Spring Dam Drawdown Info -  

(always the last weekend in April that contains a Saturday and a Sunday - dates for 2018 are April 28-29)

Rate of drawdown and refill is approximately 24 inches per day, (1-2 inches/hour).  The impoundment is expected to be refilled by end of day Tuesday, however, this will depend on the inflow rates at that time.

Thursday - Friday:  Dewatering period; the discharge from the dam is increased by approx. 300-500 cfs.
Friday - Sunday:  Maintain run-of-river flows at lowered impoundment elevation. 
Sunday Night - Tuesday:   Refill period; the dam maintains a discharge downstream of 150-250 cfs based on current river flow rates.
Tuesday afternoon or evening: Return to run-of-river flows at normal impoundment elevation.

During certain years, due to flooding, the drawdown has been cancelled. The volume of water that would be required to accomplish a drawdown would have resulted in significant stress to the dam, erosion north of the dam, and raised water levels on the Grand River, which could cause flood damage to property on the Grand. In addition, operators at our dam needed time to assess our dam's condition. 

There are two watersheds that potentially affect us, one, the rain that falls in the Grand River watershed to the east and two, the rain that falls in our Thornapple River watershed to the south and then east.

The danger of both watersheds receiving a lot of rain is that the Grand River backs up into the Thornapple River when it floods because the mouth of the Thornapple is so close to our Ada dam. In 1904, the Grand River was so high that the entire Ada Park and the building that houses Georgie's resale stood in four feet of water, and Thornapple River drive was flooded. News media portrayed the 2013 flood as one of the largest. It was not. Several floods have exceeded the 2013 volume in the past 100 or more years. The 1904 flood covered the entire area around our dam, with only the railroad track above water. Photos are avaialable at the Ada Historic Museum. Water covered the area north of Thornapple (toward Amway) in Ada Village.

When the Grand River floods, it slows the outflow of water from our river, and our river backs up. If our watershed receives a lot of rain at the same time as the Grand River watershed, that could create significant flooding. Members can get instructions about how to receive text alerts of rising water on our website by clicking on the "Frequently asked questions."

Normal water levels are about 4 feet at the Caledonia monitor. The Cascade dam does nothing more than maintain a constant level and let the water that comes down the river pass through, as much as possible. The same is true of the Ada dam. The operators of our Ada dam are required by court order and federal rules to operate the dam to attempt to maintain a specific level, as well as to allow water to run naturally down the watershed. Thus, the operation of our dam has no purposeful bearing on height of water, flow of water, or the erosion or lack thereof between our dam and the Grand River, since we are required to allow the naturally flowing and constantly changing river volume to pass through. Water is first channeled through the turbine tubes, then spill gates are opened as required by the volume of water approaching the dam. It is the volume of water that  causes erosion; the dam merely allows water to flow through.  The operation of the spill gates merely is a response to large volumes of water. The Caledonia Dam is manually operated and tends to have more variation in water flow than either Cascade or Ada. That is why it seems we get "waves" of water quickly rising and then dropping. Those are not due to the operation of the Cascade or Ada dams but are the result of what comes down the river. The Caledonia guage is two hours upstream from the Cascade dam, so you can monitor this guage and know what is coming two hours ahead.

Members should understand that the dams cannot stop or even slow high water flows. If the water volume exceeds the capacity of the four spill gates, the water would flow over and around the dam.  The dam operators cannot let "extra" water flow through the dam to lower our impoundment in anticipation of approaching flood waters. That would violate the federal rules. Also, flood levels often persist for days, or weeks, so lowering the water levels a few hours ahead of approaching flood waters would have only temporary effect.