Woahink Lake is located on the central Oregon coast south of the city of Florence and about three miles inland from the Pacific Ocean. Its southern end lies adjacent to US Highway 101, so that it is seen by all travelers on this major arterial. The lake basin owes its origin to the fluctuations in sea level that accompanied the latter stages of the Pleistocene Epoch, alternating periods of submergence and emergence of the coastal zone (Cooper 1958). During periods of submergence, the mouths of coastal streams were inundated by the higher water level. Many small streams lacked the erosive ability to prevent the obstruction of their mouths by sediment impoundments. Woahink Lake, lying on a marine terrace, was formed in this manner. The stream system that was inundated to form the lake basin was probably a tributary of the ancestral Siltcoos River. The 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. Thus, the Woahink Lake basin is a deep, steep-walled cryptodepression.

Woahink Lake exhibits the characteristic dendritic, or branching, pattern of an impounded water body, whether it be an artificial impoundment or natural. Three large, partially isolated arms are fed by tributaries 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 through the Woahink Creek outlet. The total drainage basin is only 7.4 miles in area, 16.6 percent of it covered by the lake itself. Thus the hydrologic retention time is relatively long. The small drainage basin is, for the most part, covered with a coniferous forest and receives approximately 80 inches of precipitation annually. Adjoining the lake on the west side is a series of dune complexes, including a large active dune to the southwest which is very apparent along the west side of the highway. This area is within the Oregon Dunes National Recreation Area. The eastern shoreline abuts the foothills of the Coast Range. Most of the basin consists of privately owned land and about 85 percent of the shoreline is also in private ownership. A number of lakefront residences, including both summer cabins and permanent dwellings, are located on the shoreline, most of them on the eastern side which is interlaced with a network of local roads. Most of these homes have been constructed since 1960 and some are on septic tanks and drainfields.

The remainder of the shoreline, about 15 percent of the length along the northwest side, is within the Jessie C. Honeyman State Park. This is a 522 acre park which is an excellent nature sanctuary despite the large amount of development for recreational purposes. Dense growths of shrubs, three small lakes, the beach, and the forest provide food and habitat for a great variety of birds and mammals. A nationally endangered species of pitcher plant (Darlingtonia californica) grows in the bog area within the park, and mixes with other typical bog species, such as sedges and water lilies. The bog's water supply is maintained by several small creeks entering from the north and by a naturally high water table. The Nature Conservancy has identified the bog as a critical natural area in need of protection. Darlingtonia is now protected only in the Darlingtonia Botanical Wayside, and the pitcher plant will not last long as a species if this protected site remains as small as it is. A larger bog is needed to provide sufficient buffer for the population.

Honeyman State Park has long been extremely popular for outdoor recreation. Straddling the highway, the park essentially consists of two components – one adjoining Cleawox lake, the other adjoining Woahink Lake. At Woahink Lake there is a large picnic area in a lovely setting on the north shore. Two paved boat launches and a swimming area are available to visitors, and there is a large campground located west of the highway south of Cleawox Lake. Several species of fish are found in the lake, including warm–water species such as yellow perch and largemouth bass, and cold water species such as rainbow trout, cutthroat trout, and kokanee. Some anadromous salmonids also enter the lake from Siltcoos Lake.

Woahink Lake is a warm, monomictic type by virtue of its single yearly mixing period which occurs in the winter. At that time water temperatures at any depth are never less than 39 degrees Fahrenheit (4 degrees Celsius). In addition, the lake is stratified in the summer. Bottom material consists of muck in the deeper areas and mostly sand and gravel in the littoral areas. Macrophytes are present only in low numbers and in the shallow ends of the arms; they are not a problem here as they are in so many other coastal lakes. The predominant macrophyte species is Myriophyllum. Water quality in the lake is very good

The above average mean depth of Woahink Lake (32.6 feet) makes it somewhat less susceptible to adverse cultural impacts than many other coastal lakes in Oregon (Larson 1970). Nevertheless, its current oligotrophic status and popularity with many users make it particularly vulnerable to cultural eutrophication. Also, several land development projects have denuded large areas that adjoin the lake, generating exposed and unconsolidated material, much of which has eroded and washed into the water. Continued development will aggravate this problem of bank erosion. The control of future impacts on the quality of water in Woahink Lake is important for many reasons, not the least of which is that water for years has been pumped without treatment from the lake for drinking and domestic purposes. Any degradation in water quality would impair its use for this purpose, and would also impair enjoyment of the lake for recreation.

References:

Cooper, W. S. 1958. Coastal sand dunes of Oregon and Washington. N.Y. Geol. Soc. Am. Memoir 72. New York, NY. 169 pp.

Johnson, Daniel M., R. Petersen, D. Lycan, J. Sweet, M. Neuhause, A. Schaedel. 1985. Atlas of Oregon Lakes. Oregon State University Press. 318 pages.

Larson, D. W. 1970. Limnological studies on the Oregon coast. 1. Woahink Lake. WRRI-3. Water Resources Research Institute, Oregon State University, Corvallis OR. 40 pp.