Ecoregions | East Cascades

Boundaries & Crossings:

East Cascades ecoregion makes up about 10% of all land in Washington state, beginning with the mountains east of the Cascade crest to the foothills that eventually flatten out to become the Columbia Plateau. Lake Chelan is its beginning in the north while the Columbia River Gorge marks its southern edge. Vehicular travel through this mountainous ecoregion at 5 primarypoints.Highway2allowspassagefrom the Puget Trough to cities such as Leavenworth and Wenatchee. In its southern end, I-90 slips through the Cascades passing near Cle Elum. Highway 2 and I-90 both connect to Route 97 and Alt Route 97, which is the most direct path to reaching Lake Chelan. Highway 410 and Highway 12 provide scenic routes through Mt Rainier National Park, with Highway 12 being the southernmost path to cross the ecoregion.

Landforms:

The Columbia River delineates the northeaster edge of the ecoregion before turning east into the Columbia Plateau. The river winds through the state and returns to the southernmost edge of the ecoregion at the bottom of the state.

Climate:

The climate dramatically drys out eastward of the Cascade crest. The crest acts as the beginning of the climatic gradient, with the ridge line receiving over 120 inches of annual precipitation (mostly snow) and lower elevations fall within the rain shadow over the foothills with a milder 20 inches of annual precipitation. Frigid mountain temperatures also gradiate as the elevations decrease giving the ecoregion a wild range in its growing season. East Cascades ecoregion’s growing season can vary from a high of 220 days to as little as 30 days depending on the elevation.

Ecoregions | Okanogan

Boundaries & Crossings

The Cascades, the Rockies, and the Columbia Plateau in north-central Washington converge to form what is known as the Okanogan ecoregion. The vast (14% of all land in WA) and rugged area can be defined as the mountains between mountains, known for its scenic highland views existing between the North CascadesandtheNorthernRockies.Theregion abuttingtheEastCascadeecoregionandLake Chelan is known for its pleasant north-south running river valleys such as the Methow and the Okanogan. After passing through the East Cascades, Highway 97 provides connection through Okanogan Valley. State Route 20 is seasonally open, connecting the Puget Trough and northern Cascades with Methow Valley and small tourism towns such as Winthrop and Twisp.

Landforms

Geologically speaking, the origin story of this ecoregion is complex and long involving volcanoes, plate tectonics, and glacial sculpting from the ice age. Its worth noting that much of the energetic glacial activities are also responsible for form Lake Chelan, regardless of it technically lying outside the Okanogan ecoregion. Over 11,000 years ago during the Pleistocene era, much of the Okanogan was coveredinglaciers.Foreonstheice,formedand retreated, grinding away at the land beneath, picking up and moving rocks, minerals, and soil as it did. The final retreat of these glaciers was the end of the ice age and left behind what is now the physical form and face of this ecoregion. The Columbia River forms the Okanogan ecoregions most southern edge.

Climate

Extremes of both hot and cold can be expected in the Okanogan ecoregion. It’s known for hot, dry summers and brutally cold snowy winters. The western edge of the region settles under the rain shadow of the Cascades, receiving 12 inches of precipitation annually. In contrast, the eastern boundary of theregiontheamountofprecipitationdoubles due to the storm fronts occurring against the rising Canadian Rockies.

Summer months bring hot air flowing up from the Columbia Plateau, causing sweltering temperatures in the high 90s and regularly breaking into the triple digits. The winter months bring choking arctic air streams from Canada, responsible for the states coldest temperature ever recorded, a deathly -48º F in Winthrop, only an hours drive from Lake Chelan.

Ecoregions | Columbia Plateau

Boundaries & Crossings:

Occupying nearly 1/3 of Washington State’s land mass, the Columbia Plateau is a vast semi-arid landscape stretching between the Cascades and the Rockies, trenched with the flows of both the Columbia and Snake Rivers. The northernmost boundary abuts the Okanogan highlands; its entire western edge kisses the East Cascades and is bordered by theRockiesandtheBlueMountainstoitssouth and southeast, respectively. Running eastwest, I-90 connects many of the cities within this region, such as Ellensburg, and Moses Lake, to Spokane on the eastern edge of the state.Highway2isanotherprimaryconnector, springing from route 97 near Wenatchee in the East Cascade ecoregion, eventually passing through Coulee City and eventually rolling its way to Spokane. The famed agricultural heartland of Washington is also within the Columbia Plateau ecoregion, with the rolling hills of the Palouse making up its southeastern edge.

Landforms:

Jumping in the way-back context machine, nearly 17 million years ago, a wild flood of lava flowed over this area for approximately 10 million years. As a result, this ecoregion was covered in basalt rock (cooled and hardened lava), in some areas a little over a mile thick. Atopthisbedrockisalayerofsiltsandvolcanic ash blown in from the Cascades, which resulted in the rich and fertile loess soils and agricultural lands which stretch to the Palouse region of the Columbia Plateau.

More recently, and closer to the region border shared near Lake Chelan, massive flooding associated with the Glacial Lake Missoula sculpted what is now known as the Channeled Scablands of eastern Washington, leaving behind its famed coulee landscape.

Climate:

TheColumbiaPlateauishighlyaffectedbythe Cascade’s long and enduring rain shadow. Summers in this region are known to be hot and dry, with cold gray winters. Late fall and early spring provide most of the region’s precipitation. In correlation with the given elevation, annual precipitation averages range from 6 to 25 inches. Snow falls within the region; however, it is mostly wet and quick to melt. The maritime effect moderates lower elevations from across the state, and the annual average temperature mildly rests between 40 to 57 degrees. Still, extremes of triple digits and subzero are not uncommon, along with occasional drought or forest fires.