CRATERS of the MOON General Management Plan

APPENDIX B:

CLIMATE

Craters of the Moon has a semiarid climate with hot, dry summers and cold winters. The annual precipitation from 1959 to 1982 averaged 42.6 cm (16.77 in), with greatest amounts in December or January of each year, mostly from snow. There were minor peaks in May or June of each year from rain. July and August are the driest months. Snow first falls in November, and except in dry winters it remains on the ground until at least April. Wind causes the snow to drift; drifts as high as 15 feet can persist well into May. Temperatures vary widely, both seasonally and diurnally. Aver age maximum monthly temperatures range from -1.7°C (28.9°F) to 28.7°C (83.7°F). Freezing temperatures can occur in any month. The prevailing southwesterly winds are most intense in spring.

The northern part of the monument is in the foot hills of the Pioneer Mountains; its higher elevation puts it in a different climatic regime. Snow remains longer in this area, and the total amount of precipitation is greater than that on the lava flows in the southern part of the monument.

AIR QUALITY

The air quality in Craters of the Moon Wilderness, which occupies 81% of the monument's total area, has been designated class 1 as defined in the Clean Air Act, as amended in 1977. Class 1 designation indicates the most stringent requirements for protection of air quality related values from adverse impacts. The air quality in the rest of the monument is class II. The dual designation resulted from the 1977 amendments to the Clean Air Act, in which class 1 designation was given to all national wilderness areas and memorial parks larger than 5,000 acres, national parks larger than 6,000 acres, and international parks in existence at that time. All other areas in the United States that did not exceed national air quality standards were designated class II. Because the wilderness adjoins the rest of Craters of the Moon National Monument, the entire monument is managed as a class I area; thus, the class II area benefits from actions taken to protect the air quality of the wilderness.

Air quality is of critical importance to visitor enjoyment, human health, scenic vistas, and preservation of natural systems and cultural resources. Most elements of a park environment are sensitive to air pollution. These elements, including vegetation, visibility, water quality, wildlife, historic and pre historic objects, and structures, are, referred to as "air quality related values." Notable air quality related values at Craters of the Moon are the visibility and the scenery. The health of visitors also is an air quality related value, as is vegetation. There is some evidence that gaseous air pollution may be adversely affecting some species of plants. Pollutants and their effects in Craters of the Moon National Monument are listed in table B-1.

TABLE B-1: POLLUTANTS AND THEIR EFFECTS

Visibility is of primary importance at the monument, which has more pristine visual air quality than any other NPS monitoring site in the continental United States. The Environmental Protection Agency uses Craters of the Moon National Monument as a baseline reference for visual quality. Even so, monitoring data indicate a trend toward deterioration. In the early 1980s it was assumed that a pristine airshed existed at Craters of the Moon until an initial analysis of visibility data for the monument demonstrated a significant decrease in visibility between 1982 and 1986.

To comprehend the geological phenomena that led to establishment of a national monument at Craters of the Moon, visitors must be able to see the Great Rift and the vast lava fields clearly. the average visual range at the monument varies from 93 to 125 miles in fall and winter and from 78 to 109 miles in spring and summer. Visibility is 174 miles or more about 10% of the time and less than 65 miles about 10% of the time. Integral vistas have been identified to the south and east of the monument, indicating that the visibility has a high value.

Smog can sometimes be seen entering the monument when prevailing winds are from the east and southeast. The probable source of the smog is the population centers at Idaho Falls and Pocatello.

Radioactivity is monitored because of the proximity of the Idaho National Engineering Laboratory. Radionuclide monitoring indicates that radioactivity is normal, with no carryover from the laboratory facilities. A chemical processing plant and a coal-fired steam generator at the laboratory also threaten the air quality at Craters of the Moon. Radionuclide monitoring indicates that radioactivity is normal most of the time, but spikes do occur that INEL officials attribute to their own activities.

Analysis of Craters of the Moon precipitation data during the 1982-1987 period revealed a mean annual average pH of 5.6 to 5.8. However, in 1989 the mean annual pH was 4.01 to 6.59. The data are inconclusive as to the acidity of precipitation at Craters of the Moon.

The Air Quality Division of the National Park Service has identified eight plant species and one mammal species that could serve as biological indicators of the monument's air quality; these are listed in the monument's resource management plan. The Air Quality Division also has reported red-banded tipburn damage to limber pines in the monument. This damage may have been caused by hydrogen fluoride. The source of the pollution may be a Pocatello phosphate fertilizer plant.

Symptoms of ozone injury observed on a few plants in the monument are dark stippling on chokecherry and black necrosis on aspen.

GEOLOGY

Topography

Craters of the Moon lies at the north edge of the eastern Snake River Plain, a broad, flat lava arc, concave to the north, which covers nearly 10,000 square miles of southern Idaho. It extends from the Yellow stone Plateau and the Teton Mountains on the east to the Oregon state line on the west. The Snake River borders the southern edge of the plain, which occupies almost a quarter of the surface of Idaho and contrasts markedly with the mountainous terrain that dominates the northern, central, and far southern parts of the state. The eastern Snake River Plain is essentially flat in this vicinity: vertical relief is a few hundred feet at Craters of the Moon and less than that elsewhere.

There are two distinct landforms in the monument: the foothills of the Pioneer Mountains in the north give way to the low relief of the lava flows in the rest of the monument. The monument's highest elevation, 7,729 feet above sea level, is in the Pioneer Mountains. Elevations gradually decrease from north to south; the lowest elevation is about 5,330 feet in southeast corner. Within the lava flows, cinder cones provide the greatest vertical relief. The highest cinder cone is Big Cinder Butte, which stands more than 700 feet above the surrounding plain. Nineteen other cinder cones are at least 100 feet high. The Great Rift is apparent from the linear alignment of the cinder cones.

Volcanic Features

The primary resource value of Craters of the Moon is the great diversity of basaltic features in a small area. Almost all the features of basaltic volcanism are visible at the monument.

Much of the volcanism of the Snake River Plain was confined to volcanic rift zones. A volcanic rift zone is a concentration of volcanic landforms and structures along a linear zone of cracks in the earth's crust. The Great Rift volcanic rift zone is a zone of cracks running approximately northwest to southeast across almost the entire eastern part of the Snake River Plain. The entire Great Rift is 62 miles long. The Craters of the Moon rift set is 34 miles long; 13 miles of this are in the monument (see the Lava Features map). The other rift sets that make up the Great Rift are, from north to south, the Open Crack rift set, 13 miles long; Kings Bowl, 6.8 miles; and Wapi, 11 miles.

The Great Rift is an example of basaltic fissure eruption. This type of volcanic activity is characterized by extrusion of lavas from fissures or vents that is relatively quiet in comparison with highly explosive eruptions such as the 1980 Mount Saint Helens eruption.

Where the Great Rift intersects the earth's surface, there is an array of cinder cones, lava cones, eruptive fissures, fresh-appearing lava flows, noneruptive fissures, and shield volcanoes. The Craters of the Moon, Kings Bowl, and Wapi rift sets have predominantly eruptive fissures (those from which volcanic products issued). The Open Crack rift set is a set of noneruptive fissures from which no lavas flowed. Craters of the Moon contains non- eruptive fissures as well as eruptive ones.

Of the more than 60 lava flows of the Craters of the Moon lava field, 20 have been dated; their ages were found to range from about 15,000 years be fore present (B.P.) to about 2,100 years B.P. The flows were laid down in eight distinct eruptive periods that recurred on an average of every 2,000 years. The Kings Bowl is the youngest of the Great Rift lava flows, slightly younger than the youngest Craters of the Moon lava flow. On the basis of recent eruptive history, the Craters rift set is due for another eruption within the next thousand years, perhaps as soon as within 200 years. Eruption is preceded by seismic activity. The resource management plan for the monument recommends establishment of a seismic monitoring system to predict impending volcanic activity.

Craters of the Moon lava flows are classified as aa, pahoehoe, or blocky pahoehoe. Aa lava has rough, jagged surfaces with sharp points. Pahoehoe, which is more fluid before hardening, spreads into sheets with smooth, glistening surfaces that are often twisted into ropelike wrinkles, pleats, and folds. A continued flow of pahoehoe lava may break the twisted surface into jagged blocks that resemble aa but do not have the sharp surface projections and spines characteristic of aa.

New basaltic lava generally has a dark brown surface. As lavas age and weather, the surface color may change. Disturbance to lava that alters the normal dark surface is evident because it ex poses the underlying oxidized area. Pahoehoe lava may take on a glossy, iridescent veneer due to chemical composition. The Blue Dragon and Green Dragon pahoehoe flows and the Vermilion Chasm are named for the striking lava colors in those areas. One area in the southeastern corner of the monument has been described as a "vast amphitheater whose towering walls are a riot of yellow, green, orange, brown, and black, with brick red and vermilion predominating."

Other volcanic features in the monument are cinder cones, spatter cones, vents, fissure cracks, collapse depressions, squeezeups, pressure ridges, bombs, tree molds, and lava tubes (see appendix C).

WATER RESOURCES

Surface water is extremely scarce at the monument. The single surface source is Little Cottonwood Creek, which flows from springs in the foothills of the Pioneer Mountains in the north unit. The flow of Little Cottonwood Creek disappears beneath the ground surface before reaching the highway.

Four springs in the Little Cottonwood drainage provide drinking water for the monument; this source is supplemented by two wells in the same drainage. The wells, each approximately 100 feet deep, tap a perched aquifer of unknown origin and size. There are only isolated occurrences of water on the lava flows.

The occasional existence of ice in the lavas is a seemingly strange phenomenon in the desert environment of Craters of the Moon, yet ice is often found in the holes and caves of lavas in areas that receive winter snow. Runoff water from snowmelt freezes in the depressions in cold weather and remains frozen because of the excellent insulating properties of the lava and because cold air moves downward, maintaining low temperatures.

The availability of water in water holes varies with seasonal precipitation, particularly snow. Some water holes in Craters of the Moon lava have gone dry since their occurrence was first noted. The water holes are important for wildlife living in the area of the lava flows.

Craters of the Moon is underlain by the Snake River Plain aquifer, one of the most productive in the western United States. The production from the aquifer and its depth beneath the surface of the monument are unknown, but wells drilled outside monument boundaries but near the monument have encountered water about 1,000 feet below the surface.

FLOODPLAINS AND WETLANDS

There are no floodplains in the monument. Areas of riparian vegetation are found along the Little Cottonwood Creek drainage in the north unit, and there are small areas around some of the springs in the north unit that could be considered seasonal wetlands under the definitions in the Federal Manual for Identifying and Delineating Jurisdictional Wetlands.

SOILS

Soil surveys have not been completed for most of the monument, but one was done for Carey Kipuka. Soils there are primarily windblown loess or soils that have developed from the area's basalt.

Soils in the north unit differ from those in the rest of the monument in origin and deposition, but lack of a soil survey prevents detailed analysis. In general, soils in the north unit and the kipukas are better developed than those in the rest of the monument. Little time has been available for soil development in parts of the monument that are covered by more recent lava flows. Soil accumulation depends primarily on accumulation of loess; this occurs most rapidly in crevices and cracks.

Soils in adjacent agricultural areas from which the vegetative cover has been removed are subject to wind erosion.

VEGETATION

Although much of the monument surface consists of barren lava flows, plant communities are surprisingly diverse (see the Vegetation map). The varied microhabitats within the lavas, variations in elevation from the lavas up to the foothills, the different aspects created by topography, and the riparian areas in the north end all contribute to habitat diversity. This has resulted in greater plant diversity than might be expected from a first glance at the seemingly barren lava.

The region is a part of the Great Basin floristic province. Day and Wright (1985) listed a total of 26 separate vegetation types in the monument (see appendix H). More than 300 vascular plant species are distributed among those 26 vegetation types.

Importance of Shrub Steppe Vegetation Type

Slightly more than 22% of the monument's total area is covered by shrubs (mostly sagebrush and antelope bitterbrush), grasses, or a combination of the two; the general vegetation type is called shrub steppe. This once was the common vegetation in southern Idaho, but grazing, fire, and agriculture have reduced incidence and altered the species composition of most areas. There is some concern that all native Idaho sagebrush grasslands are being reduced and altered from native condition. The national significance of low sagebrush/Idaho fescue and early low sagebrush/Idaho fescue vegetation types would be recognized officially if those biotic communities were designated national natural land marks, as has been recommended (see "Potential Special Designations" in the section on interrelationships with other proposals).

Stresses on Arid-Land Vegetation

On arid lands like those in the monument, vegetation is subject to heat, wind, salinity, floods, drought, infertile soils, and animal pressure. Human-induced stresses that can be added to the natural stresses are activities such as scraping, bull dozing, agriculture, water diversion, mining, over grazing, differential shrub removal, and the use of off-road vehicles. Such stresses are minimal in the monument, but they are present on the boundaries and beyond. The combination of human-caused and natural stresses can be devastating to arid-land vegetation, which is slow to recover from disturbance.

Vegetation in Specific Locations

The density of vegetation depends on the availability of soil. Where basalt rock is very young, the only soil available is what blows into cracks and fractures. As soil develops or is blown into crevices, vegetation takes hold. The depth of crevices, cracks, and depressions and the availability of favored microsites also determines what vegetation is present.

Lava Flows. The surfaces of the newest lava flows in the monument are devoid of vegetation except for lichens. Two of the vegetation types in the monument, low-density and medium-density lava flows, have low total plant cover relative to the rest of the monument. Low-density lava flows are found in about 58% of the total area of the monument, almost six times more than medium-density lava flows, which are in slightly more than 10% of the monument. The density of plant cover varies between types, depending on the age of the flow, but all types have similar species composition.

Kipukas. Kipukas are islands of vegetation developed on old lava flows and surrounded by newer flows. The native vegetation of some kipukas may have been altered by fire or livestock grazing be fore the monument was established. However, other kipukas in the monument were protected by rough lavas and may offer examples of the native Idaho shrub steppe habitat. Some exotic species have encroached into Carey Kipuka, but it is a relatively pristine remnant of native vegetation. Dominant kipuka vegetation includes three-tip sagebrush, big sagebrush, bluebunch wheatgrass, and needlegrasses (see appendix H for scientific names). The importance of these species varies broadly between and even within kipukas.

Cinder Areas. Cinder cones support three different plant communities, depending on aspect and successional stage. About 2% of the monument is cinder gardens, a distinct vegetation type. In the early successional stages, cinder gardens are colonized by species that produce spectacular spring wildflower displays. As soils develop on the cinders, antelope bitterbrush dominates shrub communities. Disturbances on cinder areas that cause depressions in the surface (such as vehicle tracks or footprints) may enhance plant establishment, but this often leads to unnatural plant patterns.

Limber pine are present on north-facing slopes where sufficient moisture is available. Limber pine occurs as a codominant species with antelope bitterbrush in three vegetation types, which together cover 7.1% of the monument. The limber pine stands appear to be favored mule deer fawning habitat in the southern part of the monument. At tempts were made in the 1950s to eradicate native dwarf mistletoe from the limber pine population. Numerous trees were pruned and poisoned, and 6,000 limber pine trees were killed. The program was stopped when managers finally realized that limber pine and dwarf mistletoe had coexisted here for thousands of years. The effects of this action have not been studied and are not understood; however, there was a change in the population and age structure of the limber pine forest.

North Unit. The north unit contains three vegetation types that are notable for the diversity they contribute to the monument: Douglas-fir/mountain snowberry, upland quaking aspen, and riparian. The three types cover only 0.3% of the monument, but they provide important wildlife habitat. The Douglas-fir/mountain snowberry type is found on relatively steep, north-facing slopes of older cinder cones and along Little Cottonwood Canyon. The upland quaking aspen type is in upland sites away from permanent stream courses. The riparian type is characterized by dense woody vegetation, proximity to a permanent watercourse, and a dense layer of tall forbs.

Noxious and Exotic Species

Nine species of noxious and exotic (alien) plants have been identified in the monument, including cheatgrass, common mullein, and Canadian thistle. Disturbed areas are particularly susceptible to invasion by exotics; consequently, most of the exotics are found in the developed north end of the monument. Cheatgrass, a common and widespread invader throughout the West, was introduced in the early 1900s when domestic sheep grazed the surrounding area. Common mullein has gained a stronghold along the dirt road and at the site of the old Martin Mine. Canadian thistle grows along Little Cottonwood Creek. The grass lawns of the monument's developed area are exotics that have been intentionally cultivated.

Leafy spurge is not known to be present in the monument, but it is present in Laidlaw Park and the Appendicitis Hills, both wintering areas for deer from the Craters of the Moon herd. This has caused concern that the deer may introduce the plant into the monument. Spray programs to control leafy spurge in areas north and south of monument boundaries are in effect at the Butte County agricultural extension office and the BLM's Idaho Falls and Shoshone districts.

Spotted and diffuse knapweeds are present in the monument along the highway corridor, and they are known to be in areas close to the boundaries. The state sprays the highway corridor annually.

Threatened or Endangered Plant Species

Idaho laws afford legal protection to state-listed threatened and endangered plant species.

No known federally or state listed, proposed, or candidate species of threatened or endangered plants are known to be in the monument. Near the boundaries of the monument are several species considered sensitive because of their rarity; these species may also be in the monument. To locate rare plant taxa, extremely detailed surveys of likely habitat are necessary, but the inaccessibility of much of the monument makes surveys difficult. Weather and moisture regime determine whether or not a plant will appear in a given year, so timing of surveys is critical. Appendix H contains a list of sensitive plant species found near the monument, with scientific names.

The meadow pussytoes grows in wet meadows along U.S. 20-26-93 between Carey and the western part of the monument. Obscure phacelia, a desert annual that had not been seen since 1969, was recently found again near the eastern boundary of the monument. It appears only at times when there is enough moisture. Both species are listed as endangered by the state and are category 2 candidates for the federal threatened and endangered list. (Category 2 candidate species are those that appear appropriate for listing as threatened or endangered but for which conclusive data on biological vulnerability and threat are not available to support a proposed rule.) No formal legal protection is attached to candidate species; however, NPS policy is to treat federal candidate species and state-listed sensitive species as if they were fully protected. (Also see appendix H.)

The Picabo milkvetch is known to grow near the southern boundary of the monument and from Picabo east to the Laidlaw Park area. It grows on sandy soils in association with three-tip and basin big sagebrush. This plant is on the Idaho Native Plant Society's list of species to be monitored for changes that could indicate that the populations or habitat are in jeopardy. It was formerly a federal category 2 candidate but is now listed as category 3 (see appendix H).

WILDLIFE

A total of 142 bird and 49 mammal species have been reported in Craters of the Moon. Five of the mammal species — grizzly bear, gray wolf, bison, porcupine, and bighorn sheep — are known to have been extirpated from the monument. However, a bighorn sheep was seen in the monument in the summer of 1990.

The most common animal species in the monument are horned lizards, mourning doves, sage grouse, killdeers, magpies, ravens, Clark's nutcrackers, common nighthawks, mountain bluebirds, great horned owls, golden eagles, bats, rabbits, chipmunks, grounds squirrels, pocket gophers, packrats, badgers, coyotes, mule deer, and pronghorn antelope.

Mule Deer

The Craters of the Moon mule deer herd, which has been studied intensively, is known to be very productive in comparison with other mule deer herds that have been studied. In addition to high productivity, the monument herd apparently is unique in having dual summer and winter ranges. Deer that are in the monument from April to November are known to winter on at least two separate ranges on private lands and BLM-managed land. Records of marked deer show that part of the herd migrates to winter range about 56 miles northeast of the monument near Moore, Idaho. Others apparently move about 45 to 65 miles south-south west across the Snake River Plain to an area north of Burley and east of Jerome.

The deer move back to the north end of the monument in April. Their summer movements are related to water requirements. Some remain in the north end in summer; the rest disperse among vegetated areas or make a loop into the southern part of the monument, returning to the north end in late July or early August, the hottest and driest time.

Hunting and winter mortality are the major sources of loss to the herd. The fall deer hunting season is an important event for the local community. Poaching on monument lands has been a problem, but this has been relieved somewhat through a vigorous and visually obvious enforcement program, an intense education program, better marking of monument boundaries, and cooperation with the local magistrate. Besides hunting mortality and poaching, important considerations in management of the herd are range condition and livestock trespass (which can affect range condition).

About 3% of the deer herd is killed annually by vehicles. Seventy percent of those kills occur in August and September, when deer summering in the north end of the monument cross the highway to forage on visitor center and employee residence lawns and drink from the sprinkler overflows.

Unusual Mammals

Three subspecies of small mammals endemic to the Snake River Plain were first identified in Craters of the Moon. A subspecies of the Great Basin pocket mouse was first taken from Echo Crater, as was the first specimen of a race of the pika (also see appendix I). As might be expected for mammals that live on lava flows, both races are characterized by darker fur than other races of the species. The first specimen of a subspecies of the yellow-pine chipmunk came from Grassy Cone.

Invertebrates

Of all invertebrates, only insects have been surveyed at Craters of the Moon. A comprehensive inventory of insects was completed in 1964-1967, when more than 2,000 species and subspecies were recorded from twelve stations. Of the 20 orders represented, most abundant were Hymenoptera (bees, wasps, and ants, 705 species), Diptera (flies, 521 species), and Coleoptera (beetles, 324 species). The type and age of the geological substrate and the variety and abundance of plants influenced the abundance of insects collected at a station. Little Cottonwood Creek station supported the greatest number of insect species. In lava habitats, old cinder cones yielded the most insect species; young aa flows supported the fewest. An inventory specific to the caves is needed.

Fish, Reptiles, and Amphibians

There are no fish in the monument. Two amphibian species, the western toad and the boreal chorus frog, have been reported in Craters of the Moon. Eight reptile species also have been reported: sage brush lizard, short-horned lizard, western skink, rubber boa, racer, Great Basin gopher snake, western garter snake, and western rattlesnake.

Threatened or Endangered Animal Species

Idaho laws afford legal protection to state-listed threatened and endangered animal species. The Idaho Department of Fish and Game also recognizes species that merit attention because of their present or future potential status. Species with restricted range, specific habitat requirements, and/or low numbers (which make them vulnerable to elimination from the state) may be classified as "species of special concern" to inform land managers and the public about the vulnerability of these species. Without special consideration, such species could become threatened or endangered. This classification does not provide any statutory protection.

Data on some species indicate that populations are declining or are less common than once reported, yet the species have not been classified by any agency into a category that affords special protection or consideration. These species are identified here as sensitive species; their populations should be monitored for changes until their status can be determined (also see appendix I).

Bald eagles, a federally listed endangered species, occasionally fly over Craters of the Moon, but they do not breed there or permanently inhabit the monument. Bald eagles winter in the vicinity of American Falls, south of Craters of the Moon on the Snake River.

The blind cave leiodid beetle, which is known to occupy lava caves in the monument, is a federal category 2 candidate species (see appendix I). Other category 2 federal candidate species that have been reported in the monument are the ferruginous hawk and the lynx. Swainson's hawk was formerly a category 2 candidate species but is now a category 3 species.

Ferruginous hawk, merlin, kit fox, and lynx are Idaho species of special concern. All have been observed in the monument except the lynx, which has not been reported in the monument since 1936.

Townsend's big-eared bats are known to inhabit Craters of the Moon. The eastern subspecies is listed as endangered; the western subspecies is a category 2 candidate species; and it is possible that the entire species will be proposed for listing, including the subspecies found in the monument. the bats inhabit caves, lava tubes, and abandoned mines throughout the monument; these habitats should be monitored.

The spotted bat has not been recorded from Craters of the Moon, but it may occur in the north end. This bat, a federal category 2 species, is very rare and is captured only when specific techniques are used. These methods were not used in the baseline vertebrate survey.

All birds except house sparrows, feral pigeons, starlings, and upland and migratory gamebirds are protected nongame bird species in Idaho. Nongame mammals protected in Idaho that are found in Craters of the Moon National Monument are pika, least chipmunk, yellow-pine chipmunk, golden-mantled ground squirrel, red squirrel, and kit fox.

CULTURAL RESOURCES

Prehistory

Evidence of human occupation in the vicinity of the monument dates from at least 10,000 years before present. the earliest recorded inhabitants were big game hunters. They were replaced by people who utilized a wider variety of plant and animal resources, but available resources could not support more than a few small bands of hunters and gatherers. During the late prehistoric and protohistoric periods, small bands of hunters and gatherers known as Northern Shoshoni occupied the area.

The most significant archeological sites for under standing the prehistoric inhabitants of the Snake River Plain are year-round living sites outside the monument; the monument area was occupied primarily in spring and summer. The nearest great density of cultural sites is in an area roughly a mile on either side of the Little Wood River, southwest of the monument. Much of the archeological material has been removed; few of the known sites now contain any archeological material.

Starting with a cluster of large archeological sites in the northwest part of the monument, the sites become smaller, fewer, and more thinly scattered as one proceeds south. the mass of lava prevented prehistoric peoples from moving north or south and inhibited east-west movement through the central and southeast parts of the monument. Except for sites near Little Cottonwood Creek and at the base of the Pioneer Mountains, known sites represent short periods of occupation. The presence of larger sites in the northwest part of the monument can be explained by easier travel at the base of the mountains than through the lava flows and more plentiful game and water in the mountains. the presence of only one site in the southeast corner, in the Vermilion Chasm-Fissure Butte area, suggests that this section was little used. the distribution of sites supports the theory that native hunters and gatherers came into the central and southeastern sections of the monument from the northwest, then moved south along the Great Rift, where travel was relatively easy.

The relatively small size of most sites in the monument reflects low population density. Five types of sites have been recorded in the monument: open sites, cave sites, rock structures, hunting blinds, and quarry sites. Open sites are the most common. Smaller open sites contained chipping material, implying that they were work stations used for short periods. Artifact assemblages indicate that the larger open sites were used as campsites. These larger sites are situated on the northwestern sides of prominent geological features such as spatter cones, cinder cones, and mountain slopes and thus were sheltered from weather and the prevailing southwesterly winds. All the larger sites are near intermittent streams or lava sinks containing water.

History

Southern Idaho was the domain of the Northern Shoshone and Bannock Indians until about 1800. The Shoshone had been driven west from Montana and the Dakotas by the Blackfoot. The Bannock from southern Oregon were a relatively small tribe who joined the Shoshone when larger groups were required, as for buffalo hunts.

Fur trappers were the only Euro-Americans inhabiting the Snake River area in the early 1800s. The Fort Hall trading post, which overlooked the Snake River (southeast of the present monument), was the only outpost for hundreds of miles. As the fur trading industry declined, Fort Hall became a welcome stop on the Oregon Trail for an estimated 200,000 emigrants bound for Oregon and California in the 1840s and 1850s. Big Southern Butte, east of the present monument, was a major land mark for Oregon Trail emigrants.

Aboriginal lifestyles remained relatively intact until gold and silver were discovered in Idaho in 1860, with an ensuing gold rush. Most mining in Idaho took place in the north part of the state, but placer and hydraulic gold mining were extensive along the Snake River. Euro-Americans came to dominate the area after the discovery of gold and establishment of permanent American settlements.

None of the historic fabric of the cutoff remains within the monument, and very little of the original cutoff is left outside the monument. The BLM has found the Goodale's Cutoff route eligible for nomination to the National Register of Historic Places. The portion of the cutoff route that is in the monument is listed on the National Register.

The volcanic regions appeared barren and useless until it was discovered that cattle and sheep could graze there. The livestock industries supplied meat and wool for mining communities and travelers along the Oregon Trail. The first irrigation ditches in southern Idaho were dug in the 1880s. With water, the land was fertile and productive, and farms and ranches sprang up. Idaho became a state in 1890. Huge federally funded irrigation projects resulted in settlement of most of the arable land in southeastern Idaho under the Carey Act, the Reclamation Homestead Act, the Desert Land Act, and the Stock Raising Homestead Act.

Historically, very few people, including Native Americans, ventured into lava flows. Robert Limbert entered the lava north of Minidoka in 1921, accompanied by W. L. Cole and a dog. The going was difficult, especially in aa lava. The explorers were unable to sleep on the rough surface. Cole's feet became blistered, and the dog's feet were so badly cut that the men carried it. The going was easier when they got to smoother pahoehoe flows, but the new problem was finding water. By following dove flights, they located snowmelt waterholes in the Great Rift. Limbert's photographs and reports were instrumental in obtaining protection of the area as a national monument in 1924.

The Bannock were more warlike than the Shoshone; they were willing to fight for their home land when settlers moved in. Native Americans were forced to give up most of their traditional lifeways when the Fort Hall Indian Reservation was established by treaty in 1868. Through intermarriage on the reservation, the Bannock and Shoshone cultures intermingled.

Indian raids in 1862 diverted Oregon Trail emigrants to the northwest. This route, known as Goodale's Cutoff after trapper Tim Goodale, follows the base of the Pioneer Mountains from Big Southern Butte through the north part of the existing monument. The cutoff was used as a stage route until 1906; some of it is now a dirt road.

VISUAL RESOURCES

To a casual observer, the landscape at Craters of the Moon may appear harsh and barren, but closer inspection reveals an astonishing variety of shapes, colors, and textures of the lava formations. In spring and summer, wildflowers display bright colors that contrast with the dark lavas. In winter a mantle of snow softens the harsh edges and brings new shapes and textures to light. The clarity of the air in the monument contributes to the visual quality of the vistas of the Great Rift to the south and the mountains to the northwest. Because there are few tall trees in most of the monument to block views, the volcanic features stand out in relief. The greatest diversity of visual resources is found in the spatter cones area, where the vertical relief of the Pioneer Mountains and the cinder and spatter cones gives way to the vast lava flows in the southern part of the monument.

VISITATION

University of Idaho Survey

The cooperative park studies unit of the University of Idaho conducted a visitor study at Craters of the Moon in the summer of 1988. The information in the following paragraphs was extracted from the complete report prepared by the cooperative park studies unit (Machlis, Dolsen, and Madison 1989).

Of the visitors contacted, 77% were visiting the monument for the first time, and 4% had visited more than five times.

Family groups made up 83% of the total; 44% of the groups consisted of two people (predominantly couples); 18% were groups of more than four people. The number of persons in a group ranged as high as 35.

Visitors aged 1 to 10 made up 13% of the total number; 17% were aged 62 or older. The number of visitors aged 26 to 61 were divided fairly evenly across those ages.

Visitors from foreign countries made up 19% of the persons contacted; 24% of the foreign visitors were from Canada. Most visitors from the United States were from Idaho and five other nearby states: California, Colorado, Oregon, Washington, and Wyoming.

Fifteen percent of the visitors were overnight visitors; of those, 79% stayed only one night; 18% stayed two nights. Visitors who stayed two hours made up 39% of the total; 28% stayed three hours; 12%, four hours; and 5%, more than four hours.

Most visitors who had stopped at the visitor center said they thought the exhibits and film offered were very useful to extremely useful. Those who went to the visitor center made up 79% of the total number contacted. The most popular other activities were stopping at overlooks and other turnouts to see the view or photograph the scene.

Visitors who hiked for less than one hour made up 46% of the total; 42% hiked for more than one hour. The most popular place to go for a walk or hike was the area of Big Crater and the spatter cones (81%), followed by the caves area (64%), the North Crater flow area (58%), Inferno Cone (56%). Devils Orchard (55%), North Crater cinder cone (54%), and tree molds (27%).

Visitation Statistics from Monument Records

Records kept by Craters of the Moon personnel over the past eleven years indicate substantial year-to-year variation in the number of visits, the number of tents and RVs using the campground, and the number of backcountry visitors (see table B-2). Some variation can be accounted for by a change in 1984 in the way vehicles were counted. Snow fall also is a major factor in annual fluctuations, since the time when snow begins determines when the scenic park road will be closed.

TABLE B-2: VISITOR STATISTICS 1979 - 1990

Visitation has averaged around 215,000 per year over the past decade. the number of visitors in creases gradually from spring to mid-July and remains at peak until mid-August. Peak visitation occurs between 10 a.m. and 4 p.m. each day; there is little variation with the day of the week. the campground often is full at night, and it is nearly empty by 10 a.m.

Since the staff has maintained a trail for cross country skiing, winter use has increased in deep snow years. The increase in winter use is relatively insignificant in terms of total visitation.

Table B-3 contains monthly visitation statistics from 1984 through 1990.

TABLE B-3: MONTHLY VISITATION, 1984 - 1990

Visitation Projections

Annual visitation has increased an average of 7% over the past decade, but the statistical division of the NPS Denver Service Center indicates that the erratic nature of annual visitation makes long-term forecasting difficult. A modest increase in visitation should be expected over the life of the general management plan. the statistical office has recommended that facilities be designed to accommodate from 285,000 to 300,000 visitors per year, or a peak of 63,000 to 67,000 during July and August.

EXISTING DEVELOPMENT

Most of the existing development at Craters of the Moon dates from the late 1950s and early 1960s, when extensive redevelopment was undertaken. Most of the management and visitor facilities are in a small developed area adjacent to U.S. 20-26-93. Other facilities are along the scenic loop road and across the high way in the north unit. The Month 1984 main developed area is constrained by the high way corridor, Sunset Ridge, and the North Crater lava flow to the south. There is virtually no room for expansion of the developed area; any new facilities would have to be fitted into the existing area.

Roads and Trails

The monument contains 2.37 miles of paved trails and 9.58 miles of unpaved trails. The paved trails are generally associated with the various waysides along the loop road.

Buildings and Facilities

The visitor center, which is combined with monument headquarters in a fairly small building of nondescript 1950s design, contains a lobby with an information desk and publication sales, a small exhibit room, and large public restrooms (see the Existing Conditions: Headquarters Area illustration). These facilities are all accessible to visitors with disabilities. In the management section are a small coffee room, a library, a restroom, and four office spaces, one of which is adjacent to the information desk in the lobby. In the era when this building was constructed, energy conservation was not a consideration. Since then there has been extensive renovation to improve energy efficiency, including enclosure of the entrance porch. Two parking areas with 50 spaces provide visitor parking; parking for the monument staff is available behind the building in the maintenance yard.

The 52-site campground contains a 130-seat amphitheater. There are two restrooms, each of which will accommodate one male and one female. An entrance station kiosk is located along the loop road where it passes through the campground (see the Existing Conditions: Entrance Station illustration). Vault toilets are located at the Tree Molds and caves parking areas and near the entrance station (the latter is primarily for winter use.) There are pit toilets in the group camping area.

Immediately behind the visitor center/headquarters building is a six-bay maintenance building. Parts of that building have been converted to offices. Fuel tanks and pumps are at the east end of the building. Vehicles are stored in the maintenance yard between the two buildings. A chlorinator building near the campground and a small storage building near the service road to the boneyard complete the management facilities.

The employee housing area east of the maintenance building consists of four one-room apartments, a duplex residence, and three single-family residences. If necessary, eight seasonal employees can be housed in the apartments, but this practice would violate current NPS housing policy.

Wood-burning stoves have been added to reduce heating costs in the family housing, and residences are being rehabilitated as funds become available. The major improvements being added are insulation and thermal windows. As appliances, storage cabinets, and flooring material are replaced and some spaces are remodeled, the family units are becoming more livable. It is questionable whether the apartments could be rehabilitated in a cost- effective manner to meet NPS housing standards.

Minor facilities in the monument are a weather station, a radio base station and repeater, air quality monitoring equipment, and temporary facilities (tents, solar shower, toilets) in the research camp in Little Cottonwood Canyon. A boneyard for the storage of materials is at the end of a short service road on the north side of Sunset Ridge.

Utility Systems

The local Rural Electrification Administration cooperative association furnishes power to several distribution points in the developed area. The monument maintains the distribution system beyond the meter. Telephone lines come into the monument from Arco. Power and telephone lines enter the monument overhead from the highway. Utilities are underground in the administrative area but over head in the campground.

Water, which is supplied by four springs and two wells (15 gallons per minute) in the northern part of the monument, is gravity-fed through a chlorinator and then stored in two concrete tanks (50,000 and 100,000 gallons) across the highway on the slope of Sunset Cone. From there the water is distributed to the visitor center, the campground, the group campground, and the housing areas.

Sprinkler systems are in place throughout the head quarters and residential sections to maintain the extensive lawn areas. At peak times, when lawns are being irrigated and visitor use is high, water consumption exceeds the supply from spring and well sources. There is a possibility that the supply of water could be exhausted in case of structural fires. Additional wells are being tested as a possible replacement for the spring sources.

Sewage for the utility area and the visitor center is handled by a 2,000-gallon single-compartment septic tank and leaching well. Approximately 150 feet of leach field extends through a section of the visitor center lawn. The residential area is served by a single-compartment septic tank and leaching well located in a fairly large cinder field away from the buildings. The campground restrooms are served by separate systems, each consisting of a septic tank and a concrete block open-joint leaching well. The vault toilets mentioned earlier are pumped by a contractor.

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