electrical current and is related to the amount of ions in the water.

The results indicate that the water in the Petitot River basin is generally hard with high levels of dissolved organic carbon. Most of the chemical variables analyzed were below water-quality guidelines. The excesses of cadmium and iron are explained by the high amount of sediment during high-flow periods and the influence of wetlands and groundwater during low-flow periods.

Routine monitoring did not detect any major impacts related to unconventional oil and gas activities in the Petitot River basin. A long-term monitoring station was established at the furthest downstream site in the Petitot River basin (Petitot River, at Highway 77). This station was added to the long-term federal-provincial water-quality-monitoring network. The data are available on Open government.

Synoptic water-quality monitoring

The second part of the report presents synoptic water-quality monitoring: monitoring that is carried out by collecting many samples at different locations over a short period of time. The objective was to establish spatial patterns in water chemistry and any potential relationships between water quality and unconventional oil and gas activities. To achieve this, water sampling was performed during high- and low-flow periods and at different locations.

A series of samples were also collected along the mainstem Petitot River, at 20 kilometre intervals, from the Alberta border to the Highway 77 bridge. The goal was to capture potential step changes in water chemistry as the river flows through the gas production area. In addition, samples were collected from the outlets of smaller watersheds to represent a range of unconventional oil and gas activities and potential contamination.

Patterns in water chemistry in the mainstem Petitot River did not indicate contamination. In the smaller watersheds, possible indications of effects of unconventional oil and gas activities on surface-water chemistry were found. The data are available on Open government.

Biological water-quality monitoring

The third part of the report presents biological-monitoring results. The objective was to establish baseline or reference conditions based on the characteristics of benthic macroinvertebrate communities and their habitat and to develop a predictive bioassessment model to assess stream ecosystem health of the Liard River, Fort Nelson River, and Petitot River basins. Sampling was conducted using CABIN’s methodology for the sampling of benthic macroinvertebrates from rivers and streams (Environment Canada, 2012).

Sampling was conducted at 53 reference sites that are unaffected or minimally influenced by human activity. A total of 35 test sites were also selected across various unconventional oil and gas activities. The biological assessment predictive model developed for northeastern British Columbia provided a preliminary assessment of water quality and ecosystem health in the region. It is available on the CABIN website for more in-depth assessments going forward.

The biological community was different from what was expected if the ecosystem was not affected by environmental stress. However, most of the water-quality data measured at the test sites were within the same limits as the measurements taken at the reference sites. It is possible that climate-related hydrological changes had a confounding effect on ecosystems during the short duration of the study. Further assessments will be required to better understand this effect.

These data are available on Open Government.

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