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Soil Survey of Boundary County, Idaho


USDA – NRCS, Soil Survey Office
7830 Meadowlark Way, Suite C-1
Coeur d’Alene, ID 83814
208-762-4939 Ext. 110

State survey area: ID601
Soil survey area: 249,000 total acres (389 square miles)

Boundary County Soil Survey completed in 2003: mapping completed in 2000; database in progress

GENERAL: The survey area is located in the northernmost part of the Idaho panhandle bordering Canada. The survey area includes most of the private and state lands in the central and eastern parts of Boundary County but does not include the Kaniksu National Forest. The area consists of mountainous or hilly terrain; the broad Kootenai River valley; gently sloping benchlands; and other narrow valleys. Three mountain ranges occur within the survey area, including the Selkirk Mountains in the west, the Purcell Mountains in the northeast, and the Cabinet Mountains in the southeast. Besides the Kootenai River valley, other prominent valleys include Moyie River and Round Prairie valleys in the north and Deep Creek and Paradise valleys in the south.  Most of the survey area is woodland; however, a significant amount of acreage is used for hay and pasture and for crop production.

The lowest point, about 1,745-feet elevation, is along the Kootenai River near Porthill. Bonners Ferry, situated on a river terrace, is located at about 1,775-feet elevation. The highest elevations are in the southeast and southwest, where some mountain peaks are greater than 6,000-feet elevation. The total annual precipitation is about 23 inches, of which 35 percent falls in April through September. The average seasonal snowfall is about 67 inches. The average temperature in winter is 28 degrees F. In summer, the average temperature is 64 degrees.

SOILS: The soils in the Boundary County area formed from residual, glacial, lacustrine, alluvial and eolian parent material. The mountains are mainly residual material derived from Precambrian metasedimentary rocks and metamorphosed igneous rocks of the Kaniksu Batholith (Ross and Forrester, 1958). Most soils formed in residuum contain a high percentage of rock fragments and also have varying amounts of surficial loess and volcanic ash deposited during the late Pleistocene and Holocene Epochs (USDA, 1984). Many soils in the foothills and mountains formed in glacial till that consists of varying amounts of sand, silt, gravel, cobbles and stones and is covered by a surficial deposit of volcanic ash and loess. The volcanic ash is predominantly silt-sized material and originated from many active volcanoes in the Cascade Range, with the greatest contribution of ash coming from Mt. Mazama approximately 6,700 years ago. The high terrace or benches adjacent to the Kootenai River flood plain are primarily silty, glaciolacustrine deposits many hundreds of feet thick. Soils formed in sandy, dune areas are associated with large deposits of eolian sand. Soils in the Kootenai River flood plain formed mainly in relatively recent silty, calcareous, alluvial deposits.

Major soils of the survey area include the following:
LEVEL TO UNDULATING, POORLY DRAINED TO MODERATELY WELL DRAINED SOILS ON FLOOD PLAINS AND DRAINAGEWAYS

  1. SCHNOORSON-DEVOIGNES-FARNHAMTON: very deep, level to undulating, poorly drained to moderately well drained soils on flood plains

  2. SEELOVERS-TYPIC FLUVAQUENTS-AQUIC UDIFLUVENTS: very deep, level to undulating, poorly drained and somewhat poorly drained soils on flood plains and drainageways

NEARLY LEVEL TO HILLY, WELL DRAINED, MODERATELY WELL DRAINED, AND EXCESSIVELY DRAINED SOILS ON OLD GLACIAL LAKE LAID OR GLACIAL OUTWASH TERRACES OR BENCHES

  1. RUBSON-PORTHILL-FRYCANYON: very deep, nearly level to rolling, well drained and moderately well drained soils on old glacial lake laid terraces or benches
  2. SELLE-ELMIRA: very deep, nearly level to hilly, well drained and excessively drained soils on terraces and dunes
  3. STIEN-PEND OREILLE: very deep, nearly level to rolling, well drained soils on glacial outwash terraces or benches

STEEP AND VERY STEEP, WELL DRAINED SOILS ON TERRACE ESCARPMENTS AND CAYONSIDES

  1. WISHBONE-CABOOSE-CRASH: very deep, steep and very steep soils on terrace escarpments and canyonsides

STRONGLY SLOPING TO VERY STEEP, WELL DRAINED SOILS ON FOOTHILLS AND MOUNTAINS

  1. PEND OREILLE-IDAMONT-TREBLE: very deep, strongly sloping to very steep soils on foothills and mountains
  2. ROCK OUTCROP-MCARTHUR-JAYPEAK: very deep, steep to extremely steep soils and rock outcrop on mountains and breaklands
  3. RUBCREEK-REDRAVEN-BALDEAGLE: very deep, moderately steep to very steep, cold soils on mountains and ridgetops high elevations

 

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