Answer: There are a number of factors that contribute to the uncertainty in 60-day forecasts, and in particular spring forecasts - e.g. ground moisture levels and frost depth, how fast will the snow melt, how much rain will fall, and when will it fall (on frozen or thawed ground), etc. It is true that there is a lot of snow in Winnipeg and west of us in southern Saskatchewan, however the rest of the Lake Winnipeg watershed has about normal levels of snow.

In developing our operating plan for Jenpeg outflows, we account for:

• the amount of water flowing into Lake Winnipeg, which includes spring freshet volumes and is based on planned regulated flows from upstream (Saskatchewan and Ontario);
• tributary flow forecasts from the Province (Red, Assiniboine, Dauphin Rivers);
• historical data;
• existing snowpack information.

We recently increased our planned outflows through Jenpeg to account for the potentially higher than normal inflows with this spring's freshet. For April, the planned Jenpeg outflows are above upper quartile levels for this time of year (upper quartile refers to the top 25 per cent of flows). 

Answer: The "Save My Lake" video produced by Stornoway Productions and narrated by David Suzuki casts Manitoba Hydro and our operation of the Lake Winnipeg Regulation Project in a sinister way. It alleges that we keep the level of the lake high and don't let water flush through, which holds nutrients in the lake and harms the Netley Marsh. These allegations are not based on facts.  

The Lake Winnipeg Regulation Project consists of a series of floodway channels at the north end of the lake and a control structure (dam) located 100 km north of Lake Winnipeg at Jenpeg.  (Note the dam featured in the Save My Lake video is actually our Long Spruce Generating Station, located closer to Hudson Bay on the Nelson River. Long Spruce has absolutely no effect on Lake Winnipeg. The video suggests that there is a dam right on Lake Winnipeg, which there is not.)

The purpose of the these floodway channels is to allow more water to flow out of the lake, especially during winter. In wet periods, like we have experienced since the 1990s, LWR has actually increased flushing of water from Lake Winnipeg and has kept the water level of the lake lower than it would have been without LWR in place. This wet period has also negatively affected the Netley Marsh as it has not allowed for a drawdown of water to promote marsh plants to reestablish.

Since 1976, Manitoba Hydro has kept the level of the lake from reaching the extreme highs and, to a lesser extent, extreme lows that it would have, which would have some affect on the marsh. However marsh researchers, such as Dr. Richard Grosshans and Dr. Gordon Goldborough (both featured in the video), indicate the marsh has been in decline since 1922 due to a number of factors - the Netley Cut, discontinuation of dredging at the mouth of the Red River, the invasive fish species the Common Carp, isostatic rebound, and Manitoba Hydro regulation.

The science looking into Lake Winnipeg agrees that increased flows and nutrient levels in the Red River flowing into Lake Winnipeg is the most significant issue that should be addressed to protect Lake Winnipeg. The impacts on the health of the lake ecosystem from Manitoba Hydro are not fully understood, however contrary to the Save My Lake video, even if there are impacts, they are considered small in comparison to these other impacts.

Manitoba Hydro is a major supporter of independent research to better understand the lake ecosystem, to develop appropriate land use policies and for public education.

More on Lake Winnipeg Regulation, including a link to the video "Lake Winnipeg Regulation: A Closer Look".

If you would like a DVD mailed to you, email your request to publicaffairs@hydro.mb.ca.

Answer: Heavy precipitation beginning in early October caused increased inflows to Lake Winnipeg such that inflows were matching outflows, keeping the level of the lake fairly stable through October. Since October inflows have been declining steadily, however through most of November outflows were reduced to help develop a stable ice cover at the outlet of Lake Winnipeg (a stable ice cover is required to maximize water flow out of the lake). During this time, the water level  of Lake Winnipeg remained relatively steady.

Currently, outflows from Lake Winnipeg are close to 92,000 cubic feet per second and Jenpeg Control Structure and Generating Station flows will remain at maximum discharge for the remainder of the winter. Current projections have the level of the Lake at about 713.6 for April 1st, 2013.

Our standard operating practice is to be at maximum discharge at Jenpeg from about mid-December throughout the winter in order to get as much water out of the lake and downstream to our large generating stations on the lower Nelson River. Note though that the "maximum discharge" amount decreases throughout the winter as the build-up of ice at the outflow of Lake Winnipeg and downstream constrains the amount of water flow – so that by April we will only have about 70,000 cfs flowing out of the lake.

Answer: The current level of Lake Winnipeg is 714.5 ft asl, which is within about a half foot of the long term average level for this time of year since records began in 1913. With current outflows, water levels on Lake Winnipeg are declining and are forecast to fall below elevation 714 in November and will continue to fall throughout the winter. Based on this scenario, it would not be prudent to increase outflows to drop the lake further as it would have the effect of adversely affecting energy security, downstream communities and environment.

Please note that beach enthusiasts can be very pleased with the performance of the Lake Winnipeg Regulation (LWR) project for this summer’s beach season. Drainage of the record amount of water that flowed into the lake during the past two years was significantly enhanced by the LWR flood channels constructed at the north end of the lake, resulting in lower water levels, reduced shoreline erosion and more beach.

More about Lake Winnipeg Regulation.

Answer: There is a common misperception that hydro-electric development raised the level of Lake Winnipeg. In fact, a key reason for constructing the Lake Winnipeg Regulation Project was for flood relief to address overland flooding that occurred almost every decade - particularly in the 1950s, 1960s, and early 1970s.

The additional outlet dredged at the north end of Lake Winnipeg allows up to 50 per cent more water to flow out of the lake. This enhanced outlet capacity has kept the level of Lake Winnipeg from getting as high as it would get under flood conditions in its natural state.

Manitoba Hydro cannot guarantee overland flooding will not occur on Lake Winnipeg, however due to the hydraulic differences between Lake Winnipeg and Lake Manitoba, Lake Winnipeg is not susceptible to the same magnitude of flooding, especially with the flood-relief benefits provided through Lake Winnipeg Regulation.

Answer: Yes, our current forecast has Lake Winnipeg's elevation at 714.6 feet by the end of July. Due to significantly increased precipitation over the past two months, we ramped up outflows through Jenpeg Control Structure starting June 1.

We continually monitor the timing and amount of water flowing into the lake from its many tributaries and adjust our operating plan for Jenpeg outflows based on this. If wetter conditions prevail, we will continue to adjust our operating plan by ramping up Jenpeg outflows further. If our forecast indicates the lake level will encroach on elevation 715, we will adjust Jenpeg outflows to the maximum discharge possible.

What the water level will be at the end of September is anybody's guess, as there are no reliable forecasts on how much rain will fall in the Lake Winnipeg watershed between now and the end of September. The current forecast indicates the peak Lake Winnipeg water level will be reached at the end of July, after which levels are expected to decline, which is on par with the normal hydrologic cycle for the lake.

Answer: Generally, Manitoba Infrastructure and Transportation has jurisdiction on Lake Winnipeg shoreline modifications. The issue of jurisdiction can be complicated though. The Province commissioned a report titled "Technical Report #4 Property Rights and Jurisdiction along the Shores of Lake Winnipeg", prepared for the Lake Winnipeg Shoreline Erosion Advisory Group in 2000. If interested, you may want to ask the Province for a copy of this report.

Answer: The key factor affecting Lake Winnipeg water levels are inflows to the lake from the many tributaries – the Winnipeg, Saskatchewan and Red Rivers etc. – which drain the 1,000,000 square kilometre watershed. There have been some dramatic precipitation swings in the watershed over the past year which have caused the lake level to rise to extreme highs early last summer, drop to slightly below average levels by this spring, and which currently are projected to cause the lake to rise to a peak of 714.6 by the first week of July, which is slightly above average for this time of year.

Note that there is no "maximum level" at which we are "legally allowed to regulate the lake level". Rather we have different operating parameters depending on the level of the lake – when the level rises above elevation 715, we are required to effect maximum discharge from the lake through our Jenpeg Control Structure in order to reduce the extent and duration of flooding on Lake Winnipeg. Precipitation records in the watershed indicate we have been in a prolonged wet period. There is no reliable way to determine when this will change and dryer conditions will prevail.

Manitoba Hydro monitors all inflows to the lake and attempts to regulate the outflow through Jenpeg in a manner to keep the level of the Lake below elevation 715. However, as witnessed last spring and early summer, inflows to the lake always have the potential to overwhelm the outflow capacity through Jenpeg and result in high lake levels.

Our monitoring system keeps us informed about the timing and amount of water flowing into the lake, and we continually adjust our operating plan for Jenpeg outflows based on this. In the current situation, we have increased outflows through Jenpeg to account for precipitation increases in the past two months – this will have the effect of reducing the amount of water level rise on Lake Winnipeg, but will still allow it to rise by a couple inches.

If wetter conditions prevail, we will continue to adjust our operating plan by ramping up Jenpeg outflows. This approach has kept the lake from reaching the extreme highs it did before regulation, while still maintaining the natural annual cycle of increasing water levels through the spring and summer, and decreasing water levels through the fall and winter. Similar to its natural state before regulation, when enough rainfall falls in its watershed, the level of Lake Winnipeg will rise.

Manitoba Hydro adheres to operating priorities, which include incorporating stakeholder values in the operating planning process – such as those of Lake Winnipeg residents and communities downstream on the Nelson River. Our staff are very aware of the stress high lake levels have caused in the past several years. Our system operators are under continual pressure to factor these sentiments into the Jenpeg operating plan, and the current plan for Jenpeg accounts for this.

Answer: We are not aware of any research indicating that Lake Winnipeg has gone dry in the past 2,000 years. We are familiar with the work the Geological Survey of Canada did in the 1990s which showed that the north and south basins only joined together to form present day Lake Winnipeg about 2,100 years ago. Their work was published as:

Todd, B.J. Forbes, D.L. Lewis, C.F.M., Matile, G.L.D., Nielsen, E. and Thorleifson, L.H. 1997: Geology of Lake Winnipeg: highlights of the Lake Winnipeg Project, 1994-1996. Geological Survey of Canada, Open File Report No. 3434

For the approximately 100 years of water level data we have for Lake Winnipeg, major droughts in the 1930s and early 40s produced a water level elevation of 709.5 feet above sea level (or about 4 feet lower than the average level). The average depth of Lake Winnipeg is 34 feet.

Answer: We agree with your comments concerning extreme high levels but not with your comments on extreme low levels. Since the Lake Winnipeg Regulation (LWR) project was constructed in 1976, the Lake Winnipeg watershed has not experienced the same extreme droughts like those from the 1930s and early 1940s (we refer to the 1939-1941 drought as the "drought of record"). Therefore we cannot say these same extreme low levels will not occur at some point in the future.

If you examine water levels in the 30–35 years before and after regulation (i.e. 1943 to 1976 vs. 1976 to 2012) you will note similar extreme low levels between the two periods. We have been looking at this issue and have recently completed an analysis comparing levels since regulation with what lake levels would have been like without the operation of the LWR. Preliminary results of this analysis indicate that during extended drought periods we have not affected the magnitude of extreme low levels (e.g. 1989 and 2003). This analysis will be presented as part of a Manitoba Hydro presentation at the Living Lakes Canada Conference May 22 and 23 in Winnipeg.

Note also that if there was a drought similar to the "drought of record", it is difficult to forecast if water levels would get as low as they did at that time, because the Water Power Act licence which governs our operation of LWR states that if the level of Lake Winnipeg goes below elevation 711, the Minister for Conservation and Water Stewardship determines outflows through LWR.

Answer: After speaking with Manitoba Hydro's Ice Studies group, there doesn't seem to be a system in place at Manitoba Hydro to track the duration of the ice season, at least not on a long-term, continuous, basis.

External studies have been done and documented in journal papers, etc. This is an example which considers Lake Winnipeg. This paper summarizes historic trends on freeze up and breakup days.

Answer: Unfortunately 1913 is the earliest year for hydrometric data on Lake Winnipeg. I am aware of earlier hydrometric data from the United States for their portion of the Red River going back to the 1880s, which may be of assistance. Note though that the Red River only currently accounts for about 11 per cent of the annual inflow to Lake Winnipeg.

I also understand there is other research, such as tree ring analysis used to provide a rough approximation of wet and dry years over the past several hundred year timeline in Southern Manitoba, however I have not compiled or reviewed this data so cannot comment further on it.

Answers:

1. You are correct in your observation that the decline in the level of Lake Winnipeg has changed. Record inflows to Lake Winnipeg in the early part of the summer dropped dramatically by the start of August, to the point in mid-September where net inflows were extremely low, due in part to evaporative losses. In early October, the level of the lake was below elevation 715, with forecasted inflows to the lake projected to remain low.
2. On October 6 we reduced outflows through Jenpeg. This operation avoided unnecessarily prolonging flooding conditions downstream of Lake Winnipeg. After ice conditions have developed at the outlet channels, outflows from Lake Winnipeg will be maximized through the winter.
3. Levels are expected to continue to decline through the winter and land at around 713.5 feet in the spring.

Answers:

1. Yes, similar to the flared spout on a coffee pot, the higher the level of the lake, the greater the outflow pouring out of it.
2. Actually inflows to the lake reached 220,000 cfs, however the maximum outflow was approximately 180,000 cfs. This occurred when the level of Lake Winnipeg was at its peak of 716.9 ft above sea level, and is the maximum recorded outflow since records were kept in 1913. The dams on the Nelson River are engineered to support much higher flows.
3. All Manitoba Hydro generating stations are designed to pass extreme flood flows much greater than we have recorded to date.
4. Outflows would not be an issue for our generating stations at virtually any lake level, however, as occurred this year, at maximum outflow communities downstream on the Nelson River such as Norway House, Cross Lake, Split Lake, and York Landing experience issues associated with high water flows and flooding. For instance, Cross Lake experienced the highest recorded water levels ever this year, attributable to the incremental amounts of water flowing out of Lake Winnipeg, made possible by the Lake Winnipeg Regulation project.
5. Given the scale of the project, the channels and channel improvements constructed as part of Lake Winnipeg Regulation were optimized to allow as much water as possible to flow out of Lake Winnipeg, which has significant flood alleviation benefits for Lake Winnipeg. As reported in a previous response, there are still many natural choke-points on the Nelson River that constrain water flows. If the scale of the project were increased, additional flood benefits on Lake Winnipeg could be achieved, however this would be at great economic, social, and environmental cost.
6. Maximum discharge depends on the level of Lake Winnipeg, so as the level of the lake changes, so does the "maximum discharge" value. Therefore, it is not possible to sustain a particular discharge amount. As referenced in the response to your question 5, unless all the natural chokepoints on the 90km stretch between Lake Winnipeg and the Jenpeg Control Structure were expanded, additional dredging on 2-Mile and 8-Mile channels would not increase outflows from the lake.
7. Refer to response to your question 6 that "maximum outflows" varies with lake level and, therefore, cannot be specified at a certain flow rate. The conditions of our licence currently specify that we must go to maximum discharge whenever the level is above elevation 715. This licence condition is specifically listed to provide flood relief for Lake Winnipeg.

Answer: The flow regime on the Burntwood River will not change as a result of the new Wuskwatim Generating Station, with flows typically between 20,000 cfs and 37,000 cfs expected at the Wuskwatim site. The three units in the Wuskwatim powerhouse can use up to 38,845 cfs for power production before spill is required.

Answer: There is a misconception that Manitoba Hydro regulates the level of Lake Winnipeg to an elevation of 715 ft. The lake level primarily responds to inflows from the various tributaries – the Winnipeg, Saskatchewan, Red and other rivers. These inflows often exceed the maximum amount of water that can flow out of the lake, causing the lake level to rise. Water is always flowing out of the lake, both through the unregulated East Channel of the Nelson River or through the regulated West Channel, where we have a control structure called Jenpeg.

Manitoba Hydro prefers to have the water flowing out of the lake to run through our turbines so it can be used to generate electricity. We are able to optimize the creation of electricity at all our generating stations along the Nelson River when the elevation of Lake Winnipeg is between elevation 711 and 715 feet.

However when the level of Lake Winnipeg exceeds 715 feet, we are required by licence to allow as much water as is physically possible to flow out of the lake – termed "maximum discharge". At maximum discharge, the amount of water flowing out of the Lake and down the Nelson River often exceeds the capacity of our generating stations and we have to route water through spillways where it is not used to generate electricity.

Earlier this summer, flows on the Saskatchewan River exceeded the capacity of the Grand Rapids Generating Station and had to be sent through the spillway. However, once the flows on the Saskatchewan River decreased to the point where they could be accommodated through the generation station, the spillway was closed.

When water levels on Lake Winnipeg are high, Cedar Lake at Grand Rapids can be used to store excess water and delay it flowing into Lake Winnipeg. However once Cedar Lake is full, the water needs to be released to Lake Winnipeg, which is what happened earlier this summer.

You are correct that the level of Lake Winnipeg is forecast to fall below elevation 715 in October. Manitoba Hydro's operational plan for Lake Winnipeg accounts for increased inflows from the Lake St. Martin emergency outlet. Before making any operating changes (such as reducing outflows at Jenpeg), Manitoba Hydro will consider all inflows and conditions in basins draining into Lake Winnipeg.

Answer: When we effect maximum discharge, we operate to lower the forebay (water level immediately upstream of the dam) to a point at which Jenpeg is no longer the hydraulic control point for Lake Winnipeg outflow. By lowering the forebay below this target level, the hydraulic control moves upstream to one of the natural choke points in the river channel - Saskatchewan Rapids, Manitou Rapids, Whiskey Jack Narrows, and shallow spots in Playgreen Lake. So, in effect, it's these natural constrictions in the river controlling outflows from Lake Winnipeg, rather than Jenpeg. To maximize energy production at the same time (but as a secondary objective) we'll generally run all available units at maximum discharge and then adjust spill flow to achieve this target forebay level.

Answer: We have recently begun posting close-to-real time data from all Manitoba Hydro and Water Survey of Canada (WSC) water level gauges in Manitoba including WSC's Lake Winnipeg gauges – see Hydrological Data.

This information mirrors data which has been available for a number of years from WSC for their gauging stations on Lake Winnipeg – see Environment Canada's Real-time Hydrometric Data.

Note that water levels are listed for specific gauge locations and therefore do not provide a wind-eliminated lake level on a real time basis. The station you are likely interested in is 05SB006 Lake Winnipeg at Gimli, which lists water level readings every 5 minutes for the last week and daily average water levels for the past 12 months by clicking on the appropriate tab.

You are correct that we provide 60-day water level forecasts of the wind-eliminated level of Lake Winnipeg and other water level information on our website. The water level crest on Lake Winnipeg can be viewed on the graphs linked from the top of the Water Level Forecasts page.

Please note that Manitoba Hydro is not involved with the drainage works under commission for Lake Manitoba.

Concerning the comment about increased revenue through high water levels on Lake Winnipeg: We are not able to generate increased revenue by keeping the level of Lake Winnipeg high as the terms of our licence require that we discharge the maximum amount of water possible through our Jenpeg Control Structure when the level of Lake Winnipeg exceeds 715 feet above sea level in order to provide flood relief for Lake Winnipeg. At this rate of discharge, the amount of water exceeds the capacity of our key generation facilities on the lower Nelson River. Therefore, instead of being able to pass the water through the turbines at these stations, the excess water has to instead be routed through our spillways without generating electricity, and is hence lost revenue.

Answer: We stopped printing updates in the newspapers once the Lake Winnipeg water elevation peaked in July. As of August 30, the outflow from Lake Winnipeg was 165,000 cubic feet per second (cfs). Inflows from all the tributaries into the lake have dropped significantly and are at 100,000 cfs, with the lake elevation at 716.5 feet above sea level (asl).

Our forecast indicates that with normal amounts of rainfall, the Lake Winnipeg water level will decrease below elevation 715 feet asl in mid-October. We do not normally provide flow information (inflows and outflows) for the hydro-electric system waterways for a couple of reasons:

1. The public's main interest on Lake Winnipeg is with respect to lake levels.
2. Flow information is commercially sensitive and can give our electric utility competitors an economic advantage in the marketplace (this is not the case in a flood situation where there are no water scarcity issues).

Answer: We have recently posted close-to-real-time Water Survey of Canada (WSC) Lake Winnipeg station levels on our Hydrological Data pages.

This information mirrors data for gauging stations on Lake Winnipeg, which has been available on the WSC website at Real-time Hydrometric Data. Note that water levels are listed for specific gauge locations and therefore do not provide a wind-eliminated lake level on a real time basis.

We also provide 60-day Lake Winnipeg monthly water level forecasts.

The inflows to Lake Winnipeg are decreasing. The lake has currently peaked at elevation 716.9 feet above sea level, and with normal precipitation is expected to fall below elevation 715 in the fall. Over the past several weeks we have published advisory notices on Lake Winnipeg water levels in the Winnipeg Free Press, Winnipeg Sun, Interlake Spectator, and Selkirk Journal/Record, and have included these updates on our website. We do not have the capacity to arrange for individual mailing lists, however any further notices/updates will be available at Lake Winnipeg Water Levels - Current Status.

Answer:

1. See Lake Winnipeg Regulation Components for information on the outlets. The current outflow of 180,000 cubic feet per second (cfs), which is 240% of normal for this time of year, is a record outflow for Lake Winnipeg since water flows were first measured in 1913.
   • 2-Mile Channel: A 2 mile long, 600 foot wide, 30 foot deep excavated channel. It creates a 2nd outlet for Lake Winnipeg.
   • 8-Mile Channel: An 8 mile long, 600 foot wide, 30 foot deep excavated channel. It uses Kiskittogisu Lake as additional flow path.
   • Ominawin Bypass Channel: A 1.4 mile long, 1000 foot wide, 30 foot deep excavated channel. It bypasses constriction between Playgreen Lake and Jenpeg.
   • Jenpeg Control Structure & Generating Station: A 5-bay spillway and 6-unit powerhouse. It regulates Nelson River (west channel) flow & generates electricity.
2. The only control is the Jenpeg Control Structure and Generating Station. The 3 channels – 2-Mile, 8-Mile, and the Ominawin Bypass – do not have any control mechanisms.
3. Additional spillways are not feasible for several reasons:
   • There are a number of natural constrictions on the Nelson River all the way to Hudson Bay which would have to be excavated (at great cost financially, environmentally, and socially for the 15,000 people living downstream).
   • All of the existing generating stations on the Nelson River are sized for a certain amount of water. These stations would have to be resized at great expense and would be oversized at anything less than a flood event.
4. The north basin is significantly larger than the south basin so it is appropriate to have more gauging stations in the north basin. Note that in 1999, the Province of Manitoba's Lake Winnipeg Shoreline Erosion Advisory Group hired Baird & Associates Coastal Engineers Ltd. of Ottawa to perform an independent third-party assessment of Manitoba Hydro's water level determinations and reporting for Lake Winnipeg. Their report to the Advisory Group indicates that based on their analyses, there are no significant irregularities in how the water level information is being determined and reported. They did point out that the current water level gauge locations introduce a slight bias toward the south basin because of the larger number of water level gauges per surface area of the lake in the south basin.
5. See the chart Lake Winnipeg Monthly Mean Levels. Whenever the wind eliminated level is above 715 feet above sea level, Manitoba Hydro is required by licence to go to maximum discharge. Note that we will ramp up discharge if a forecast indicates this level will be reached in an attempt to avoid going over this level; once we go over the level we have no control over discharge and cannot optimize water flows for power production purposes. The wind eliminated level, which is a composite of all 8 stations, is used for water management purposes.

   The graph 8-Foot Difference North to South demonstrates how wildly water levels can fluctuate at the 8 stations and why the wind eliminated level is used.

Answer: The response to your first question is approximately 5 feet (excluding wave height). The previous recorded maximum was about 3.5 feet. This chart shows the levels recorded at the 8 water level gauging stations around Lake Winnipeg during last October's storm:

• Lake Winnipeg Elevation Oct.21–Nov.2, 2010.

To answer your second question, these 2 files are scans from the "Lake Winnipeg Shoreline Erosion Advisory Group Final Report in 2000" which show historical data on wind setups (excluding waves):

• Maximum Wind Setup Events, Winnipeg Beach/Gimli list.
• Maximum Wind Setup Events, Winnipeg Beach/Gimli bar graph.

Answer: We do have an operational model of Lake Winnipeg with the Lake Winnipeg Regulation (LWR) components in place (3 channels and Jenpeg control structure); however there is not a model to predict the level of Lake Winnipeg without LWR. I understand Manitoba Water Stewardship is looking at having an independent study on the water level effects of LWR as part of the final licensing process, so such a model may be part of this upcoming provincial initiative.

There would be a number of complicating assumptions to make in attempting to calculate what level the lake would be since 1976. The main assumption would be the winter ice conditions for each year since regulation. The problem with winter conditions is that the river downstream of Lake Winnipeg prior to LWR was susceptible to ice dams forming which would greatly reduce Lake Winnipeg outflow. However, ice damming is not certain to happen every year and the severity would need to be assumed.

Note we were able to calculate a with, and without, Lake Winnipeg Regulation calculation based on our operating at maximum discharge since July 1, 2010, when the lake was approximately 714.9 feet. Assuming the same July 1 starting level, the lake would have risen to more than 717.25 feet since July 1 had LWR not been in place - this is more than 1.25 feet higher than the current level.

Answer: I am not familiar with the rate of isostatic rebound specific to the north basin, however according to Todd et al. 1997 (reference below), since glacial Lake Agassiz receded, "for most of the Lake Winnipeg basin, the changes in relative elevation has been tens of metres ranging up to 50 m in the south".

Todd, B.J.; Forbes, D.L.; Lewis, C.F.M.; Matile, G.L.D.; Nielsen, E.; Thorleifson, L.H. 1997: Geology of Lake Winnipeg: highlights of the Lake Winnipeg Project, 1994-1996. Geological Survey of Canada, Open File Report No. 3434.

Answer: Of the 6 turbines which required shaft repairs, 4 have been completed while the remaining 2 are scheduled to be back in service in February and March (one each month). The turbine repairs did not have a significant effect on our ability to pass water through the station as water was diverted through the generating station spillway. Initially, when all 6 turbines were out of service for repairs, it caused a reduction of approximately 5 per cent (or about 200 cubic metres per second) to Lake Winnipeg total discharge. All 6 turbines were out of service from June 26, 2010 to August 23, 2010, when the first turbine repair was completed.

The Jenpeg Generating Station has been at maximum discharge since July 1, 2010 and is currently passing about 97,000 cubic feet per second. At mid-January 2010, the GS was also at maximum discharge of about 87,000 cfs. The difference in outflow capacity is due to a combination of higher Lake Winnipeg water levels and an exceptional ice cover formation this year, which has allowed us to pass more water than is the case for most years.

Answer: Current research has not determined if regulation of Lake Winnipeg between the levels of 711 to 715 has a discernable effect on blue-green algae formation. The regulated 4-foot range is within the natural range of fluctuations for the lake, and the average level of the lake for all times of the year is very close (within 1/10 of a foot) to the natural, unregulated, average level of 713.4 feet. The Lake Winnipeg Research Consortium (LWRC) is conducting research into the factors affecting algae formation. Manitoba Hydro is a financial supporter of the LWRC.

Answer: While Lake Winnipeg water levels reached similar high levels in the past 2 years, you are correct that last year's level at the end of January was much lower than what it is forecast to be at the end of January 2011. The reasons for the difference is the timing of the peak levels, and the amount of inflow to the lake.

In 2009, the lake level peaked at approximately 715.5 in mid-July and over 6 months later (at the end of January) without any further major inflows to the lake, it was approximately 1.8 feet lower. Conversely, this year, high inflows came much later in the year and Lake Winnipeg peaked 2 months later at approximately 715.6 ft in mid-September, and then a secondary peak occurred November 1st, following the major storm at the end of October. As well, inflows into the lake this year were sustained at a high level for a much longer period than in 2009.

Although Lake Winnipeg Regulation increases the outflows from the lake by 40-50 per cent over a state of nature, if the inflows from the lake's tributaries (Saskatchewan River, Winnipeg River, Red River, etc.) exceed the outflow capacity, water levels will rise. That is what happened this year. Throughout the summer months, inflows exceeded outflows even though we were releasing the maximum amount of outflow from the lake.

Similar to last year, we are at maximum discharge through our Jenpeg control structure and plan to be there over the remainder of the winter. We are currently forecast to be at level 714.99 on January 5, 2011. However, as ice cover has only recently formed in the area of the outflow, this forecast may be revised once further information is available.

The wet period over the past 7 years may make it seem as if there's a policy to keep the level of Lake Winnipeg close to elevation 715, however the level is directly attributable to the amount of precipitation in the drainage basin. We are allowing the maximum amount of water out of the lake as is physically possible through our system, so there is nothing more that can be done to bring the level of the lake lower.

Climate change is being studied at Manitoba Hydro, however the wet period currently being experienced is not a new phenomenon - over the course of our water level records for Lake Winnipeg back to 1913, many wet cycles are evident, as are dry cycles. Our water management practices account for the full range of water conditions.

The hydroelectric system operations take into consideration a number of complicating factors – Water Power Act Licences, Manitoba's electrical loads, export markets, effects on downstream communities and resource user groups, ice conditions, inflows and outflows, physical waterflow constraints – which dictate water management decisions.

Answer: Current water level information is available on the Water Surveys of Canada website. Note that water levels are listed for specific gauge locations and therefore do not provide a wind-eliminated lake level on a real time basis.

Manitoba Hydro posts forecasted Lake Winnipeg levels.