Fourmile Lake (Klamath)

Reachcode: 18010203000427 | Area: 626.0 acres | Shoreline: 6.5 mi | View on Interactive Map


(From Atlas of Oregon Lakes, Johnson et al. 1985)  Fourmile Lake, so named because it was erroneously assumed to be four miles long, is a large natural lake scenically located at the foot of Mt. McLoughlin near the divide between the Klamath River and Rogue River Basins. At 5744 feet above sealevel it is one of the highest lakes in Oregon. The lake was enlarged artificially by the construction of a rock-faced, earthfill dam completed in 1922. Natural outflow is into Fourmile Creek, but a considerable portion of the water is diverted into the Cascade Canal and transported to the Rogue River Basin where it discharges into a lava bed one and one-half miles above Fish Lake. Here the flow sinks into the lava and reappears as springs at the head of Fish Lake. This diversion project is a component of the Medford Irrigation District which supplies irrigation water to the Ashland-Medford area.

Due to a naturally low level of biological production in the lake, it is stocked regularly by the Oregon Department of Fish and Wildlife and thus has a variety of fish species. Kokanee are probably the most numerous; eastern brook and rainbow trout are also in good supply. Because of its natural beauty Fourmile Lake is a favorite with many fishermen and other outdoor enthusiasts. A good Forest Service campground is located at the south end of the lake.

Fourmile Lake is surrounded by steep, forested slopes and the lake itself is very deep (maximum 175 feet) with relatively little shallow water. Because of the high elevation, water temperatures remain cool throughout the summer. The water in the lake has very low concentrations of ions, and low alkalinity and low conductivity. Phosphorus and chlorophyl concentrations are also low, and the water is very transparent. By all measures this lake is oligotrophic. Biological productivity as noted is accordingly low and limits natural fish production. A plankton tow taken on 7/15/82 yielded little more than a few copepods. Dinobryon bavaricum and Tabellaria fenestrata have been observed in previous samples. The only apparent macrophyte was Subularia aquatica, a small submergent plant commonly found in mountain lakes.


Printable Lake Map
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.

Download the complete dataset as a CSV

Date Species Status Source
Aug. 14, 2012 Sagittaria sp. (arrowhead) Native CLR
Aug. 14, 2012 Utricularia vulgaris (common bladderwort) Native CLR
Aug. 14, 2012 Callitriche heterophylla (different-leaved water-starwort) Native CLR
Aug. 14, 2012 Potamogeton natans (floating leaf pondweed) Native CLR
Aug. 14, 2012 Poaceae (grasses) Non-native CLR
Aug. 14, 2012 Ranunculus flammula L. var. reptans (greater creeping spearwort) Native CLR
Aug. 14, 2012 Eleocharis acicularis (needle spikerush) Native CLR
Aug. 14, 2012 Isoetes sp. (quillwort) Native CLR
Aug. 14, 2012 Carex sp. (sedge) Native CLR
Aug. 14, 2012 Potamogeton pusillus (slender pondweed) Native CLR
Aug. 14, 2012 Nitella sp. (stonewort) Native CLR