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Woahink Lake is a large, deep, clear lake located about three miles inland from the central Oregon coast, directly south of the city of Florence. The lake is popular for boating, swimming and fishing. Fish species include yellow perch, largemouth bass, rainbow trout, cutthroat trout, kokanee, and coho salmon. Woahink Lake’s primary recreational access is through Jessie C. Honeyman State Park. This 522-acre park covers about 15 percent of the lake' shoreline and contains developed recreational areas and natural areas. An endangered species of pitcher plant (Darlingtonia californica) grows in the bog areas within the park. Much of the remainder consists of private lakeside residences.
The lake basin owes its origin to the periods of submergence and emergence of the coastal zone that accompanied the latter stages of the Pleistocene Epoch (Cooper 1958). During periods of submergence, coastal streams were inundated by the higher sea level. Subsequent migration of sand dunes across the mouths of the streams as ocean levels decreased created impoundments. The current water surface of Woahink Lake is 38 feet above mean sea level, and the bottom at its deepest point is 74 feet deep, or about 36 feet below sea level, the lowest of any of the sand-dune dammed lakes on the Oregon coast. Tributaries feed three large arms from the north and east; the longest of the three is only about three miles in length. The lake empties southward into adjacent Siltcoos Lake via Woahink Creek.
Woahink Lake’s watershed is 1784 hectares with 16.8 percent covered by the lake itself. More than half of the watershed is covered with conifer and hardwood forests. The eastern shoreline of the lake abuts the forested foothills of the Coast Range. The remainder consists of residential areas within the City of Dunes City, non-forested vegetation, and a small percentage of sand dunes and urban areas. The sand dunes in the watershed are the edge of a large active dune area to the southwest within the Oregon Dunes National Recreation Area. Urban areas within the watershed are located along highway 101, a major north south arterial. Road density is similar to that of other watersheds near the central Oregon coast. Average precipitation, nearly 80 inches per year, is typical of the Oregon coast area.
Woahink Lake exhibits the characteristic dendritic, or branching, pattern of an impounded water body. The southern half of the lake is has large areas deeper than 15 meters. The deepest point measured in the lake during the summer of 2000 was 22.8 meters. The northern portion of the lake consists of three relatively shallow arms with extensive areas less than ten meters deep. The mean depth for the entire lake is 11.4 meters.
Warm temperatures and strong winds keep Woahink Lake's surface layer mixed down to approximately 10 m during the summer. Since the lake does not freeze over during the winter, the lake is well mixed from the Fall through Spring.
Water quality data has been regularly collected by the City of Dunes City since the early 1990's and others. Secchi disc transparency, chlorophyll a concentrations, and total phosphorus concentrations indicate that the lake has been consistenly oligotrophic to mesotrophic. Hypolimnetic oxygen depletion has also been noted.
Macrophytes are present in low densities in shallow portions of the lake. Parrotfeather (Myriophyllum aquaticum) and Elodea canadensis are two abundant non-native invasive species. Other species present include Brasenia shcreberi, Nuphar polysepala, Nymphaea odorata, Valisineria americana, Utricularia vulgaris, Utricularia spp., Potamogeton spp., Myriophyllum spp., Scirpus spp., Isoetes spp., Najas spp., Chara spp., and Juncus supiniformis.
Although the water quality of Woahink Lake appears to be in good shape, there are concerns that further development of the watershed and the introduction of non-native invasive species pose significant threats.