Upper Mattagami EA

Project Information

The Facilities
The Wawaitin, Sandy Falls and Lower Sturgeon Generating Stations are small run-of the-river hydroelectric facilities that have provided a clean and renewable source of power for over 90 years. All three facilities are now at the end of their designed service life. These three generating stations operate at 25 cycles and therefore the power cannot be used locally in Timmins and instead must be transmitted to Sudbury in order to convert the power to 60 cycles and then be injected into the power grid. Significant energy losses occur during the process of transmitting and converting the 25 to 60 cycle power. All three plants are in need of structural and electrical/mechanical repair in order to continue to provide Ontario with this clean and renewable source of power.

Wawaitin Generating Station
The Wawaitin Generating Station is a 10.4 megawatt facility located within the City of Timmins municipal boundaries approximately 25 kilometers southwest of the urban centre. The plant, placed in service in 1912, is accessed by a municipal road. The Wawaitin Generating Station has a main dam at the northern end of Kenogamissi Lake. The existing powerhouse is operated remotely. Plant operation is controlled to ensure optimal energy production, while satisfying concerns of Kenogamissi Lake cottagers regarding water levels and flooding concerns downstream at Timmins. Typically, water levels are not allowed to fluctuate more than 0.4 m in Kenogamissi Lake during the summer months, with sufficient water passage through the Wawaitin Generating Station (GS) and/or spilling to ensure adequate downstream supply to Timmins and the pulp and paper mill in Smooth Rock Falls. Water level fluctuations must all be in compliance with the Mattagami River System Water Management Plan.

The proposed Wawaitin GS is planned to be located adjacent and to the north of the existing powerhouse. The proposed Wawaitin GS will have two generating units with an approximate capacity of 15 megawatts. Water in the existing intake canal would be conveyed through the existing intake structure via a new steel penstock about 850 meters in length to the new powerhouse and the adjacent substation. The proposed facilities will be connected to the Hydro One Networks Inc. (Hydro One) Timmins Transformer Station at 27.6 kilovolts to feed into the Timmins local distribution system. This penstock system would be buried parallel and to the north of the existing twin penstocks that feed the existing Wawaitin GS. Some refurbishment to the existing dams will be required.

Sandy Falls Generating Station
The 3.0 megawatt Sandy Falls GS is located within the Timmins municipal boundaries approximately 10 kilometers northwest of the urban centre. The plant, placed in service in 1911, is well accessed by municipal roads. The Sandy Falls GS receives water upstream of a 216 meters long spillway weir dam across the Mattagami River. As a run-of-the-river plant, the Sandy Falls GS utilizes available water only. Water levels in the headpond are not controlled by plant operation, but are the result of natural water level fluctuations and/or upstream controls and activities. Water levels are maintained to provide sufficient water for Timmins by drawing down the upstream storages when inflows drop in late summer.

The proposed Sandy Falls GS is located adjacent to the east of the existing powerhouse and the new powerhouse will enclose one generating unit with a nameplate capacity of approximately 5.5 megawatts. A water canal will be used to convey water to the new powerhouse using the existing intake structures No. 2 and No. 3. The intake structures and weir dam will also need to be refurbished.

Lower Sturgeon Generating Station
The 5.3 megawatt Lower Sturgeon GS is located outside the municipal boundaries of Timmins and approximately 48 kilometers north of the City. The plant, placed in service in 1923, is accessed by a road west of Highway No. 655. The Lower Surgeon GS has a dam, 165 meters in length, constructed in three differently angled sections, extending across rock outcrops along almost the entire width of the river.

The existing powerhouse is operated remotely. As a run-of-the-river plant, there is no drawdown of the headpond. Any upstream water level fluctuations are the result of natural water levels and/or upstream controls or activities. In most years, sufficient water exists to operate the plant at full-load on a continuous basis. OPG attempts to pass at least 15 m3/s of water at all times for dilution of effluent discharge at the pulp and paper mill at Smooth Rock Falls. In late winter, the forebay is drawn down to provide water to Little Long GS downstream.

The proposed Lower Sturgeon GS is planned to be located at the site of the existing powerhouse and will be redeveloped to produce about 14 MW of power.

The Environmental Assessment

The redevelopment of the Wawaitin, Sandy Falls and Lower Sturgeon facilities subject to the requirements of OPG's Class Environmental Assessment for Modifications to Hydroelectric Facilities under the Ontario Environmental Assessment Act (EA Act).

An environmental assessment was conducted to examine the effects of the Project on the:

Aquatic Environment (water, fish and other aquatic life)

Terrestrial Environment (adjacent trees, vegetation and fauna)

Socio-Economic Environment (local economy, local social and economic uses)

Archaeological and Built Heritage (archaeological, building or structural resources.

Atmospheric Environment (air and noise).

Some field work was carried out in 2005, however extensive field work associated with assessing the effects of the Project was conducted in 2006. The effects of the Project both during the construction and operations phases have now been assessed and measures to mitigate, eliminate and reduce negative effects as well as enhance positive effects were identified in the ER. Field work indicated that the environmental impacts associated with the Project would be temporary and minor and could be mitigated.

One (1) ER was prepared for all three (3) generating stations.

Mattagami River System Water Management Plan

A Water Management Plan for the Mattagami River System has been developed and includes eighteen waterpower structures and facilities located along the river system that have influence on levels and flows. The Plan was the result of a partnership between Ontario Power Generation, the Ministry of Natural Resources and other private power producers which operate facilities along the river as well First Nations and the general public, which participated in the form of various advisory committees.

The Water Management Plan was prepared in accordance with the Water Management Planning Guidelines for Waterpower, as approved by the Minister of Natural Resources on May 14, 2002. The Ontario Lakes and River Improvements Act requires compliance by facility operators with the operating regimes (required flows) established in the Water Management Plans and a compliance monitoring program has been established.

June 2010- Notice of Minor Amendment Inspection

OPG, in consultation with the Ministry of Natural Resources (MNR), is seeking a minor amendment on a temporary basis to the Water Management Plan. This minor amendment will enable OPG to lower the approved minimum upstream water elevation of Lower Sturgeon GS from 257.70m to 256.47m from 1 July 2010 to 31 August 2010. The minor amendment is being sought to enable maintenance work on the spillway of Lower Sturgeon GS. A Notice of Minor Amendment Inspection providing details on the need for this temporary amendment has been issued by OPG through local papers and this website. The Notice is provided in the Notices/Decisions page.