Willow Valley Reservoir (Klamath)

Reachcode: 18010204002588 | Area: 543.8 acres | Shoreline: 6.9 mi | View on Interactive Map

(From Atlas of Oregon Lakes, Johnson et al. 1985). Willow Valley Reservoir is a relatively large irrigation reservoir just north of the California border in the southeast portion of the Klamath Basin. In spite of its primary purpose of storing water for downstream irrigation, it has become well known locally for its outstanding bass fishing. Largemouth bass taken here are reported to average better than a foot long, some weighing as much as four pounds.

The reservoir was constructed about 1920 with a dam across the East Branch of Lost River and it collects the drainage from an area of about 59 square miles of high semi-arid rangeland. Most of the land in this area is administered by the Bureau of Land Management and is open to the public. No camping facilities are available at the reservoir.

Water in the reservoir contains concentrations of major ions that are typical for eastern Oregon reservoirs; pH is slightly higher than neutral. The water column develops thermal stratification in summer and there is some oxygen depletion in the deeper water. Chlorophyl concentration is above average, and phosphorus concentration is well above average. Transparency is limited due to the presence of planktonic algae and suspended sediment. A bloom of Melosira granulata was observed on 7/7/82 as well as the blue-green alga Anabaena spiroides and the flagellate Ceratium hirundinella. Very little macrophyte growth is found, possibly because of the poor transparency.  By all indications, Willow Valley Reservoir is distinctly eutrophic.