HYDROGEOLOGY IN THE LITTLE CHAZY RIVER WATERSHED, NORTHEASTERN NEW YORK: CLUES TO THE FAILURE OF MINER DAM

Miner Dam was built in the upper Little Chazy River watershed between 1910 and 1913 to provide hydroelectric power to rural communities in northeastern Clinton County, NY. The dam was plagued by poor hydrogeological site conditions from its inception, which coupled with mechanical problems at the power station, ultimately forced abandonment of the project in 1922. A 12 ha vestigial reservoir presently occupies 60,000 cubic meters of the former reservoir basin.

Surface water and atmospheric inputs and outputs and changes in reservoir storage were carefully monitored between 15 June and 22 November 2000 to produce a hydrologic budget for the reservoir behind the dam. The reservoir’s water budget was dominated by surface water flow, with stream outflow generally exceeding inflow, throughout the summer. This condition was maintained by positive groundwater flux and non-channelized overland storm flow and springs on the southwestern flank of the reservoir. Stream flow reached its seasonal low in September and October. Stream inflow to the reservoir exceeded outflow during this period, corresponding to lowering of the potentiometric surface and cessation of non-channelized inflow. Net groundwater flux in the reservoir was estimated by budget analysis during periods when non-channelized inflow was negligible. These estimates indicate that approximately 50% of the inflow to the reservoir was lost to groundwater seepage during low flow conditions. Groundwater influx was reestablished with recharge in early November. Seepage losses and inadequate late summer and fall stream flow account for most of the hydrological problems associated with Miner Dam.