Appendix A. Regulation of the HBDB. Chapter 3: Freshwater System Appendices. Reindeer Lake

Transcription

1 Appendix A Regulation of the HBDB Reindeer Lake As the largest lake in the Churchill River Basin, Reindeer Lake serves as an off-channel storage reservoir for Island Falls GS, a hydroelectric generating station located on the Churchill River (Nelson River basin) approximately 45 kilometres upstream of the Saskatchewan-Manitoba boundary. Island Falls GS was originally built by the Churchill River Power Company (CRPC) to supply electricity for the town of Flin Flon and the smelter of the Hudson Bay Mining and Smelting Company. Construction of Island Falls began in 1928 and was completed in 1930 with a powerhouse of three units. Four additional turbines were installed during the period of (Crippen Acres, 1983). For the first 10 years of operation, Island Falls GS operated without the regulation of Reindeer Lake and it was quickly determined that dependable hydropower generation could be increased if it was used as a storage reservoir. CRPC began construction of a series of crib dams in 1937 to impound Reindeer Lake and by 1942 had completed the construction of Whitesand Dam, a concrete control structure equipped to regulate outflows of Reindeer Lake for increased dependable winter flows (Crippen Acres, 1983). SaskPower took ownership of Island Falls GS in 1981 and assumed operations of the plant and Whitesand Dam in In 1975, a study was undertaken jointly by the Canada, Saskatchewan, and Manitoba governments to determine the social, economic, and environmental impacts of hydroelectric development on the Churchill River. As a part of this study, work was undertaken to reconstruct and simulate the hydrologic regime of the Churchill River with the regulation of Reindeer Lake and Island Falls GS removed. The study found that regulation of Reindeer Lake had resulted in an overall increase in winter and early spring flows on the Churchill River, with a corresponding decrease in summer and autumn flows (Hofer, 1975). Lake Diefenbaker Located on the South Saskatchewan River upstream of the City of Saskatoon, Lake Diefenbaker is the largest body of water in southern Saskatchewan. The reservoir operates to provide irrigation

2 for Central Saskatchewan and the Qu Appelle Valley, as well as providing other benefits to the area including hydroelectric generation, water supply, flood control, and recreation facilities. Lake Diefenbaker is comprised of multiple structures at both Gardiner Dam/Coteau Creek GS, the primary outlet to the South Saskatchewan River; and the Qu Appelle River Dam, a smaller earth fill dam constructed to contain the lake and allow for controlled diversion releases to the Qu Appelle River through a gated diversion conduit. Construction of Lake Diefenbaker began in 1959, both dams and the Gardiner spillway were largely complete by 1967, and by 1970 the reservoir was fully impounded (Saskatchewan Watershed Authority, 2012). The relatively large storage capacity of Lake Diefenbaker has allowed for significant control of outflow from the lake, reducing the fluctuations of discharge from variable inflows to the lake while meeting water level and outflow targets and respecting dam safety requirements. In general, the reservoir is operated such that high inflows in late spring/early summer are captured in storage and released continuously throughout the rest of the year. The result of this regulation has been a significant dampening of extreme high and low flow events and an overall flattening of the annual hydrograph shape (Saskatchewan Watershed Authority, 2012). Lac Seul Lac Seul is a reservoir located on the English River that is operated to provide storage for the benefit of hydroelectric generation on the English and Winnipeg Rivers. Outflows of Lac Seul are controlled through the operation of two generating stations situated at the lake s outlet, Ear Falls. The original spillway and powerhouse at Ear Falls GS were built in by the Hydro-Electric Power Commission of Ontario; with reservoir filling completed in In early 2009, the construction of an additional powerhouse, Lac Seul GS, was completed (LWCB, 2016). In addition to natural inflows from the Upper English River, Lac Seul receives inflows diverted from Lake St. Joseph via the Root River. This diversion has been in place since 1958 and operates to pass flow from Lake St. Joseph to Lac Seul for increased hydropower production on the English and Winnipeg Rivers. Control structures on the Root River and Albany River, the natural outlet of Lake St. Joseph, regulate the amount of water diverted to Lac Seul; however, the Root River diversion dam is fully open for the majority of the time, with more than 80% of the water from the Lake St. Joseph basin being diverted to Lac Seul (LWCB, 2016).

3 Lac Seul releases are regulated by the Lake of Woods Control Board (LWCB), subject to the terms of the LWCB Act as amended in 1958 and the operating range defined in the 1986 Orders-in- Council. Since its initial construction, Lac Seul has operated primarily to maximize hydropower production at downstream generating stations on the English and Winnipeg Rivers, though increasingly the needs of other users are being considered in regulation actions (LWCB, 2016). Since regulation, average monthly releases from Lac Seul have been typically greatest over the winter period when energy demand is greatest and inflows are the lowest, with flows reduced over the summer to allow for refilling of the reservoir to summer target levels. Lake of the Woods Lake of the Woods is the largest lake in the Winnipeg River basin and is an international waterway located on the Canada-US Border. The lake serves as a multipurpose reservoir, providing benefit to hydropower production on the Winnipeg River system, as well as recreational benefits to locals and cottagers in the area. With two main outlets located at the north end of the lake near the City of Kenora, Lake of the Woods discharges into the Winnipeg River, which flows onward through Manitoba and into Lake Winnipeg. Lake of the Woods eastern outlet was first partially controlled in 1892 and has been fully controlled since 1906 with the completion of Kenora Generating Station. The western outlet is regulated by the Norman Dam and Generating Station. Construction of Norman Dam began in 1893, but the powerhouse was not completed until 1925 (LWCB, 2016). Outflows from Lake of the Woods are regulated by the Lake of the Woods Control Board under a treaty between Canada and the United States. This treaty prescribes maximum and minimum levels, within which the lake must ordinarily be maintained, to best serve multiple uses (LWCB, 2016).. A large portion of inflow to Lake of the Woods is also regulated via the Rainy River system, which also spans the Canada-US border. Water levels and flows in this system are regulated according to rule curves established by the International Rainy Lake of the Woods Watershed Board (IJC, 2016) Cedar Lake Cedar Lake is a reservoir located on the Saskatchewan River just downstream of The Pas. The reservoir is used primarily for regulating upstream inflows from Saskatchewan and local runoff for hydropower generation at Grand Rapids Generating Station.

4 Grand Rapids GS was built during the period of and was the first northern hydroelectric generating station constructed by Manitoba Hydro after hydropower sites on the Winnipeg River were fully developed. Cedar Lake is primarily used as a seasonal reservoir to ensure an adequate supply of hydropower generation through the winter months. Responding to the operation of the Grand Rapids GS, Cedar Lake rises from April to November when inflows are greatest and energy demand is lowest. From November until March, Cedar Lake is drawn down as water is taken out of storage for energy production purposes. Refilling of the reservoir then begins in the spring depending on the timing and magnitude of the freshet and summer precipitation. The regulation of Cedar Lake have altered the timing and magnitude of the lake s outflows. Prior to the construction of the Grand Rapids GS, Cedar Lake water levels followed the natural hydrological cycle with the water levels rising in the spring, peaking in mid-summer and declining through the fall and winter. The downstream impacts of Cedar Lake are also compounded by the regulated of inflows from upstream reservoirs in Saskatchewan, which began at approximately the same time as the construction of Grand Rapids GS. As noted previously, the operation of Gardiner Dam/Lake Diefenbaker has significantly altered flows on the lower Saskatchewan River. These upstream regulation activities have generally resulted in higher winter flows and relatively lower summer inflows to Cedar Lake, as compared to what would have occurred prior to development. Lake Winnipeg As the sixth largest lake in Canada, Lake Winnipeg is the principal reservoir of Manitoba Hydro s hydroelectric generation network. Beginning in the late 1950s, Lake Winnipeg Regulation (LWR) was planned and developed by the governments of Canada and Manitoba to achieve two key objectives: to reduce shoreline flooding on Lake Winnipeg, and to advance the development of northern hydroelectric potential on the Nelson River. In 1970, Manitoba Hydro was granted a licence to regulate Lake Winnipeg outflow. LWR construction began in 1972 and was completed in LWR is an extensive engineered system of channels and structures that allows about 50% more water to flow out of the lake than would otherwise flow out naturally. Inflows into Lake Winnipeg vary tremendously from year to year, and with a relatively narrow operating range defined by the license, the reservoir is only capable of providing sub-annual storage. Seasonal effects of LWR operations include increased average outflows in the winter months and corresponding decreases in average summer outflows. The

5 improved outlet conveyance of Lake Winnipeg and restrictions on the operating range have also resulted in increased outflows during wet periods to provide flood relief around the shores of Lake Winnipeg, as well as reduced outflows during dry spells to provide low level support (Manitoba Hydro, 2014). Southern Indian Lake Located on the Churchill River, Southern Indian Lake (SIL) is a reservoir in Manitoba Hydro s system with the primary purpose of diverting flow from the Churchill River to increase flows and hydropower production of generating stations on the Burntwood and Nelson Rivers. The Churchill River Diversion (CRD) is comprised of two control structures and an excavated channel connecting which allows diverted water from SIL to enter the Nelson River system via the Rat and Burntwood Rivers. CRD is operated in conjunction with Lake Winnipeg Regulation to maximize overall power production on the lower Nelson River while adhering to the terms of the project s licenses. Churchill River Diversion construction began in 1972 and was completed in Prior to the Churchill River Diversion, river flows exited Southern Indian Lake at Missi Falls through two natural outlets at the east end of the lake and flowed down the Lower Churchill River into the Hudson Bay. The Churchill River Diversion has added an average flow of 767 cms to the Nelson River via the Burntwood River, with a corresponding reduction in the Lower Churchill River downstream of Missi CS. The combined effect of both LWR and CRD has typically produced higher Nelson River flows in the winter than would have occurred without regulation. Average outflows during the summer months are similar to what would have occurred without regulation, as typically Lake Winnipeg Outflows are reduced coincident to the increased diversion flows from Notigu CS. The Churchill River Diversion has also had a substantial impact on the Lower Churchill River flows, reducing overall volumes of discharge and significantly increasing streamflow variability (Manitoba Hydro, 2015b). Caniapiscau Located on the upper Caniapiscau River and within the Côte-Nord administrative region of Québec, this reservoir is the second largest in Canada. The reservoir, formed by two dams and 43 dikes, services the Brisay generating station and the downstream La Grande complex, providing

6 up to 35% of Hydro Québec power production. It was the largest (in surface area) built as part of the James Bay Project. Filling a natural (glacial) depression in the highest part of the Laurentian Plateau on the Canadian Shield, the reservoir has a local catchment area of about 36,800 km 2 and a total capacity of 53.8 billion m 3 (Hydro Québec, 2016). La Grande 3 (LG 3) and Robert Bourassa Reservoir Robert-Bourassa Reservoir is a man-made lake situated downstream of the Canipiscau Reservoir and similarly feeding the La Grande Complex (a total of eight generating stations); constructed as part of the James Bay Project, and one of the largest hydroelectric systems in the world. The La Grande Complex of generating stations drains westerly along the eastern shore of James Bay. Robert-Bourassa reservoir, constructed from 1974 to 1978 to feed the Robert-Bourassa and La Grande-2 generating stations, has a maximum surface area of 2,835 km 2 and total estimated capacity of 61.7 billion m 3. Forming the reservoir is the main dam and 31 smaller dikes. Together the generating stations, along with the La Grande 2-A (commissioned in 1991 to 1992), generate a combined 2,106 MW of power (Hydro Québec, 2016). La Grande-3 generating station resides on the La Grande Rivière upstream of Robert-Bourassa reservoir. The LG-3 hydroelectric generating station was commissioned between 1982 and 1984 and can generate up to 2,419 MW of power, with the La Grande Complex system having a total installed generating capacity of 16,527 MW. The La Grande Rivière watershed covers a region approximately 177,000 km 2 in size, or 11% of the total area of Québec. La Grande-1, also part of the James Bay Project, is the last generating station along the La Grande Rivière before James Bay. Commissioned between 1994 and 1995, the station installed capacity is 1,436 MW and is one of two generating stations that are run-of-the-river within the James Bay Project relying on water flow in the river, controlled by upstream reservoirs, to generate power. Eastmain The Eastmain River resides in northwestern Québec, naturally flowing approximately 800 km west into James Bay, and having a catchment area of approximately 46,400 km 2. In the 1980s, Hydro Québec constructed the Eastmain reservoir which diverts the river 41 km northwards to the Opinaca Reservoir, feeding the Robert-Bourassa Reservoir and La Grande Complex of generating stations (Hydro Québec, 2016). Eastmain-1 reservoir has a surface area of approximately 600 km2

7 and is formed by the main dam and a total of 33 dikes. Eastmain-1 powerhouse, located approximately 800 km north of Montréal, is equipped with three turbines generating a total of approximately 480 MWh of electricity, with the construction of Eastmain-1-A powerhouse (in 2012) increasing total power production to 6.3 TWh per year. Construction of Eastmain-1-A saw a portion of flow from the Rupert River diverted into the Eastmain-1 reservoir to sustain power production (Tremblay et al, 2014). Mistassini Lake Though not a regulated system in itself, Mistassini Lake is important for the Hydro-Québec s system due to it being the largest (by surface area) natural lake in Québec, with significant storage volume. Mistassini Lake s primary outflow point is the Rupert River, controlled by Rupert Dam, flowing downstream in a westerly direction before entering James Bay. Since 2009, downstream of Mistassini Lake, approximately 70% the natural flow of the Rupert River has been diverted northwards to the Eastmain River to feed the Eastmain-1-A development and La Grande hydroelectric project as part of the Eastmain-1-A/Sarcelle/Rupert Project (Hydro-Québec, 2016b). The lake is an important natural headwater pond for the Eastmain-1-A.

8 Appendix B Methodology for Historic Streamflow Trend Analysis A total of 21 rivers (Table B-1) are used to assess recent characteristics and trends in river discharge into Hudson Bay. The rivers are selected based on gauged data availability, gauged area, gauge proximity to Hudson Bay (including James Bay), record length, and data quality. Of note, there are very limited streamflow data for rivers draining into Hudson Bay prior to 1964 while recent (2014 onward) gauged data remain unavailable at this time, limiting the study period to 50 years. Time series of annual and seasonal discharge are created based on observed daily streamflow data for 1964 to 2013, then gap-filled (Déry et al. 2005). Here winter refers to the months of January, February and March, spring comprises April, May and June, summer includes July, August and September, and winter comprises October, November and December. Statistics of mean, standard deviation (SD) and coefficient of variation (CV) of annual/seasonal discharge are assessed for all rivers draining into the Bay. The Mann-Kendall Test (MKT) is then used to assess trends in annual/seasonal discharge, with p < 0.05 considered statistically-significant (Mann 1945; Kendall 1975; Déry et al. 2005). The effects of autocorrelation on trend analyses are minimized using a method developed by Yue et al. (2002). Trends are reported as percent changes in annual/seasonal river discharge between 1964 and Table B-1: The 21 HBDB rivers used in the streamflow trend analysis. River Outlet Province/ Territory Drainage Area, DA (km 2 ) Rank (DA) Mean annual discharge, Q (km 3 ) Rank (Q) Albany JB ON 118, Attawapiskat JB ON 36, Broadback JB QC 17, Chesterfield Inlet HB NU 259, Churchill HB MB 288, Eastmain JB QC 44, Ekwan JB ON 10, Grande Rivière de la Baleine HB QC 43,

9 Harricana JB QC 21, Hayes HB MB 103, La Grande Rivière JB QC 96, Moose JB ON 98, Nastpoca HB QC 12, Nelson HB MB 1,125, Nottaway JB QC 57, * 6 Pontax JB QC 6, Rupert JB QC 40, Seal HB MB 48, Severn HB ON 94, Thlewiaza HB NU 27, Winisk HB ON 54, Appendix C To come with Section 3.4 (end of summer/early fall) HYPE model setup Model Calibration/Validation