Low flow in the Rock River and low water levels on Lake Koshkonong

As many have noticed, the water levels in the Rock River and on Lake Koshkonong have been very low since the winter drawdown began in October.  

The reason for this is that the discharge in the Rock River is very low, due to the lingering effects of the drought of 2012.  

With the discharge this low, the slide gates and wicket gates at Indianford dam have the capacity to come close to achieving the drawdown water level that is specified in the DNR operating order for the dam, which is gage height 5.0 on the USGS Lake Koshkonong Gage.  In most years, discharge in the Rock River is high enough so that even with all the Indianford dam gates open all of the time, the Lake Koshkonong water level seldom gets below gage height 6.0.

For example, over the past 30 days, the discharge in the Rock River at Newville has declined from approximately 1000 cubic feet per second to the discharge recorded for today, approximately 550 cubic feet per second.  

The median flow in the river is typically over 1000 cubic feet per second for this entire time period.  With all of the gates open at the dam, Lake Koshkonong water levels have declined from gage height 6.0 to 5.1.  The current lake level is still approximately 0.1 feet above the winter operating order specified elevation.

The current water levels are in conformance with the operating orders for the dam – what’s unusual is that the discharge in the Rock River is so low that the district is able achieve compliance with the order.