in
Prairie Grove The county is located in the
Ozark Mountains, a small mountain region between the
Appalachians and the
Rocky Mountains with distinct settlement patterns, history, and culture from surrounding agrarian regions (the
Interior Plains of the
Midwest United States and
Mississippi Delta to the southeast), and the flat ranchlands of the
Great Plains to the west. In the Ozarks, population density is low; recreation, logging, and poultry and livestock farming are the primary land uses. Pastureland or hayland occur on nearly level ridgetops, benches, and valley floors. Water quality in streams is generally exceptional. Most of the county is within the mountainous, forested
Boston Mountains, with the north and west portions made up of the nearly level to rolling
Springfield Plateau.
Karst features such as
springs,
losing streams,
sinkholes and
caves are common. Washington County has a total area of , of which is land and (0.6%) is water. It is the fourth-largest county by area in Arkansas.
Geology Washington County sits on a
basement of
Precambrian granite and
rhyolite, as most of the continental interior of the
United States does. Much of the county's geologic history must be inferred from nearby
Oklahoma and
Missouri research, due to the steepness of the more recently formed mountains that did not form in the neighboring states. This
igneous material was eroded until the
Paleozoic, when oceans covered the now-low-lying area. These oceans came and retreated for 300 million years, depositing various different sediments during that time. This created
fossiliferous limestone and
ripple marked-
sandstone, both present throughout the north part of the county as evidence of ancient oceans. The Devonian brought mostly
shales, the Mississippian brought the
limestones and
chert visible in the bluffs. This chert is present throughout most of the county. The county is also home to the Boone Formation (red soils), white limestones, the
Wedington Sandstone, the
Bastesville Sandstone, the
Pitkin formation (ocean-fossil limestone), and the
Fayetteville Shale. Settlers were attracted to the area by its numerous streams, used to power
gristmills,
sandstones and
clays for use in construction,
lime-sweetened soil, and chert for road construction. Today, Washington County consists of two main formations, the
Boston Mountains and the Springfield Plateau. During the late
Pennsylvanian,
sediments were deposited on top of the Springfield Plateau. The area was uplifted during the
Ouachita orogeny and subsequent erosion formed the rugged Boston Mountains. Erosion of these sediments causes the Boston Mountains to be carved steeply in the south, while in the north of the county, the Boston Mountain sediments are almost entirely eroded, exposing the older rocks of the Springfield Plateau.
Hydrology Washington County fits within three regional watersheds: the eastern half drains to the
White River (or Beaver Lake) and the west drains to the
Illinois River, with a small segment in the south draining to the
Arkansas River via the
Lee Creek watershed. Within the county, Clear Creek, Moore's Creek, Richland Creek, and Spring Creek are important watercourses. The county also contains eleven natural springs listed by the
United States Geological Survey Board on Geographic Names, including Elkhorn Springs, Elm Springs, and Greathouse Spring in
Johnson. As a mountainous county, it contains only one natural lake and several
reservoirs. Most of these reservoirs, such as Lake Prairie Grove and Lincoln Lake were created for flood control or water supplies in the 20th century.
Beaver Lake, located mostly in Benton County with reaches extending into Washington and Madison counties, is the sixth-largest lake in Arkansas, and a source of recreation, tourism, and drinking water for the Northwest Arkansas region. Washington County also contains
Lake Wedington, located in the Ozark National Forest west of
Fayetteville on
Highway 16.
Protected areas Washington County contains three discontinuous segments of the
Ozark National Forest, two state parks, two
Wildlife Management Areas (WMAs) under
Arkansas Game and Fish Commission jurisdiction, the Garrett Hollow Natural Area, and dozens of city parks. The
Wedington WMA is a
hardwood forest owned by the
United States Forest Service known for
archery, deer hunting, fishing, and boating on Lake Wedington. The southeast corner of Washington County contains part of the
White Rock WMA, an expansive section of the Ozark National Forest containing some of the steepest segments of the Boston Mountains covered in a mix of shortleaf pine and hardwood forest. White Rock WMA has six camping areas, four lakes, and numerous trails. Public hunting for squirrels, deer, wild turkeys, and black bear is available during certain seasons
Devil's Den State Park in southern Washington County is known for its picturesque views and mountain vistas.
Prairie Grove Battlefield State Park was the site of the
Battle of Prairie Grove, fought December 7, 1862, in the
American Civil War. The park offers tours of the battlefield and period structures and contains the Hindman Museum, which preserves artifacts and interprets the history of the battle. Arkansas's largest Civil War battle reenactment takes place on t he battlefield in December of even numbered years. ==Demographics==