Tuesday, April 29, 2014

Dakota County will begin refill of Lake Byllesby reservoir May 15

The Dakota County Environmental Resources Department plans to refill the Lake Byllesby reservoir to its summer elevation beginning Thursday, May 15.


In the fall, the reservoir level is lowered 3 feet to 853.7 feet, and remains there until May 15 when refilling to the summer elevation of 856.7 feet is permitted to start. The Minnesota Department of Natural Resources sets these seasonal lake levels to make it easier for farmers to get into their lower-lying fields in the spring, and to offer residents the opportunity to enjoy water-related recreational opportunities in the summer. 


Spillway construction activities will not affect the pool refill.


Refilling the reservoir is done by raising 41 trip gates located at the top of Lake Byllesby Dam. Up to 20 percent of the water flowing from the Cannon River into the reservoir is captured to fill the pool. The remaining 80 percent of inflow is released downstream through the turbines and crest gates.


To ensure adequate flow downstream, the reservoir cannot be refilled if the flow of the river, as measured in Welch, drops below 50 percent of the normal water-flow levels.


Raising the Lake Byllesby reservoir level requires Dakota County employees to access the top of the spillway and manually lift and set the trip gates. This is only possible when there is little or no water flowing over the spillway. In the event that it is not possible to raise the gates May 15, the gates will be raised at the earliest possible date thereafter.


Access weather data at the Byllesby Dam and lake level information generated from river gages at www.byllesbydam.org. For information about the refill process, call the Dakota County Environmental Resources Department at 952-891-7000.

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