Bonaparte Lake is a large freshwater lake in the northwestern Okanogan Highlands of Washington, United States. It is the largest lake in the Bonaparte Creek watershed and is both fed and drained by said creek. The lake is at the eastern foot of Mount Bonaparte and abuts the Bonaparte Meadows calcareous fen. The lake was formed by a partial blockage of the valley mouth by glacial debris at the end of the Fraser Glaciation and the deep peat deposits of the Bonaparte Meadows preserve ash falls from Mount Mazama and Mount St Helens. The is about long with a north–south directionality while a land neck separates the southern 1/3 into a smaller basin from the remaining 2/3 in the northern area. A maximum depth for the lake is while the area is .
The lake provides boating and sport fishing opportunities facilitated by the national forest campground on the southern shore, the public resort on the eastern shore, and the Scouting America camp on the northern shore. Cold winter temperatures allow for deep lake ice formation and ice fishing in the central winter months.
The flora of the lake and meadows is diverse with nonvascular plants like mosses, liverworts, and lichens. Aquatic plants include several pond weeds, possibly two water-lillies, and a scattering of others single species taxa. Diverse grasses, sedges, and rushes are found across the marsh and around the lake. Aspens, birch, maple, pine and spruce grow as scattered individual trees, small groves, and comprise the surrounding forest.
The fauna known from the lake area is sparsely documented, with scattered reports for snails, spiders, insects, birds, and amphibians. The most documented are the mammals and the fish. Of the invertebrates, a single snail and a few scattered insects are known, while a restricted but diverse spider fauna including trap-door spiders are present. Fish species found in its waters include trout, salmon, and freshwater bass. The tributaries of the lake are considered likely habitats for native kokanee, while non-native trout have been planted since at least the 1930s. Due to the history of stocking, the true genetic origins of upper Bonaparte watershed salmonids is considered clouded. The lake is one of several in the state where nesting Common loons and black terns are present in the summer while reports of both sea ducks and Phalarope have been made. The meadows are a known habitat for the Washington species of concern Columbia spotted frog. Mammals using the area include herbivores like moose and deer, three felines, two canines, a mustelid and a bear.
The area has a known history of wildfires, with large blazes in 1977 and 2021. Despite the threat of fires yearly, the larger area is not part of any Okanogan county fire district, and is instead overseen by the Washington State Department of Natural Resources which maintains mutual aid agreements with multiple other organizations.
Human use of the area has been varied in nature, originally being part of the ancestral lands used by the Syilx peoples prior to the creation of the Colville Indian Reservation. A low agricultural and residential use dam was built on the south end of the lake for water diversion in the early 1900s. The region was included in a state game reserve for nearly ten years before the reserve was decommissioned in favor of hunting use. Two campground areas, a national forest camp and a scout camp, plus an public resort are on the shores. Annual trout stocking has occurred since at least the 1930s for fishing, with ice fishing becoming popular in the late 2000s.
Location and access Bonaparte Lake is in the upper reaches of the Bonaparte Creek drainage basin, a subbasin of the Okanogan River, itself part of the greater Columbia River drainage. The lake is at the southeastern foot of the Mount Bonaparte, the highest mountain in the Washington section of the Okanagan Highlands and one of the highest peaks in the greater Okanagan Highlands. The mountain rises between the unincorporated communities of Havillah and Wauconda, while the closest cities are Tonasket to the southwest and Republic to the southeast.
The southern end of Lake Bonaparte is north of SR 20 on County Road #4953 which then transitions to Forest service road 32. The road runs along the eastern shore of the lake and provides access to private residences and the lakes area north of Bonaparte. The area surrounding the lake is 95% National forest managed, and 5% Department of natural resources. Two motorized boat launches service the lake, both at the southern end, on the south and the southeastern shores. The shores are host to aquatic plant growth and easy water access is limited to the national forest campground and the private resort.
The lake was accessible by automobiles on roads passing though Molson or Republic as early as 1920. The lake was already regionally noted in 1920 for the fishing opportunities and for camping.
Dimensions and depth The lake is approximately long and trends generally south to north, with the northern area of the lake transitioning into emergent wetlands complexes, providing connectivity to a series of small lakes north of Bonaparte. In 2007 the lake acreage was given as and a water line elevation of . The water is clear and the lake bottom is a gravel and silt mix. A majority of the lake as a whole is deep, having shallows only near the central necks and Bonaparte Creeks outflow in the south, while in the north there is a central marked shallow and shallows associated with a bay in the northeast corner. The average depth of the south half is with a maximum of . In the northern half the deepest sections of the lake bottom out at . Near the center of the lake a neck of land extends from both shores, with the northern section larger than the southern section, with two-thirds in the north half and one third in the south.
Geology Bonaparte Lake was formed at the end of the most recent ice-age. The valley opening was damned by glacial moraine deposits dropped from the melting Okanagan ice lobe. Subsequent to the valley infilling with lake waters areas at both the northern inflow and southern outflow experienced peat moss growth with gradual transition to peat fen. The southern section of what formerly was lake has fully transitioned into the Bonaparte meadows fen, through which Bonaparte Creek drains before leaving the valley fully. The peat deposits have been subjected to small scale mining for local sale since the 1950s. A section on the northern end of the lake has shifted to a swamp biome which overlies peat deposits. The surface area has a water layer with a growth of aquatic vegetation, while the underlaying peats area between deep.
Examination of the peat areas of Washington by George Rigg, an expert in bogs and wetland ecology indicated the Okanogan Highlands, defined as from the eastern border of the Cascades to the Washington-Idaho border, had the second most extensive peat deposits of the state after the Puget Sound area. The expanded highlands hosts about 14% of Washingtons peatlands in 44 distinct sites. Rigg noted the distribution of pumicite in the bog suggested that the thick layering near the bog edges was due to sedimentation from surrounding the bog after the pumicite fall initially happened, with the center area of the bog showing a thinner total deposition layer. Bore-holes made by Rigg indicated total peat depths ranging between in the deepest parts of the meadows, with a sedimentary peat layer up to thick and some pumicite layers up to thick. Rigg attributed all the pumicite deposits as most likely from the 6,000 year Glacier Peak eruption. The basement layers of the bog are underlaid by gravels, clays and course sands.
Investigation of the Bonaparte Meadows floral history in 1979 by Mack, Rutter, and Valastro reidentified the pumicite deposits in the meadow area as three distinct falls from two separate volcanic events, neither of which was the Glacier Peak eruptions. The older two falls are both from the 6,800 ybp catastrophic Mount Mazama eruption which started the formation of Crater Lake. The older fall is comprised of fine silt sized particles, while the younger fall is larger sand size particles with a measurable amount of phenocrysts. A third anf fainter deposit was found in the uppermost zone of the fen, and
Climate
Within the Köppen climate classification the area of northeastern Okanogan County has a humid continental climate (Dfb). The 30-year average temperature is , with an average yearly high of in August, and an average low of in December. The average rainfall is per year. The wettest month is June, with of precipitation, while the driest is August, with .
The lake freezes over during the winter, with thick enough ice layer developing by January to support ice fishing. On average the ice cover starts to melt off during April though the timing is variable, and is typically fully gone by May. Historic reporting from 1917 documented Bonaparte Lake and other lakes in the area were still covered in ice as of reporting on May 11, while rivers and creeks surrounding were running high.
Ecology
Located in the transition zone from lowland Okanogan basin Ponderosa pine forest and mid elevation mixed conifer forest. The ponderosa pine zone is found between in elevation, though the higher elevation areas are often restricted to south facing slopes or ridge lines. The general appearance is open and park-like with widely scattered old growth trees. Frequent ground fires maintain the open park nature, with isolated groves of young ponderosa or Douglas fir acting as nexus points of tree regeneration. The mid elevation mixed conifer forests are typically found between and cover most slopes and aspects of the terrane. In these Douglas fir dominated forests the structure ranges between open and park-like though dense stands with multistory canopies. When understory tress are present in the forests, they are dominated by shade tolerant species such as grand fir or young Douglas fir. When the forest is of mixed density to open, additional tree diversity is found with lodgepole pine, western white pine, and western larch.
Bonaparte Lake was evaluated in accordance with the Washington State Department of Natural Resources Aquatic Reserve program expansion survey, and detailed in the 2017 initial survey report. major criteria included species concentration, rarity, and diversity of species, also importance to Washington bird species. Plants were looked at in terms of community diversity and species rarity. In addition to species parameters the overall body of water was assessed based on connection to other protected areas, such as wetlands, terrestrial, or fluvial environments. A group of only ten lakes were singled out as potential aquatic reserve bodies, with Bonaparte Lake the only lake in the Okanogan Highlands, and one of four lakes in northeastern Washington. The primary criterion for inclusion was it being an annual nesting site for Common loons and one of only two nesting areas that are fully on state owned aquatic land. Two other species of interest were called out as focus species. The lake is also a nesting site for black terns, and is a native waterbody for Kokanee trout which spawn in the lake tributaries.
Historic floral succession