Obenchain Reservoir (Klamath)

Reachcode: 18010202003345 | Area: 71.3 acres | Shoreline: 1.6 mi | View on Interactive Map

(From Atlas of Oregon Lakes, Johnson et al. 1985)  Obenchain Reservoir is a small water impoundment which, in conjunction with several other similar facilities, helps to maintain agricultural production in this semi-arid region of South Central Oregon. The reservoir was constructed in the early 1950s with a 26-foot high, earthfill dam on Fritz Creek. A second dam was necessary to impound a sufficient amount of water in this area of low relief. Inflow to the reservoir is intermittent and the water level fluctuates considerably because of irrigation withdrawals. According to local residents it dries up completely in some years. Although located within the boundaries of the Fremont National Forest, Obenchain Reservoir is on private land and is privately owned and operated. There are no recreational facilities and no boat launching facilities. Nevertheless, there is a well used camp spot at the south end of the lake and local residents frequently fish the lake from the shore and from small boats.

The reservoir is relatively shallow (mean depth = 5 ft), reaching a maximum depth of only 18 feet. The concentrations of ions and the conductivity are about average for eastern Oregon reservoirs and the pH is sometimes well above average (8.5 or more). The concentration of phosphorus is high, but water transparency is better than average (13.0 feet; 4.0 meters). Macrophytes grow over a large portion of the bottom and are responsible for most of the primary production in Obenchain Reservoir; the populations of phytoplankton are not high. An oxygen deficit develops near the bottom at depths greater than 16 feet. Due to this combination of characteristics, particularly the high biological productivity, the reservoir is classified at the higher end of mesotrophy.