Clear Lake (Lane)
Reachcode: 17100206000579 | Area: 152.8 acres | Shoreline: 2.5 mi | View on Interactive Map
(From Atlas of Oregon Lakes, Johnson et al. 1985). Clear Lake is one of a string of lakes on the central Oregon coast that lies on the 50-mile long North Florence dunal aquifer, an important groundwater body supplying water for domestic needs in the Florence area. The Heceta Water District withdraws directly from Clear Lake, an unfiltered domestic source of water that will require special protection for this use to continue. There is no public road to the lake, the only access being a one mile hike across extensive sand dunes. In spite of this limited access, some people do tow motorboats across the dunes and launch them on hard sand boat ramps.
The geologic origin of all the lakes in this group (Collard Lake, Clear Lake, Ackerly Lake and Munsel Lake) can be explained simultaneously. The dunal aquifer is an accumulation of aeolian (wind blown) sand that rests on an ancient wave cut terrace. This terrace can be seen at 50 to 150 feet above sea level along the coast to the north near Newport, and to the south near Bandon and Port Orford. However, along the coastal stretch from Coos Bay to Heceta Head the terrace has been warped downward below sea level and an extensive accumulation of sand deposited on it. This dunal sheet is of fairly recent geological origin. Carbon-14 dating of woody material deposited at the base of the sand and on top of the terrace clays showed that it originated about 27,000 years before present (Schlicker and Newcomb 1974). The dune sheet is broad and relatively flat and is composed of successive layers of sand that were built up as deflation plains behind eastward migrating sand dunes. The remnants of those dunes that have become stabilized and those which have not are the major topographic features on the dunal sheet surface. Clear Lake and others in this string lie along the eastern margin of the dune sheet, between the buildup of the dunal sheet to the west and next to impermeable bedrock to the east. As the migrating dunes approach the hills the wind loses its ability to transport sand and the largest portion of the sand remains to the west, thus leaving a depression or series of troughs along the base of the hills. Collard, Clear and Munsel Lakes are thus due to marginal ponding by dune masses, a mode of formation typical of many other lakes on the Oregon coast (Cooper 1958).
The sands of the North Florence Aquifer are a substantial water holding and transporting system. Permeability is high as indicated by a lack of streams originating on the sands, in spite of over 60 inches of annual precipitation. Most of the water percolates into the sand and discharges directly to the ocean. The only surface streams that cross the dune sheet, Sutton Creek to the north and the Siuslaw River to the south, derive most of their flow from the hills to the east; there is also substantial discharge of groundwater into these streams from the aquifer. The primary internal surface drainage system begins near Collard Lake and flows through a small stream to Clear Lake. A steady, year round flow of 1 to 2 cfs occurs in this stream. A portion of the outflow from Collard Lake flows to Clear Lake through sand that forms their western boundaries. Clear Lake water flows out by a surface stream to Ackerly Lake and then to Munsel Lake and Munsel Creek or it seeps into the sand aquifer system directly from the lake. Bottom material in Clear Lake is mostly clean sand. Small deposits of clay and organic mud occur along the north shore, in coves along the east shore, and at the outlet. These small clay and mud deposits are also the spots where a few macrophytes grow: water lilies, water shield, and rushes.
The most obvious features of the surrounding landscape are the areas of bare, mobile sand which contrast strikingly with the general forest cover. On the west side of the lake is the exposed ridge of a large active sand dune that is moving slowly eastward, encroaching on the water. Sand is constantly deposited in the lake on this side so that the bottom slopes away gently from the shore. In contrast, there is a steep slope on the east side of the lake basin where it abuts the abrupt rise of the Coast Range. The original forest on the eastern side of the drainage basin has been mostly logged off and is now covered partly by a second growth conifer forest, mixed with deciduous species, and partly by brush such as salal, rhododendrons, and huckleberry. Most of the land on these forest and brush covered slopes is owned by private timber companies. Development around Clear Lake is minimal. There is one house with a boathouse on the lake shore and, in the past, a sawmill was located at the north end near the inlet. The lake is reported to contain cutthroat trout and largemouth bass, but is certainly not fished heavily, nor used for any other recreational purposes.
Most coastal lakes in Oregon are either mesotrophic or eutrophic, due to a combination of heavy use, shallow depth, and rapid infilling of sediment. Clear Lake, however, is quite deep and is one of the few oligotrophic lakes on the coast. Woahink Lake and the Clear Lake south of Reedsport are two other examples of deep, oligotrophic coastal lakes. The water quality in Clear Lake is generally excellent. Chemical constituents exist in low concentrations due to the relatively inertquality of fresh sands and the high flushing rate from heavy rainfall and rapid groundwater movement. There is only slight enrichment of sodium and calcium and the alkalinity is very low. The concentrations of phosphorus and chlorophyl and the transparency indicate a lower trophic state than in Collard Lake which discharges into Clear Lake from the north. All indications show that Clear Lake is relatively unproductive. Phytoplankton densities are low and only about 10 percent of the lake is shallow enough to permit the growth of macrophytes; they are not a problem as in so many of the coastal lakes. The phytoplankton densities and species reflect oligotrophic conditions. Cyclotella stelligera, which was dominant in May 1982, is also found in other oligotrophic lakes such as Woahink Lake, Clear Lake south of Reedsport, and Bull Run Lake on Mt. Hood. In November 1982 the phytoplankton was dominated by Rhodomonas minuta, which occurs in all types of lakes and is unreliable as an indicator species. Other algae found in November are Dinobryon bavaricum, often associated with waters having low phosphorus concentrations, and Rhizosolenia eriensis, which is also found in oligotrophic Bull Run Lake.
The use of Clear Lake as a domestic water supply is certainly appropriate, but its continued use as an unfiltered source will require special protection from potential increases in nutrients. The potential for future degradation of this supply is very real. The Lane Council of Governments (L-COG) recently completed an extensive study of the North Florence Dunal Aquifer and the surface water of lakes and streams on the dune sheet (Christensen and Rosenthal 1982). The purpose of this study was to identify the existing and potential effects of development, especially on-site sewage disposal methods, on the quality of the water. The primary concern is that present and future development within the Clear Lake drainage basin will increase nitrate-nitrogen (NO3-N) levels in the lake water which would likely result in higher densities of phytoplankton. Lake data collected and analyzed during the L-COG study indicated that the phytoplankton are nitrate limited. The data show that the lake has an average NO3-N concentration of 0.05 mg/L. In order to protect the lake from adverse algal growth and quality degradation, the study determined that this average NO N concentration must not increase. The Clear Lake Aquifer drainage basin presently receives a loading of approximately 600-700 pounds NO3-N/year. Calculations indicate that with the volume of water discharged from the aquifer to Clear Lake, the NO3-N loading will have to be 170 pounds per year to meet the target level of 0.05 mg/L. The difference between the present 600-700 pounds loading and the projected 170 pounds loading and the impact on the lake is attributed to the inherent delay in the movement of the present loading through the aquifer to the lake. In other words, the aquifer is presently receiving a NO3-N loading which might be sufficient to have an impact on the lake but an impact is not being observed because of the time required for the nitrate to move through the groundwater to the lake.
The list of plants below includes results of aquatic plant surveys conducted by the Center for Lakes and Reservoirs as well as aquatic invasive plant species detections that have been reported to iMap Invasives: an online, GIS-based invasive species reporting and querying tool.
Plants listed in the table below are categorized as native to Oregon, on the Oregon Department of Agriculture’s (ODA’s) Noxious Weed List, on the Federal Noxious Weed List, or non-native but not listed as noxious. Federal Noxious Weed List plants are plants determined by USDA to be serious threats to U.S. agriculture, irrigation, navigation, public health or the environment (7 C.F.R. 360.200). The ODA Noxious Weed categories are:
ODA Class A - weeds either unknown or with small enough infestations to make eradication or containment possible; targeted for eradication or intensive control.
ODA Class B - regionally abundant weeds (may have limited distribution in some counties); targeted for local/regional control on case-by-case basis.
|-||Utricularia vulgaris (common bladderwort)||Native||CLR|
|-||Typha latifolia (common cat-tail)||Native||CLR|
|-||Elodea canadensis (common elodea, Canadian waterweed)||Native||CLR|
|-||Najas flexilis (common naiad)||Native||CLR|
|-||Nymphaea odorata (fragrant waterlily)||Non-native||CLR|
|-||Potamogeton gramineus (grass-leaved pondweed)||Native||CLR|
|-||Equisetum sp. (horse tail)||Native||CLR|
|-||Potamogeton amplifolius (large-leaf pondweed)||Native||CLR|
|-||Chara sp. (muskwort)||Native||CLR|
|-||Eleocharis acicularis (needle spikerush)||Native||CLR|
|-||Potamogeton epihydrus (ribbonleaf pondweed)||Native||CLR|
|-||Juncus sp. (rush)||Native||CLR|
|-||Juncus supiniformis (spreading rush)||Native||CLR|
|-||Schoenoplectus subterminalis (water clubrush)||Native||CLR|
|-||Brasenia schreberi (watershield)||Native||CLR|
|-||Isoetes occidentalis (western quillwort)||Native||CLR|
|-||Nuphar polysepala (yellow water-lily)||Native||CLR|
|Aug. 15, 2003||Nymphaea odorata (fragrant waterlily)||Non-native||IMAP|