Chin Reservoir is an off-stream storage reservoir located roughly in the middle of the St. Mary River Irrigation District (SMRID) system approximately 10km southeast of the Town of Coaldale. Chin Reservoir is the largest off-stream reservoir within the SMRID and has a current storage volume of 154,320 ac-ft (190,350 dam3) at the operating FSL (Full Supply Level) of 861.40m. Chin Reservoir is currently impounded by two dams: Chin West Dam and Chin East Dam.
The dams were completed in 1955 and no major modifications have been completed since construction. Water enters Chin Reservoir from the SMRID main canal, through the Chin Hydro Plant located in SW-26-8-18-W4 and/or Chin Chute located in SE-26-8-18-W4. The only outlet on the reservoir is the irrigation outlet structure on Chin West Dam, which discharges into Stafford Reservoir, supplying the main canal.
Chin West Dam
Rehabilitation of the Chin West dam and is associated structures is planned as part of the project. The associated structures are:
- Chin Chute, constructed in 1953, is reaching the end of its service life and lacks sufficient capacity.
- The irrigation outlet that discharges to the downstream Stafford Reservoir was also constructed in 1953. Like the Chin Chute, the irrigation outlet is reaching the end of its service life and is undersized to meet downstream demand during years when Chin Reservoir levels fall.
- The Chin West dam, constructed over a 3-year period ending in 1955, settled up to 2m post construction. To accommodate a higher water level, the dam will be re-established and raised to an appropriate height.
- Minor work will be done at the Chin Hydro facility on an as needed basis to accommodate the project.
Chin East Dam
The East Dam work will include:
- Construction of a new East Dam located approximately 10km downstream of the existing Chin East Dam. The dam will be constructed of earthen fill and will include an emergency overflow structure to accommodate the inflow design flood.
- Post dam construction the reservoir Full Supply Level will be raised ~2.6m to 864.00m.
- The newly inundated area of the reservoir is situated entirely on privately owned land.
- The reservoir enlargement increased the surface area of Chin Reservoir by 42%.
Natural Resources Conservation Board (NRCB)
Role: The Natural Resources Conservation Board Act (NRCBA) requires the NRCB to determine whether projects that require an environmental impact assessment (EIA) under the Environmental Protection and Enhancement Act are in the public interest. Projects that are reviewable under the NRCBA and its regulations are mining, forestry, water management, and recreation. Proposals may also be referred to the Board by Order in Council.
Role: An Environmental Impact Assessment (EIA) is required where a proposed industrial project could result in significant adverse environmental effects. The environmental assessment process allows companies and government decision makers to examine the effects that the proposed project may have on the environment and determine if the project is in the public’s interest.
Alberta Environment Page: https://www.alberta.ca/environmental-impact-assessments.aspx
Impact Assessment Agency of Canada (IAAC)
Role: The federal body accountable to the Minister of Environment and Climate Change. Serving Canadians by delivering high-quality impact assessments that look at both positive and negative environmental, economic, social, and health impacts of potential projects. The IAAC contributes to informed decision making on major projects in support of sustainable development in Canada.
Chin Project Page: https://iaac-aeic.gc.ca/050/evaluations/proj/83562