Annual Lake Lowering

Grand Lake Rule Curve Chart

In 1992, the Federal Energy Regulatory Commission (FERC) issued the Grand River Dam Authority a new license to operate the Pensacola Dam and Grand Lake. In 1996, an amendment to that license required GRDA to begin holding Grand Lake at different elevations throughout the year.

In early August, this license requires GRDA to begin lowering the elevation of Grand Lake to meet a 741’ mark by September 1. The lake is then held at this elevation until mid-October, when GRDA is required to begin raising the elevation to 742’ by month’s end. The license then calls for the lake to be held at 742’ through the winter and spring months, before GRDA begins raising it to meet a 744’ mark on June 1. It is then held at this elevation again, until August 1.

The accompanying graphics illustrate the elevation requirements and schedule mandated by GRDA’s operating license for Pensacola Dam/Grand Lake, as issued by FERC.