Hydrologic investigation of the Ophir Creek watershed near Yakutat, Alaska

Abstract

Data on streamflow and ground-water levels were collected in the Ophir Creek watershed in southeast Alaska to obtain information about the relations between streamflow, ground-water levels, and precipitation. In addition, the possible effect of an experimental channel excavation to increase flows in Ophir Creek was evaluated. Stream discharges were monitored continuously at one site and measured intermittently at five other sites from October 1991 to May 1997, and ground-water levels were measured weekly in seven wells from July 1995 to October 1996. All measured ground-water levels were less than 11.4 feet below land surface. The data indicate that ground-water levels are closely related to rain and snowmelt, which in turn are related to water levels in Ophir Creek. Six of seven wells had peak water levels concurrent with peak flows in Ophir Creek. In one well, both maximum and minimum water levels coincided with maximum and minimum streamflow in Ophir Creek. Deepening part of the Ophir Creek channel by excavation has increased streamflows along the deepened reach; however, some of this additional flow infiltrates into the stream channel downstream from the excavated reach. The deepened reach flowed intermittently before the excavation and continues to dewater during prolonged periods of no precipitation.