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Nez Perce County Comprehensive Plan


Natural Resources


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Numerous natural resources and natural hazards present both opportunities and limitations for future development in Nez Perce County. The purpose of this element of the comprehensive plan is to define the various natural resources in the planning area and to identify the limitations and opportunities inherent in Nez Perce County's environment.



Nez Perce County has much variation in climate because of differences in elevation. Winters are mild with very little snow cover and summers are dry and hot. The climate in the valleys is relatively warm, with January being the only month in which the mean temperature is below 32 degrees Fahrenheit. The climate at higher elevations (e.g., the plateau and mountain areas) is cooler and receives considerable snowfall in the winter months.

Some areas, notably the Lewis-Clark Valley, are subject to periodic temperature inversions that result in air stagnation and a buildup of air pollution consisting of industrial emissions, motor vehicle emissions and dust from roads, streets and agricultural operations.


Nez Perce County topography varies widely, from flat river valleys and gentle plateau lands to steep canyon walls and the slopes of the Waha escarpment and Craig Mountain. Elevations range from 720 to 5,395 feet.

Distinguishing features of the county are several important river basins: the Potlatch, the Clearwater, the Salmon, and the Snake. The Snake river forms the western boundary of the county, as well as the Idaho-Washington and Idaho-Oregon state boundaries. The lower reaches of the Salmon River to its confluence with the Snake River are the southeastern boundary of Nez Perce County. The Salmon River runs east generally to west, in a deep walled canyon. The Clearwater River runs east to west from the northern part of the county to a confluence with the Snake River at Lewiston. The Clearwater has a narrow river valley with canyon breaks that are not as steep as those of the Snake and Salmon Rivers. The Potlatch River, smallest of the four rivers, forms a portion of the northern boundary of the county. It enters from the north and flows southerly in a fairly deep canyon to a confluence with the Clearwater about 10 miles east of Lewiston.

The high land north of the Snake and Salmon River breaks is known as Craig Mountain. The highest elevation is 5,395 feet. From these heights, the plateau breaks off sharply to the west, forming the east wall of the Snake River canyon, and more gently to the east and north toward the Clearwater River, except where broken by the steep Waha escarpment.

Northwest of the Clearwater River is a portion of the Palouse plateau. In the northeastern part of the county there is a small isolated plateau lying between the Potlatch River and the Clearwater River known as Potlatch Ridge. In addition to the valleys and canyons of the major river system, lesser streams have formed valleys that were historically areas of settlement. Lapwai Creek has a wide valley floor that was occupied by generations of the native Nez Perce Indians, and later became a focal point for some of the earliest settlement by white men. Other such valleys are the Cottonwood Creek and Mission Creek Valleys, and the valley and canyon of Big Canyon Creek, which form part of the northeastern boundary of the county.


Nez Perce County is on the eastern margin of the Columbia River Plateau, a large area that was covered by lava (basalt) flows in Miocene times. The terrain covered by the flows was very irregular; therefore, the depth of the lava varies widely from place to place. Elevated portions of the old pre-lava surfaces are exposed in places, like islands surrounded by basalt.

There were several flows laid down over an epoch of thousands of years. Between some of the lava flows there were long periods of inactivity in which weathered surfaces developed. Sediment washed from the weathered surfaces and was deposited in lakes, streambeds, or depressions along the eastern margins of the basaltic plain. Later, lava flows covered these weathered slopes and deposits of sediment, forming a layer of sand, gravel, silt, and volcanic ash known as the "Latah beds", but they are exposed on canyon walls below the elevation of the present plateaus. Deposits of sand, gravel, and clay, of economic value, are found in some of these Latah beds.

Along the Snake and Salmon Rivers on the southwestern border of Nez Perce County erosion has uncovered metamorphosed rhyolite and pyroclastics related to the Seven Devils volcano. The color of these rocks is predominately green and they are commonly designated greenstone.

Recent stream action has produced sand and gravel bars along the present course of the rivers. Deposits of sand, gravel, silt, and boulders in former stream channels are found in the Lewiston area. These deposits are worked to some extent for the sand and gravel. Other deposits are on the floor of the Lapwai Valley and in the Cow Creek area south of Genesee.

Soil Resource:

Soil should be considered Nez Perce County's most important natural resource, because soils provide the basis for forestry and agriculture--the foundations of the area's economy. All soils within the county have been classified by the Natural Resources Conservation Service (formerly the Soil Conservation Service) based on their potential uses and limitations.

The Natural Resources Conservation Service has established eight soil capability classes based on potential productivity and management practices required. Following are the general descriptions of these classes.

Class I - Soils are productive and adapted to a wide range of crops. Soils do not require special conservation or management practices. In Nez Perce County these are limited to a few small areas, mainly in valley bottoms.

Class II - Soils have moderate limitations that reduce the choice of plants or require moderate conservation practices. In Nez Perce County these are found mainly in the flatter areas south of Tammany Creek.

Class III - Soils have severe limitations that reduce the choice of plants and/or require special limitations that reduce the choice of plants and/or require very careful management.

Class IV - Soils have very severe limitations that reduce the choice of plants and/or require special limitations that reduce the choice of plants and/or require very careful management.

Class V - Soils have severe limitations that make them better suited for pasture, woodland or wildlife than for cultivation.

Class VI - Soils have very severe limitations that make them generally unsuited to cultivation and limit their use largely to pasture, woodland or wildlife.

Class VII - Soils have very severe limitations that make them unsuited to cultivation and restrict their use largely to pasture, woodland or wildlife.

Class VIII - Soils are not capable of any beneficial production.

Nez Perce County soils are mainly classified from Class II through Class VII. Class I soil areas are limited because nearly all the soils in the county have specific limitations requiring some conservation practices.

Land Ownership Patterns:

Land ownership is not in itself a natural resource. However, it is important to indicate land availability as well as its capability.

A sizable portion of Nez Perce County lies within the Nez Perce Indian Reservation. The Bureau of Land Management administers federally owned lands. State-owned lands are under the jurisdiction of various state agencies.

Private lands include all land classified as deeded lands. City and County-owned lands are classified as private lands under public ownership.

The vast majority of agriculturally productive lands are privately owned, with scattered holdings under tribal ownership. Current tribal policy favoring future acquisitions and consolidations of land could provide the tribe with a stronger agricultural base.

Water Resources:

Despite the generally moderate precipitation and dry nature of most of the farmland, water resources are generally quite abundant in Nez Perce County. In addition to the several rivers, there are a large number of creeks and small streams, many of which flow the year around. The waters of nearly all of these flow into the Clearwater-Snake River system, which ultimately flows into Lower Granite Reservoir. Cow Creek in the extreme northwest corner of the county is the only stream that does not drain to the Clearwater-Snake system, but flows to the Palouse River instead. The total annual flow into Lower Granite Reservoir averages just over 35 million acre-feet. Groundwater is also abundant.

The uses of these water supplies are varied. A slack water navigation system exists to Lewiston, making it Idaho's only seaport. Water-based recreation is a significant economic resource in addition to its value as a source of relaxation and entertainment. Several industries in the county require water in their processing and these uses are expected to expand.

Nez Perce County also contains a large portion of the Lewiston Basin Aquifer. This natural underground water supply was designated a sole source aquifer by the U.S. Environmental Protection Agency October 3, 1988. The Lewiston Basin Aquifer covers approximately 400 square miles of Western North-Central Idaho and Southeastern Washington. In order to receive this designation an underground water supply (aquifer) or aquifer system must supply 50 percent or greater of an area's drinking water. Groundwater supplies approximately 68 percent of the drinking water for population within the Lewiston Basin.

The Lewiston Basin aquifer is principally replenished (recharged) by stream flow infiltration from portions of the Clearwater River, Lapwai Creek, Snake River, and Asotin Creek. It is for this reason that surface water quality must be protected to maintain the Lewiston Basin's drinking water quality. The importance of high quality sources of drinking water is obvious. Given the general abundance of water, the county's continued concern will be with the quality of its waters.

Pollution prevention must be the first step in improvement of the quality of Nez Perce County's surface and ground waters. Performance standards, applicable to all types of development that could have a deleterious effect on the water, should be established to reduce or prevent further pollution.

Mineral Resources:

Nez Perce County contains various mineral resources such as gold, silver, copper, limestone, clay and some gemstones. Nez Perce County is not currently a supplier of metallic minerals; however, some claims were recorded in the extreme southern portion of the county in the Salmon River breaks, and several claims in the Deer Creek area southeast of Waha. In the early days the Deer Creek mining area produced gold, silver, and copper. There was a gold stamp mill at nearby Za Za in the Craig Mountain area.

Forest Resources:

Of Nez Perce County's total area of more than 545,107 acres, about 129,153 acres (24 percent of the county) is classified as forestland. Not all of this is of a quantity or quality to make it suitable for commercial harvesting, but most of this area is capable of producing valuable timber resources.

Tree species are predominantly Ponderosa Pine, Douglas Fir, and true firs, with some spruce and other species. Significant amounts of timber are harvested in Nez Perce County.

A large part - perhaps a majority - of the timberlands are also suitable for grazing although the steeper canyon slopes (over 60 percent) are generally not grazed. Areas in which natural tree reproduction is desired also should not be grazed until young trees are well established.

Timber management and harvesting are regulated by the Idaho Forest Practices Act. The stated purpose of the act includes "to encourage forest practices on forest lands that maintain and enhance their benefits and resources." Notification to the state is required before any of the following forest practices are undertaken: harvesting, road construction or reconstruction associated with harvesting, reforestation, application of insecticides, herbicides, rodenticides or fertilizers, and disposal or management of slash.


Goal Statement:

To manage Nez Perce County's natural resources so as to provide for future as well as present needs.


  1. Nez Perce County should encourage the conservation of stock (non-renewable) resources through careful utilization, minimizing of waste and maximizing efficiency of use.
  2. Nez Perce County should encourage planning of resource consumption rates to emphasize future rather than present consumption.
  3. Nez Perce County should promote the utilization of renewable resources at rates not exceeding their renewal capacities and safeguard their quality for future generations.
  4. Nez Perce County should encourage water and soil conservation measures through cooperation with the Natural Resource Conservation Service, the Clearwater Resource Conservation and Development Area, the Nez Perce Tribe, the Lewiston Orchards Irrigation District, and similar entities.
  5. Nez Perce County should safeguard air and water quality through pollution control and performance standards in cooperation with other agencies for industrial and commercial development in sensitive areas.
  6. Nez Perce County should encourage the conservation of land most capable of crop and timber production.
  7. Nez Perce County should encourage owners of timberlands to take advantage of technical assistance, available through state foresters and the Natural Resource and Conservation Service.
  8. Nez Perce County should encourage the conservation of existing energy resources and develop new energy sources.
  9. Nez Perce County should encourage the development and utilization of renewable or alternative energy sources compatible with environmental and public safety.
  10. Nez Perce County should encourage the development and use of energy-saving measures, such as public transit, water transportation and energy-conserving construction and farming methods.

Natural Resources Strategy Chart


Planning & Building
Office Location
Brammer Building
1225 Idaho Street
Lewiston, ID 83501

Mailing Address
P.O. Box 896
Lewiston, ID 83501



Alison Tompkins

E-mail Alison

Building Official

Kile Allen

E-mail Kile

Senior Customer Service Specialist

Cody Lorentz

E-mail Cody

Planning & Zoning

Commission Chairman

Frank Dillon

Vice Chairman

Shawn Wentworth


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