Platt 1 Reservoir (Douglas)

Reachcode: 17100301005061 | Area: 127.1 acres | Shoreline: 2.8 mi | View on Interactive Map

(From Atlas of Oregon Lakes, Johnson et al. 1985)  Platt I Reservoir was built for flood control and irrigation supply in the late 1960s. It consists of a 33-foot high earthfill dam which impounds the waters of Sutherlin Creek and tributaries. It is exceptionally shallow with a maximum depth of only slightly over 12 feet at full pool; over half the reservoir is shallower than five feet. Water levels drop during the summer and stay quite low in the winter. As a result cattails and other emergent macrophytes encroach upon the water, covering nearly half the surface. Most of the rest of the bottom is covered with submerged macrophytes.

The contributing drainage basin is primarily private land with much of it in use as pasture and farm land. There are some patches administered by the Bureau of Land Management. The shoreline of the reservoir is entirely in private ownership, although public access is permitted and one paved boat ramp is available. It has become an excellent fishing spot and is open year round. Rainbow trout, crappies, bluegill, largemouth bass, and catfish make up the catch.

The reservoir is too shallow to develop a distinct temperature stratification and the water becomes quite warm in the summer. The concentrations of major ions in the water are exceptionally high. Except for coastal lakes and a few lakes in the Basin and Range area of south-central Oregon, Platt I Reservoir is one of the saltiest in the state. The source of these ions is unidentified, but the high concentration appears to be characteristic of waters in the area; nearby Cooper Creek Reservoir is also saltier than is typical. Concentrations of chlorophyl and phosphorus, as well as water transparency, are average and indicate mesotrophic conditions.