Coffenbury Lake (Clatsop)

Reachcode: 17080006006562 | Area: 51.2 acres | Shoreline: 2.4 mi | View on Interactive Map

(From Atlas of Oregon Lakes, Johnson et al. 1985).  Coffenbury Lake is a long, narrow and shallow water body located in the northern Clatsop Plains about one-half mile from the Pacific Ocean. It is a typical coastal interdune lake situated between parallel relict dunes that trend north and south. There are no inflowing or outflowing streams, and the lake level fluctuates with seasonal changes in the water table, from about 16 feet above mean sea level in the fall to about 22 feet in the early spring. The surrounding area consists of well-drained, sandy soils which support a dense forest of spruce and fir and deciduous species such as willow, crabapple and alder.

Located in Fort Stevens State Park, Coffenbury Lake is very popular as a family recreation site for boating, swimming and fishing. Cutthroat and rainbow trout, yellow perch, and catfish are taken by anglers; nevertheless the lake does not have the reputation of being a particularly good producer. A boat launch is located at the north end of the lake and a 10 mph speed limit is in effect. Although there is no camping at the lake itself, a large state park campground nearby is one of the most heavily used in the state. Two bathhouses serve the needs of swimmers at beaches on the east and northwest shoreline.

Coffenbury Lake is exposed to the prevailing flow of marine air and does not stratify. Sodium and cloride concentrations and the conductivity are slightly above average for coastal lakes in Oregon, reflecting proximity to the ocean. The water is moderately stained with organic matter derived from swampy portions of the drainage basin. This moderate nutrient enrichment is also due to the presence of humic materials leached from the peaty material on part of the lake bottom.

Beds of water lilies and other macrophytes stand along the shoreline, but are less extensive than might be expected for such a shallow lake. Reduced water transparency (6.0 feet; 1.8 meters) is probably responsible for this fact. In contrast, Coffenbury Lake has shown a diversity of plankton along its length which is quite unusual for a lake this small. This diversity may be related to the type of bottom sediments. For example, it was observed in 1969 that Anabaena circinalis was the dominant form in the sandy north end, but was not observed in the muddy, peaty south end where Anacystis aerugmosa and Melosira granulata were co-dominant. The combination of these chemical and biological factors allows Coffenbury Lake to be classified as mesotrophic, although it is very close to eutrophic.

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No mussel data available.

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.

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Date Species Status Source
June 18, 2003 Veronica catenata (chain speedwell) Native CLR
June 18, 2003 Utricularia vulgaris (common bladderwort) Native CLR
June 18, 2003 Ceratophyllum demersum (Coontail; hornwort) Native CLR
June 18, 2003 Lemna minor (duckweed) Native CLR
June 18, 2003 Potamogeton zosteriformis (eel-grass pondweed) Native CLR
June 18, 2003 Potamogeton natans (floating leaf pondweed) Native CLR
June 18, 2003 Hydrocotyle ranunculoides (floating marshpennywort) Native CLR
June 18, 2003 Sparganium angustifolium (narrowleaf bur-reed) Native CLR
June 18, 2003 Eleocharis acicularis (needle spikerush) Native CLR
June 18, 2003 Callitriche hermaphroditica (northern water-starwort) Native CLR
June 18, 2003 Elodea nuttallii (Nuttall's waterweed, western waterweed) Native CLR
June 18, 2003 Crassula aquatica (pygmy-weed) Native CLR
June 18, 2003 Phalaris arundinacea (reed canarygrass) Non-native CLR
June 18, 2003 Juncus sp. (rush) Native CLR
June 18, 2003 Nitella sp. (stonewort) Native CLR
June 18, 2003 Potamogeton sp. (thin leaved) (thin leaved pondweed) Native CLR
June 18, 2003 Vallisneria americana (water celery) Non-native CLR
June 18, 2003 Oenanthe sarmentosa (water-parsley) Native CLR
June 18, 2003 Ludwigia palustris (water-purslane) Native CLR
June 18, 2003 Persicaria amphibia (water smartweed) Native CLR
June 18, 2003 Nuphar polysepala (yellow water-lily) Native CLR