The Lake O’ the Hills dam is privately owned dam that impounds a recreational lake. When the State of Alaska Dam Safety Program determined the existing corrugated metal pipe spillway was no longer fit for service due to insufficient capacity and pipe corrosion, NGE-TFT was contracted to design and construct a new spillway. Because the spillway was the only outlet for the reservoir, water levels were maintained during construction using a 6-in diameter siphon. A sheet pile weir and rip-rap protected spillway was designed to pass a flood flow of approximately 250cfs.