General Watershed Information

All of the gauges located throughout the basin are owned and operated by various Canadian and U.S. federal agencies, including Environment Canada, the United States Geological Survey, and the Canadian Lake of the Woods Control board.

Data Collection

The level of Rainy Lake is measured at Environment Canada gauges located east of Fort Frances, at the "Five Mile Dock" and at "Bears Pass". The level of Namakan Lake is measured at an Environment Canada gauge upstream of the International Dam at Kettle Falls.

In addition to the data collected by the network of gauges, AbitibiBowater Inc. and Boise Inc. also access the Monthly and Seasonal Outlook from the U.S. National Weather Service, which provides general trends, and the Ontario Hydro Snow Survey, which provides measurements in the early spring of the depth and moisture content of the snow cover in the watershed.

Precipitation data alone is not a good indicator of predicting inflow into the lakes and must be coupled with other factors to change the discharges from the dams. Some of the reasons for this are that precipitation can be very localized and not represent conditions over large areas of the watershed. Because of the size of the lakes, precipitation over a few hours or days may not impact lake levels.

Typically only one-third of the spring run-off is from snowmelt, while two-thirds is directly from the amount of rainfall during April, May and June.

Frost in the Ground

The extent of the frost in the ground in the early spring affects the rate of infiltration of precipitation and/or snowmelt and therefore influences the magnitude of the runoff into the lakes.

Ground water saturation

After prolonged periods of rainfall the ground becomes saturated and increases the amount of water that will enter the lakes from subsequent rains.

Evaporation

Evaporation from the lake surfaces and from the surrounding land is significant and variable. It is estimated that on average about two feet of lake level is lost directly to the atmosphere each year due to evaporation from the lake surfaces. More than .4 inches or one centimeter can be lost to evaporation on a warm, windy day in August, and at times the volume of water lost can actually exceed the lake inflows during that period.

Wind effects

Wind causes the lake surface to "tilt" slighty and complicates the determination of the true overall average lake level. It is believed that a moderate wind from the west can raise the lake level at the east end of the Rainy Lake by two inches or five centimeters or vice versa if the wind is from the east. This can affect the calculation of inflow, which in turn is used to calculate outflow decisions.

Downstream effects

Rapid, large changes in outflow from Rainy Lake cause swings in the water levels of Rainy River downstream of the dam. This situation can be magnified by increased flows entering the river from the Littlefork, Bigfork, Black and Rapid rivers. Late winter flow changes can be a problem for the ice fisherman in the Birchdale area. Summertime changes can be a problem for boat and plane owners upstream of the dam especially if the changes include spillway gate openings or closings.

AbitibiBowater operates a toll-free phone line from early spring to late fall to provide the public with information on water levels for Rainy and Namakan Lakes. This Lake Level Information Line includes daily recorded messages with information on lake elevations and outflows for Rainy and Namakan Lakes, precipitation levels and spillway gate operations for the dams at International Falls/Fort Frances and Kettle Falls. Call 1.800.509.LAKE or 1.800.509.5253.

In addition to this toll-free number, lake level graphs for Rainy and Namakan Lakes are published weekly in the Fort Frances Times and International Falls Daily Journal.

AbitibiBowater Inc., Fort Frances, Ontario

   Marc Mantha
   Phone: 905.438.8539, ext: 203

Boise Inc., International Falls, Minnesota

   Bob Anderson
   Phone: 218.285.5312

   Jay Lofgren
   Phone: 218.285.5218