Red River EAWS Chapter 4 - Presettlement and Existing Conditions 4.0 Introduction This chapter describes presettlement and existing conditions and processes, and identifies important changes in the assessment area. The discussion of watershed conditions is organized into four broad resource categories: Physical includes discussions of the climate, air quality, geology, and soils of the watershed; Aquatic includes stream conditions and aquatic species population dynamics; Terrestrial includes vegetation and terrestrial wildlife populations, and Social includes the social and economic dynamics, activities, goals and objectives, and ideas and interests of the human populations within and near the watershed, and interacting with the watershed. Key findings in this chapter are also summarized in Chapter 5. 4.1 Physical Resources 4.1.1 Climate Climate is a basic element that affects soil development, stream flow regime and vegetation dynamics. As in the rest of northern Idaho, the Red River climate is influenced significantly by warm, moist Pacific maritime air masses and prevailing westerly winds. The southern-most and high elevation eastern portions of the Clearwater basin experience dryer and colder climate conditions typical of the northern Rocky Mountains (Bugosh 1999; Finklin 1977; N. Gerhardt, Nez Perce National Forest, personal communication February 2000). The Aleutian low and the Pacific high are weather systems that strongly influence local climates. The Aleutian Low dominates the winter months; bringing periods of heavy precipitation, mostly snow. The Pacific High dominates during the summer, resulting in warm and dry weather. Low-intensity, long duration frontal storms are common in fall, winter and spring, bringing fog, cloudiness and high humidity. High intensity, short duration thunderstorms accompanied by locally high winds commonly occur between May and September. Annual precipitation in Red River ranges from about 30 inches at the lower elevations to about 50 inches at the higher elevations (University of Idaho, 1993 and Abramovich, et al, 1998). Nearby long term weather stations are located at Elk City (elevation 4060 feet) and Dixie (elevation 5620 feet). There is also a SNOTEL site located at Mountain Meadows (elevation 6360 feet), just east of upper Red River. These stations are considered representative of similar elevations in Red River. There is also a seasonally- operated remote automated weather station (RAWS) at the Red River Ranger Station. It is used primarily for fire danger ratings. At Elk City, the annual precipitation for the period 1961-1990 was 30.03 inches. About 50% of the annual precipitation occurs from November through March, with much of it as snow. The wettest months are December and January, though May and June are also relatively wet due to a combination of frontal and convective storms. The driest months are July and August, respectively. Average annual air temperature at Elk City is 41°F. The warmest month is July, with an average daily temperature of 61°F, an average daily maximum of 81°F and an average daily minimum of 41°F. The coolest month is January, with an average daily temperature of 22°F, an average daily maximum of 34°F and an average daily minimum of Page 4-1 Chapter 4 – Presettlement and Existing Conditions Red River EAWS 10°F. During the growing season, eight years out of ten can be expected to have 11 consecutive days when temperatures do not drop below freezing (Abramovich, et al, 1998). At Dixie, the annual precipitation for the period 1961-1990 was 29.32 inches. Precipitation patterns are similar to Elk City, though a deeper snowpack tends to accumulate due to cooler average temperatures. Average annual air temperature at Dixie is 36°F. The warmest month is July, with an average daily temperature of 56°F, an average daily maximum of 75°F and an average daily minimum of 37°F. The coolest month is January, with an average daily temperature of 17°F, an average daily maximum of 30°F and an average daily minimum of 4°F. During the growing season, eight years out of ten can be expected to have 2 consecutive days when temperatures do not drop below freezing (Abramovich, et al, 1998). At Mountain Meadows, the average annual precipitation for the period 1961-1990 was 47.6 inches. The snow water equivalent (amount of water stored in the snowpack) typically peaks around May 1, with the average being 26.5 inches. 4.1.2 Air Quality Air quality associated with Red River is generally considered good to excellent. Local adverse effects result from occasional wildfires during the summer and fall, and prescribed burning during spring and fall. Smoke from wildland fires and prescribed fires usually drifts eastward and eventually into Montana. The western boundary of the Selway Bitterroot Wilderness, a Class I airshed under the Clean Air Act, is about 15 miles east of the Red River watershed. Restrictions on Nez Perce Forest prescribed fires have been imposed in the past because of adverse effects on air quality in the Bitterroot Valley of western Montana. Smoke produced by wildland fires and prescribed fires in upwind airsheds, including southern Idaho and eastern Oregon, has also impacted this area in the past. Locally, all major canyons are subject to temperature inversions, which trap smoke. These inversions may occur and affect smoke dispersal in topographic basins at different scales such as the South Fork Clearwater Canyon or the Red River Canyon. Temperature inversions can occur anytime during the year, but are most common in the fall. Historic Based on fire history information, the range of natural variability in Red River probably ranged from very clear and clean during the non-fire months (November – May) to hazy and smoky for extended periods during the fire months (June – October). Current Current Red River air quality during non-fire months is probably close to the range of natural variability. During the fire months, air quality is probably clearer and cleaner and outside the natural range of variability. The exception to this is when large wildland fires are burning. Under current policy, most wildland fires are suppressed. Therefore, the amount of smoke has been greatly reduced from previous historical levels. Of the six national ambient air quality standards (NAAQSs), particulate matter (PM) is the only one applying to prescribed burning. This standard is based on the amount of particulate matter of a particular size (less than or equal to 10 microns), produced by a given activity, averaged over 24 hours. The Environmental Protection Agency (EPA) has accepted PM2.5 as a new standard, but states have yet to adopt this standard. PM2.5 represents approximately 80% of the PM10 produced by prescribed burning. Guidelines for regional haze, a visibility requirement under the Clean Air Act, are currently under development. Page 4-2 Chapter 4 – Presettlement and Existing Conditions Red River EAWS Prescribed Fire vs. Wildfire Using prescribed fire will reduce impacts to air quality when compared to the same area being burned by a naturally occurring fire. By monitoring fuel and weather conditions, a time can be identified to implement prescribed burns when smoke dispersal is optimal, the number of acres consumed can be controlled and fuel consumption can be limited. Under wildland fire burning conditions, nature selects the weather and fuel conditions under which the burn takes place. Often more fuel is consumed, because the fuel conditions are drier, and wildland fires often last for extended periods. As a result, impacts to air quality can last for extended periods with greater volumes of smoke. Wildland fires occur during the warmest and driest months of the year (June – October); this is also when the Pacific high dominates the weather patterns and temperature inversions are common, causing smoke to pool in basins. 4.1.3 Geology The Red River watershed is located in the southern Clearwater Mountains portion of the Rocky Mountain physiographic province. The topography is generally one of gently rolling hills especially near ridge tops. Slopes near river and stream margins are steep in some locations. The lower six miles of Red River are confined in a narrow rocky gorge. In the remainder of the watershed numerous, isolated rock outcrops exist and some are spectacular. Map 10 displays the Geologic Groups for Red River. The geologic history of the Red River watershed is complex. In general, older rocks tend to be in the central and western part of the watershed while younger rocks are found in the eastern part of the watershed. The mix of rock types and their interrelationship is not predictable. Only site-specific review will allow determination of potential concerns and impacts. The fracturing and weathering has produced a geologic condition that should be carefully considered when planning management activities in the Red River watershed. Much of the granitic rock is deeply weathered and highly erosive when exposed. In addition, the rock formations in the watershed have been deformed and fractured by faulting, specifically along the 14-mile Blanco shear zone, and by the emplacement of the Idaho batholith. These factors may present situations that need to be evaluated for each specific management proposal that would create surface disturbance. For further information and recommendations see Red River EAWS, Geology Field Review, Jo Ellis, District Geologist, February 5, 2003. 4.1.4 Soils Soils are the biologically active zone at the interface of earth and atmosphere. Soils regulate movement and storage of energy, water and nutrients. Soil physical properties, such as bulk density and texture, affect water holding capacity, hydrologic response, and surface stability. Soil erosion reduces soil productivity and the eroded material may be delivered as sediment to stream channels. Soil compaction alters runoff patterns and soil water availability and can reduce vegetation growth potential. Soil disturbance can also alter slope hydrology and runoff peak flows and timing, affecting channel morphology as well as sediment regimes.