1 FOREST ROADS AND AQUATIC ECOSYSTEMS: A REVIEW OF CAUSES, EFFECTS, AND MANAGEMENT PRACTICES NCASI Forest Watershed Task Group

1.0 INTRODUCTION The impacts versus values of forest roads have been the subject of recent debate in the United States. Forest roads historically have had substantial adverse effects on streams. Depending on how they are managed, roads can continue to impact streams today. The objectives of this paper are to describe 1) why roads are critical fo r effective land management; 2) the impacts of historical road construction practices; and 3) how legacy and current effects of roads can be systematically evaluated and managed to reduce impacts to acceptable levels. In 1997, the debate over roads intensified as a result of the Interior Columbia Basin Ecosystem Management Project (ICBEMP) Assessment of Ecosystem Components in the Interior Columbia Basin (Quigley and Arbelbide 1997). This assessment found that increasing road densities (combined with the activities associated with road s) are correlated with declines in anadromous salmonid species. However, the ICBEMP report also noted that the component contributions (causes) of effects associated with roads could not be identified, and that they were therefore “forced to use roads as a catch-all indicator of human disturbance.” Since that time, a number of road mileage control and reduction efforts have developed. The Forest Service and Bureau of Land Management (BLM) have accelerated road obliteration activities. The Federal Roadless Area Initiative would prohibit constr uction of new roads in “roadl ess” areas of Forest Service and BLM lands (impleme ntation is currently in suspension). The Forest Service has also developed a Road Analysis procedure to assess road conditions and management needs (USDAFS 1999). The National Marine Fisheries Service’s (1996) “Matrix” includes road density as a screening criteria for considering whether proposed federal actions will have adverse effects on threatened and endangered species. The US Environmental Protection Agency has suggested that road density be used as a means of regulating water quality within its Clean Water Act Section 303(d) regulation of Total Maximum Daily Loads (USEPA 1999). The focus of this paper is the interaction of fo rest roads and aquatic eco systems, and it is written from the perspective of private, for-profit, fo rest management busine sses competing in the international forest products market. We discuss only direct impacts of roads, not secondary effects such as providing access to sportsmen or poachers – these are not road management problems, but people management problems. Most of the information provided herein is from the western U.S. While some of the details may differ slightly for other regions, the fundamental issues and principles that apply to the West remain applicable across the country. 1.1 Working Definition of a Road for this Paper The definition of a road may seem self-evident. However, definitions have been constructed that confuse rather than clarify the relationships of roads and streams. For example, USDA Forest Service (Gucinski et al. 2000) recently offered this definition: Road “ecosystems” are built and maintained by people . . ., characterized by open fluxes of energy and matter, and a2 predominance of respiration over photosynthesis – that is, they are heterotrophic and highly subsidized systems. The goal of this paper is to clarify road and stream interactions, and an uncomplicated definition serves this purpose. For this paper: Roads are smooth-surfaced corridors for truck and automobile transportation

. The corridor includes the entire disturbed “road prism” comprised of the road cutslope, the road tread, the road fillslope, and an y additional widening for ditche s, berms, or other disturbed surfaces that are structural parts of the road right-of-way. Figure 1 is taken from the Forest Road Management Guidebook (ODF 2000) and diagrams the road prism and its components.

Road prism N atural hillslope

Cutslope

Ditch Surfacing

Fillslope

Toe of fill

N atural hillslope

Figure 1. Road Prism Structural Features

1.2 Road Types Individual road segments are built and mainta ined as part of a network that forms a transportation system. The construction standard and use of any given road segment depends on its function within the system.

Primary roads are the most heavily traveled roads and generally originate from paved county or state highways. They are generally surfaced with rock (“graveled” roads), are built for use throughout the year, and easily accommodate two-way traffic. The locations of many of these modern-era truck roads were establis hed during development of the initial (often3 railroad-based) transportation system into entire watersheds; for this reason, and others as discussed more fully in Section 1.6, they are often located on gentle grades near streams.

Secondary roads generally depart from primary roads and may or may not be graveled. The road location may have been determined at any time over the last 100 years. These roads are commonly closed during at least part of the year. Two-way traffic is usually accommodated by turnouts spaced along the route.

Temporary roads are generally unsurfaced, that is, they usually are not surfaced with gravel, although gravel surfacing of temporary roads is a common practice in particularly wet areas of the West Coast and Alaska. At least since development of state forest practices rules and more environmentally sound practices in the 1970s, these roads are generally closed to traffic immediately after completion of log hauling and/or silvicultural activities such as slash disposal, thinning, and tree planting. Active measures are generally also taken to re-establish vegetation on the road surfaces and to allow the road to maintain itself in a condition of low erosion and low to no sediment delivery to streams. 1.3 Why Do We Need Roads? Roads are essential for all land management strategies other than wilderness (Burnett 2001). They provide access for:

Fire control – Forest roads play two key roles in fire control. First, they provide access for fire fighting manpower and machinery. Second, they provide firebreaks. The fire protection plan developed to address repeated and catastrophic wildfires in the Tillamook State Forest in western Oregon is based on a dual purpose road system that provides 1) rapid access to hazardous areas; and 2) a pre-constructed system of firebreaks that can be accessed rapidly by fire control personnel and machinery (ODF 1993).

Grazing – Forest roads are commonly used to disperse cattle and sheep throughout summer range and to collect them in the fall.

Timber management – Forest roads are an essential asset for active timber management. They provide cost-effective a ccess for timber stand inventory, forest health assessment, selection and marking of trees to be harvested, timber harvest personnel and machinery, tree planting stock and tree planting personnel, and the means for removal of harvested trees from otherwise remote forests via truc ks. Alternative access, such as using helicopter yarding, can be used effectively, particularly for difficult and unstable landscapes. However, even helicopters require some road system, because they are econo mically limited by how far they can fly from harvest areas to landings on roads. Economical flying distances for helicopters vary depending on the value of the logs being flown, but rarely exceed 1 mile downhill. Flying distances must be substantially shorter if helicopters are forced to lift and fly loads uphill to landings, because of the increased time and fuel needed to lift the loads.

Recreation – Although not generally constructed directly for this purpose, forest roads provide access for a multitude of recreational activities, including recreational driving (sightseeing), camping, fishing, hunting, berry picking, and others. For example, over4 200 million recreation activity days per year were made to federal lands in the ICBEMP assessment area, 45% of which were for sightseeing (Quigley and Arbelbide 1997). Forest roads also access points of departure for trail uses such as hiking, horseback riding, and ATVs. In fact, points of departure for wilderness access are often found on low volume forest roads.

1.4 Economics of Road Networks Although roads are essential to land management for forest products and other uses such as recreation, there remain legitimate concerns about where roads should be located and how many roads are necessary. The number of roads required for active forest management in an area is determined by both environmental and economic considerations. Once environmental requirements such as avoidance of unstable slopes and troublesome stream crossings are assessed and constraints on potential road locations are understood, log yarding costs are compared to road construction and maintenance costs. Yarding of logs with cable systems is commonly used on steep slopes for both environmental and cost considerations, but the difficulty increases rapidly with increasing yarding distance and dist ance between roads, particularly in steep and/or highly dissected topography. As a result, cable yarding costs increase rapidly and nonlinearly with increasing yarding distance. Similar tradeoff considerations also apply to ground-based tractor skidding operations often used on gentler terrain. Road construction costs can vary widely, depending on the road standard (see discussion below) and site conditions (see discussion above). Road construction costs range from less than $10,000 per mile on gentle terrain remote from streams, to over $200,000 per mile on steep slopes where the design requires features and practices that prevent landslides and delivery of sediment to streams (Scherer 2000; Clark et al. 2000). Typically, as slopes become steeper and as environmental hazards such as landslides or ro ad surface erosion and sediment delivery to streams increase, road design requirements to address these hazards become more and more expensive (Furniss et al. 1991). In some situations, environmental hazards may be so great that design and construction requirements become prohibitively expensive, or hazards cannot be addressed irrespective of design. Alternative but more expensive yarding systems, such as long-reach skyline cable systems or helicopters, may then be necessary. In the ideal and theoretically pure economic calculation, additional road is not justified when the cost of building more road exceeds the savings due to reduced yarding distance. However, complex terrain, land ownership patterns, exis ting roads, and/or environmentally unacceptable locations often dictate road spacing, which in turn often requires road density to increase beyond an economic optimum. 1.5 Road Management Road building, upgrading, and maintenance are basic to commercial forestry operations and require a significant part of company operatin g budgets. They are crucial in the active management of the land and movement of forest products off the land. Because of their high value and potential environmental consequences, road assets are constantly managed. Management involves seven key steps:5Transportation system planning – Roads must be located to serve their intended transportation system objectives while at the same time meeting environmental constraints and requirements. These dual objectives provi de a classic case where neither objective can be completely optimized, and a satisfactory solution is sought where both economic and environmental goals can be adequately met. Harvest methods, anticipated traffic, operating speeds, and safety requirements must be considered. All of these influence road width and alignment, which affect areas of disturbance and environmental consequences.

Route reconnaissance and location – Based on the constraints identified in the transportation system planning process, the next step is to determine specific road locations. Alternative routes are carefully reviewed in the office a nd in the field using all available information, including past performance of existing roads in the area or nearby similar areas, aerial photos, soils data, geology, topographic maps, stream locations, and fisheries information.

Road design – This is the step where various measures to control potential adverse effects of roads on watershed processes are considered. Road design involves translation of field location survey and other data into specific plans to guide construction. Practices for control of surface runoff, erosion, and delivery processes are prescribed at this stage. In addition, future maintenance needs are considered to assure stability and economical use of the completed road; if regular maintenance cannot be assured, this must be accounted for in the design so that erosion and delivery processes are adequately controlled.

Road construction – The best planning and design is useless unless it is incorporated into the finished product (Megahan 1977). Competent supervision of the construction phase is required. Important erosion control practices to consider during construction include:

- Keep slope stabilization work as current as possible with road construction.

- Thoroughly clear and grub brush, timber, stum ps, and other woody debris from roadbed and fill areas to prevent potentially serious surface and mass erosion problems.

- Spread cleared vegetation and woody mate rials over the soil surface below fills to enhance the sediment trapping and “buffer” characteristics of the slope below the road.

- Keep stream disturbance to an absolute minimum and avoid it altogether during high flows.

- Limit the work area during construction to sm all sections to limit exposure of disturbed area to erosion forces in the event of adverse weather, and keep installation of relief drains current with sub-grade construction.

Maintenance – Road maintenanc e is critical in order to provide continued access and control environmental impacts. Properl y maintained roads have a stable surface and an operating drainage system that drains water from roads as quickly as possible onto the forest floor instead of directly to streams. Poorly maintained roads are most subject to periodic blockage or “failure” as transportation systems due to both surface erosion and mass wasting events, primarily during floods. Erosion and sediment delivery associated with such failures can be extreme. In addition, roads produce chronic surface erosion impacts, particularly where poorly located and maintained. Hazard and impact assessments and implementation of6 carefully designed road system maintenance plans can significantly reduce or even eliminate these impacts (Furniss et al. 1991; ODF 2000). Detailed examples of impact assessment and road construction and maintenance plan effectiveness are provided in Appendix B (Section B.5).

Upgrading – Upgrading activities are similar to maintenance. With upgrading, old roads built to lower standards with lower sensitivity to environmental issues can be brought up to current standards as forest harvesting occurs in adjacent areas or where priority environmental concerns are identified (ODF 2000; WFPB 2000).

Closure – Roads that will not be used again in the near future are often closed. This is an extremely cost-effective measure in cases where environmental concerns do not require obliteration. At some time in the future, the road may be reconstructed with minimal disturbance. A key to road closure is achieving self-maintaining drainage. In some cases, for example where there is significant landslide hazard, old roads may be totally removed from the landscape. This practice is commonly called obliteration. 1.6 Transportation System History The system of forest roads in the western US today is the result of over 100 years of human habitation and use of forest la nds. Access for timber harvest a nd mining were the major driving forces resulting in the first forest roads, and the location, design, construction, and maintenance of forest land access has changed dramatically over the last 100 years. Widespread logging began in the coastal and inland areas of the West in the mid-1800s and early 1900s (Sedell et al. 1991; Bonner School 1976). The earliest logging occurred in locations adjacent to the ocean, lakes, and rivers where logs could be felled, rolled, or dragged with horses or steam engines (steam donkeys) directly to the water (Sedell et al. 1991). As water-adjacent timber ran out, additional water-based horse and st eam/cable logging systems were used. These systems relied on chutes, flumes, and splash dams to move logs downhill and/or downstream. Horse skid roads, chutes, and many flumes were located in streams, on streambanks, or in riparian zones. The adverse effects of these early logging practices on stream and channel characteristics are well documented (Sedell and Luchesa 1982; Sedell et al. 1991). Effects on erosion and sediment delivery processes are less well documented. However, we know that logs were commonly dragged downhill directly to streams without erosion control practices, and large quantities of sediment were undoubtedly delivered to streams in watersheds logged with these early methods. Splash damming depended on channel simplification and removal of large wood and boulder obstructions, as well as artificial and repeated flooding followed by dewatering of channels. Channel beds and banks were scoured by log-laden flood waters. Use of these practices was widespread, and in some river systems continued as late as the 1960s (Bisson et al. 1992; Sedell et al. 1991). Water-based logging systems were often coupled with railroad logging systems as they were developed (Robbins 1988). Although some rail routes were located on or near ridgetops, most were located in valley bottoms and often encroached on the streams, particularly in narrower7 headwater canyons. Railroad logging practices of that era relied on cable logging systems, and ground-lead and downhill yarding systems were common. With the advent of more powerful equipment, water and rail-based logging were slowly replaced by logging truck and logging road-based systems, beginning in the 1930s (Robbins 1988). Both tractor and cable yarding systems were used to move logs to landings where they could be loaded onto trucks. Logging roads often occupied old railroad grades, but roadbeds had to be widened, and in contrast to railroads, truck traffic s ubstantially increases ra tes of erosion from the travelway (Reid and Dunne 1984). During this era of ground-based, downhill logging systems, harvest-related erosion rates have been estimated to exceed background levels by two to three orders of magnitude (McGreer et al. 1996). 1.7 Interactions with Aquatic Ecosystems Roads can undoubtedly affect streams and interact with aquatic ecosystems. The linkages of roads to hydrologic and erosional processes and effects are illustrated schematically in Figure 2.

Erosion Processes Hydrologic Processes ROAD EFFECTS

Connectivity Channel crossings Gullies Overland flow Fish passage (obstructions at crossings) Surface (fines) Mass (fines & coarse)

Water in stream Peak flows Scour & fill Sediment in stream Water quality Fish Channel morphology Aquatic habitat Channel Encroachment

Riparian vegetation Shade LWD

Figure 2. Linkages Between Forest Roads and Beneficial Uses8 Managers must address four major potential impacts of roads on aquatic ecosystems. A brief introduction to each of the effects follows. They are discussed in detail in Sections 2.2 through 2.4, and a discussion of management practices and systems that control such effects can be found in Appendices B and C.

Hydrologic effects – Roads can change watershed hydrology by intercepting subsurface flow from hillslopes and by generatin g overland flow from the road prism. Water may be routed directly to streams or onto adjacent hillslopes, with the potential effect of changing peak flows (increases or decreases). If increases in peak flows are large enough, there is potential for affecting channel morphology and dependent biological systems.

Erosion and delivery of sediment to streams – Both fine and coarse sediment can be delivered from roads to streams. Runoff from road surfaces often contains fine sediment (particles of sand size and smaller, usually defined as 2 mm and smaller). This fine sediment can impact aquatic ecosystems by filling interstitial spaces in streambed gravels and/or by increasing turbidity levels. Roads can also be a source of coarse sediment that originates through mass erosion (landslides). Large quantities of coarse sediment introduced to stream systems during floods can contribute to channel scour, deposition, avulsion (out-of-bank change of stream course), and other major adjustments in channel morphology.

Channel encroachment – Roads located in valley bottoms, especially in narrow valley bottoms, may directly impinge on channels. This may result in increases in channel gradient and reduced opportunity for overbank flow, as well as decreases in desirable habitat area or alterations in habitat characteristics (e.g., shade, opportunity for large woody debris recruitment). Road stream crossings can result in channel changes immediately downstream of the crossing due to the effects of focusing water through a narrow culvert (in comparison to stream width).

Fish passage – Road culverts may block fish passage where they are too high above the base channel for fish to jump or where the gradients and velocities in the culverts are too steep and rapid for fish passage. 1.8 Changes in Road M a nagement The result of over 100 years of forest access is that most of the roads needed today for management of private lands have already been built. However, much of today’s existing road system was designed and built to standards and in locations that would not be used if the system were built “from scratch” today. Road effects, when aggregated at the landscape scale, are dependent on road design and road location, and assessment of these effects must consider the proportion of old roads to new roads that incorporate improved engineering design (Gucinski et al. 2000). In many cases, major reductions in environmental impacts are possible through relocation and improvement of old roads, and such improvements are being aggressively pursued (Furniss et al. 1991). However, these improvements are not accomplished easily or cheaply. Based on an understanding of road impacts and the technology that has developed to address these impacts, forest managers have changed their approach to managing roads. Some examples of these changes are:9Road location – Roads used to be located in the easiest position to construct them, which was often on floodplains and near streams. Today, new roads tend to be located in mid-slope and ridgetop locations where channel encroachment, riparian impacts, and delivery of fine sediments are minimized. Although old roads near streams often caused a disproportionately high share of landslides due to placement on steep inner gorge slopes, managers learned that mid-slope roads can also contribute to landslides. Managers now must identify inherently unstable slopes and either avoid these locations entirely, or construct roads using design and construction techniques that have been demonstrated to be effective at preventing landslides for the specific circumstances encountered (Miller et al. 2001).

Road construction – Historically, the development of powerful bulldozers allowed costeffective construction of deeply excavated, wide roads in mid-slope locations. This practice contributed to many of the landslide problems that have been widely observed throughout the West and reported in th e literature. Roads were commonly engineered and constructed using “balanced” cuts and fills that led to wide ro ad prisms, large cut a nd fillslopes, and large volumes of excavated materials. The excavat ed materials had to be disposed of, often by “sidecasting” these materials onto steep slopes below the road travelway or by building the road fills with them, and were often poorly compacted. These techniques contributed to large numbers of avoidable failures (Gardner 1979). Today, hydraulic excavators, which can precisely excavate and place materials (Bechman 1980), have almost universally replaced bulldozers for road construction on mountain slopes. Roads are now designed to minimize cut and fill volume by constructing roads no wider than necessary and by fitting them as closely as possible to the natural topography (Gardner et al. 1978).

Road drainage design – Historically, road drainage systems were designed with the sole objective of protecting the structural integrity and utility of the road; effects on the environment were of little concern (Gardner 1979). Large volumes of water were often allowed to collect from long lengths of road and were then channeled directly into streams, a practice that contributes to delivery of large volumes of sediment. While protection of road integrity remains impor tant, environmentally effective road drainage has developed as an equally important objective during the past 30 to 40 years. Now roads are often fit more closely to the topography, with rolling grades pr oviding natural drainage, rather than the long uniform road grades used in the past. Roads are purposefully designed to discharge water frequently, to minimize length of direct delivery, to discharge at locations chosen to minimize delivery of water and se diment to streams, and to minimize concentra tion of water that could contribute to slope gullying or landslides. Drainage of existing road systems can also be redesigned to substantially reduce sediment delivery, often to only a fraction of the original amount, by increasing the frequency of relief drains or other techniques such as those described in Appendix B (Section B.5.4) and Appendix C (WFPB 2000; McGreer et al. 1998; Packer and Christensen 1964).

Culvert size – Another major improvement in road design and drainage involves the size of culverts placed in streams at road crossings. For decades, most western states required that culverts be designed to pass only the 25 year flood – a design that is statistically predicted to have a 50% probability of overtopping within 17 years of installation. Today, the minimum design requirement of most state forest practices rules is 50 to 100 years (IDL 2000a; ODF 1994; WFPB 2000).10Road maintenance – Road maintenance used to be a matter of keeping roads trafficable and efficient for transportation. Today, maintenance is recognized as a critical component of both environmental and business performances of roads. Current road maintenance practices executed to minimize surface erosion and ma ss wasting include surface grading and maintenance of road gravel to prevent rutting; ditch cleaning to insure that water remains in ditches and does not erode the ditch or the running surface; monitoring, cleaning, and replacement of relief and stream crossing culverts; monitoring and grading of rolling dips; and treatment of cut and f illslopes to encourage and re tain protective vegetation.

Road use – Roads used to be open to access at all times. Today, access control through the use of gates is commonly practiced to minimize road surface damage during wet periods and reduce erosion and sediment delivery. The results are often substantial; prevention of ruts in road surfaces alone can reduce erosion by approximately 50% (Burroughs and King 1989). Long-term road treatments such as closure, abandonment, and even obliteration are becoming more common. Reduction of sediment delivery to streams can be particularly significant where roads in highly erosive mate rials are located adjacent to streams. For example, in the Lower East Branch of the LeClerc Creek watershed of northeastern Washington, closure, rehabilitation, and relocation of 1.5 miles of the 12.7 mile road system will eliminate 80% of the sediment delivery in the sub-watershed (McGreer et al. 1997; Stimson Lumber Company 1999). Appendix A provides a synopsis of the discussion of Sections 1.6 through 1.8, at least in qualitative terms, through a historical example of the early evolution of logging transportation systems away from downhill and water-based system s to mid-slope truck-ba sed systems, and the major reduction of impacts to stream system s that results. Appendix B (Section B.5) provides examples of transportation system analysis that quantifies sediment delivery reduction due to road relocation and improved maintenance and design. 2.0 PATHWAY ANALYSIS OF ROAD/AQUATIC ECOSYSTEMS Roads are a vital part of forest management and an important asset. Yet they have important interactions with aquatic sy stems that must be managed to achieve environmental objectives. The broad changes in road management practices that managers have enacted are a result of the gradual development of these environmental objectives over the past 40 years or more. Ultimately, forest managers must determine how much change in existing road systems is sufficient to meet aquatic goals and how to achi eve those changes most efficiently. Answering these questions involves two elements. First, technical assessments must be framed that connect road management activities with fish population response. This is called critical pathway analysis. The challenge for managers is to understand critical pathways well enough to effectively address the variability that exists in forest watersheds so that they don’t have to resort to inefficient (and often ineffective) one-size-fits-all solutions. Pathway analysis and its utility are described in this section, followed by a detailed discussion of the technical assessment steps within pathway analysis that allow identificati on of management impacts on watershed processes, streams, and fish. This is followed by the second element: “how much is enough” – the interaction of management practices (specific actions) w ith management systems (the decision process11 selecting specific actions) and how pathway analysis can be and is being used in forest road management systems. Pathway analysis involves connecting management with an understanding of how watersheds interact with aquatic populations (fish, amphibians, etc.). In an effective pathway analysis, there is an exchange of information between key levels, including those shown in Figure 3. 1 This illustration focuses on the major effects of roads: sediment and runoff delivery.

Management System (Directs activity at landscape scale)

Management Practices (BMPs at the site scale)

Watershed Processes

Sediment and Runoff Delivery

Channel and Water Column Conditions

Habitat

Populations Figure 3. Elements of Critical Pathway Analysis

Although this approach may appear complex, pathway analysis is made efficient by understanding which questions need to be answered and which ones are less important. By focusing efforts on information that answers key cause and effect questions, a sound technical approach is provided without incurring a great deal of unnecessary effort, and without oversimplifying the problems at hand. Although the understanding of watershed processes is incomplete, managers and scientists do understand a great deal about the variability of watersheds and roads, and have developed tools to manage this complexity. Moreover, industry foresters and watershed specialists continuously work in the watersheds that they manage, and have opportunities to view processes within them through time and under extreme conditions. These observations add to the collective understa nding of watersheds and fit within the critical pathway approach, allowing for systematic adjustment of practices where necessary to prevent undesirable land management impacts. Cause and effect (critical pathway) linkages between forest roads and aquatic systems are developed by tracing how roads influence watershed processes (runoff and erosion) in their vicinity and by determining and quantifying how water and sediment are delivered from roads to streams and subsequently routed through stream channel systems. Channel responses are then interpreted in terms of possible effects on stream habitat and fish populations.

1 At the lowest level of Figure 3, making the link to populations necessarily involves factors outside the watershed

of local concern (e.g., ocean conditions, commercial harvest, sport fishing, etc.), but such factors are beyond the scope of this paper, which focuses on the role of roads.12 Contrasting with cause/effect critical pathway anal ysis are approaches that attempt to regulate road construction effects with coarse indirect indices such as road density. Such approaches do not provide efficient means of managing potential effects on downstream beneficial uses, because they do not link cause and effect, and therefore do not efficiently allocate finite road management resources to the specific problems (causes) that must be addressed to prevent and solve problems (effects). These subjects are discussed in more detail in Section 2.7. The role of management systems and management practices – the steps shown at the top of the critical pathway in Figure 3 – are then reviewed. Following that is a summary of the effects of roads on hydrologic and erosion processes in the vicinity of the road prism and how these effects ultimately link to stream habitat and fish populations (beneficial uses). This knowledge of the cause and effect linkages between roads and beneficial uses provides a feedback framework to help determine how road related environmental effects can be systematically managed within acceptable levels. This hierarchy for illustrating pathway analysis lends itself to visualization of the adaptive management approach; when channel, habitat, or population objectives are not achieved, the steps at the top that managers control – management systems and management practices – are readjusted. 2.1 Management Practices and Systems Applying appropriate road practices in forest watersheds to reduce negative water quality impacts requires two elements: a set of management practices for roads which can effectively reduce water quality impacts; and a management system which ensures that the right practices are applied in the right places. The manageme nt system is used to select and implement practices chosen from the set of management practice options. The selected practices have been called Best Management Practices (BMPs). BMPs are determined to be the most effective and practicable means of controlling pollutants at levels compatible with environmental goals. However, management systems now go beyond what can be considered identification of traditional BMPs. These systems not only addre ss current management activities, but may also identify and treat hazards and impacts that occur due to historic activitie s, as well as address existing watershed hazards. 2.1.1 Management Systems Management systems identify which practices will be applied at which sites. An effective management system identifies the site characteristics and hazards unique to the area of concern, and selects appropriate practices to address these hazards. Management systems include state forest practice rules or BMP-based systems, watershed or landscape analysis systems, and special issue management systems such as habitat conservation plans or the Oregon Plan for Salmon and Watersheds. Timber companies have also developed their own road management systems that incorporate one or more of these approaches. An effective management system for roads requires several steps. These include an inventory of road and stream conditions, identification of road sections requiring practices to bring them into acceptable condition, identification of effective practices and costs, development of priorities and a schedule of work, appropriate timeframes for implementation and completion of necessary tasks, implementation monitoring, periodic inspection to determine performance of implemented13 practices, and training to update personnel assessing roads or implementing control practices. A number of systems already in place or currently being developed to accomplish these steps are described in Appendix B, along with examples of the effectiveness of several of these systems. 2.1.2 Management Practices There are a variety of management practices that can be used to reduce impacts from roads, with emphasis most often placed on those designed to control sediment from roads and to reduce changes in runoff. Sediment control practices for roads can be categorized as practices that reduce surface erosion from the road surface, cu tslope, or fillslope; practices that avoid landslides; and practices that reduce delivery of sediment to streams. Runoff control practices generally attempt to limit the area of road that directs runoff to stream channels. Specific examples of techniques designed to accomplish each of these goals are described in Appendix C. Additional examples can be found in the references cited in Appendix C, in the Handbook for Forest and Ranch Roads (Weaver and Hagans 1994), and in various state forest practice guides and regulations (IDL 2000a, 1996; Logan 2001; WDNR 1997; WFPB 2000).

2.2 Road Effects on Watershed Processes 2.2.1 Hydrologic Processes A number of hydrologic processes affected by roads can result in increases in the volume and/or rate of runoff. These changes in runoff are manifestly from the effects of vegetation removal, as well as from physical disturbances caused by construction of the road. 2.2.1.1 Vegetation Removal Removing vegetation from the road right-of-way has effects similar to clearcut timber harvest, including reduction of evapotranspirational water loss from the soil, reduction of interception of rain and snow by tree canopies, and increases in snow accumulation and melt rates (Dunne and Leopold 1978; Troendle 1983; USACE 1956). These effects are permanent for the road running surface (if they are not closed or abandoned and allowed to revegetate), but are more temporary for road cuts and fills that may revegetate over time. Changes in these vegetative effects due to harvesting have been found to be significant in many experimental watersheds where clearcut harvest has affected 20 to 100% of watershed area. However, roads occupy only a small fraction of watershed area (typically 2 to 12% – see Table 1). As a result, streamflow effects due to roads have generally not been detected. In those studies where streamflow effects due to roads have been detected, the authors generally attribute thes e to road disturbance effects on soil infiltration, subsurface and surface flow interception, and concentration and discharge of water from road drainage structures rather than to effects associated with canopy removal (Burroughs et al. 1972; Harr et al. 1975; Jones and Grant 1996; King and Tennyson 1984; Megahan 1972).14 Table 1. Road and Harvest Area Reported for Experimental Watersheds

Study Location Watershed area (acres) Road
area Harvest
area Horse Creek central Idaho 1 50-370 2-4.5% 21-33% Alsea Oregon Coast Range 2 40-175 3-12% 20-100% Oregon Cascades Oregon Cascades 3 25-250 3-11% 25-100% H. J. Andrews Oregon Cascades 4 250-29,000 5-6% 22-25% H. J. Andrews Oregon Cascades 5 250 8% 22% Caspar Creek northern California 6 1,000 4.5% 60% 7

1 King 1989; King and Tennyson 1984 2 Krygier and Harr 1972; Harr et al. 1975 3 Jones 2000 4 Beschta et al. 2000; Jones and Grant 1996; Thomas and Megahan 1998; Wemple et al. 1996 5 Rothacher 1970 6 Keppeler and Ziemer 1990; Wright et al. 1990; Ziemer 1981 7 60% of timber volume removed 2.2.1.2 Effects of Road Disturbance Construction of the road prism has additional effects that increase the volume and rate of runoff. Two processes in particular are reduced inf iltration and interception of subsurface flow. Reduced infiltration is most apparent on the road tread, and the effect can reduce infiltration rates by an order of magnitude or more compared to undisturbed forest floor. For example, Reid and Dunne (1984) found an average infiltration rate of 0.5 mm/hr on a graveled road tread surface, with estimates ranging from 0.3 to 0.8 mm/hr. In contrast, infiltration rates in conifer forest are typically in excess of 10 mm/hr (Dunne and Leopold 1978; Johnson and Beschta 1980). Road cut interception of subsurface flow can be very erratic; it is highly dependent on specific site conditions, and can also be affected by harvest on hillslopes above the road. For example, a road in the Pine Creek watershed in the Idaho Batholith intercepted 8.4 inches of subsurface flow from watershed area above the road, which represented about seven times the amount of direct runoff from the road surface (Megahan 1972). In the Lochsa River drainage in north central Idaho, a road located several hundred yards downslope of the drainage divide intercepted on the order of 7 to 8 acre-feet of subsurface flow per day per mile of road and on the order of 5 to 6 acre-feet of overland flow per day per mile of road during the peak snowmelt season in early June (Burroughs et al. 1972). Conversely, a road in the Olympic Mountains of Washington intercepted no subsurface flow; there was no cutbank seepage and no base flow in road ditches (Reid and Dunne 1984). In central Idaho, Megahan (1972) found that one section of road intercepted more than three times as much water per unit length of road as another road section. The combined effect of vegetation removal and disturbance due to roads on streamflow volume and distribution characteristics is discussed in detail in Section 2.5.3. 2.2.2 Erosion Processes and Delivery of Sediment to Streams Roads increase erosion because of both effects on hydrologic processes and changes in other site factors that influence erosion rates. Although effects vary greatly depending on specific site15 conditions, both surface and mass erosion rates often increase with road construction in mountainous areas. 2.2.2.1 Surface Erosion Surface erosion is defined as the downslope m ovement of individual soil particles, including inter-rill (sheet erosion), rill, and gully erosion. The degree of compaction, soil exposure, slope length, and slope gradient are the main factor s controlling the rate of accelerated erosion (Wischmeier and Smith 1965). During construction of forest roads, long continuous lengths of soils are purposefully excavated, exposed, and compacted. In some cases, these surfaces convey water directly to streams (Packer and Haupt 1965; Pearce undated). Surface erosion is chronic on forest roads, with rates varying with site conditions, rainfall eros ivity, and time since construction. Surface erosion can also be episodic in the case of culvert failures (plugging) at channel crossings or at cross drains, usually during large storm events, where water is diverted onto and erodes road surfaces. The particle size distribution of material eroded from road surfaces is generally smaller than that from mass erosion, which includes both fine and coarse materials found throughout the depth of the failure. Particle sizes of sediments resulting from surface erosion are small (sand and smaller), and become even smaller depending on the downslope runoff process, sometimes appearing solely as washload (turbidity). For example, Bilby et al. (1989) found that 80% of road surface erosion sediment was finer than 0.004 mm, and none was greater than 0.25 mm. In contrast, Gonsior and Gardner (1971) found that landslide materials generally contained less than 20% finer than 0.05 mm, and 15 to 45% was coarser than 2.5 mm. A number of factors contribute to increased erosion from forest road surfaces. Soil erodibility is increased due to disturbance effects of road construction and vehicular traffic. Slope gradients are increased on cut and fillslopes. Erosion can be increased through increased raindrop impact due to loss of intercepting vegetation, increased overland flow on road surfaces, and flow concentration in drainage ditches or road ruts. Finally, erosion is enhanced on clean, bare road surfaces due to lack of surface protection by vegetation and/or duff. Surface erosion rates from roads are typically at le ast an order of magnitude greater than rates from harvested areas, and three orders of magnitude greater than erosion rates from undisturbed forest soils. For example, estimates of road surface erosion rates in California, Idaho, and Washington are generally in the range of 10 to 100 tons/acre/year (Cline et al. 1981; McCashion and Rice 1983; Vincent 1979; WFPB 1997), with extreme estimates as high as 480 tons/acre/year in Washington’s Olympic Mountains (Reid and Dunne 1984). In contrast, typical harvest-related rates of surface erosion that have either been measured or used in modeling procedures range from 0.5 to 5 tons/acre/year (McCashion and Rice 1983; Cline et al. 1981; Potyondy et al. 1991). Natural surface erosion rates in undisturbed forest lands range from zero to approximately 0.005 to 0.1 tons/acre/year (Clayton and Megahan 1997; Cline et al. 1981; Dunne and Leopold 1978). Recent research indicates that long-term “natural” erosion rates may be much higher than previously thought, due to infrequent catastrophic events such as extreme wildfires (Kirchner et al. 2001).16 Most of the factors leading to increased surface erosion from roads are manageable by adjusting road design features, employing erosion control practices, and performing proper road maintenance. For example (also see Appendices B and C):

Avoid locating roads on steep hillslopes – The road prism disturbed width is three times as large on a 60% slope as on a 30% hillslope (Megahan 1977, 1976).

Limit road slope – A 13% road gradient produced more than three times as much erosion as a 6% road gradient (Vincent 1979; Luce and Black 1999); the Universal Soil Loss Equation (USLE) predicts that the erosion rate approximately triples as road gradient doubles (Dunne and Leopold 1978).

Install and maintain frequent drainage features – Installation of additional road drainage relief culverts by itself is pr edicted to reduce sed iment delivery to streams by 25 to 85% in eleven watersheds ranging in size from 5,490 to 69,850 acres (Luce and Black 1999; McGreer et al. 1998).

Rock the road surface – Graveled tread reduced erosion by 77% over native surface (Burroughs and King 1985; Luce and Black 1999).

Treat cut and/or fillslopes – Stra w applied to fillslopes at a rate of 1 ton/acre reduced fillslope erosion by approximately 60% (Burroughs and King 1989). Dry seeding and hydromulching are effective erosion controls on erosive granitic cutslopes (Megahan, Wilson, and Monsen 2001).

Trap eroded sediment – A filter windrow at the toe of the fills lope reduced sediment leaving the fillslope by approximately 85% (Burroughs and King 1989; Cook and King 1983).

Provide subsurface drainage in high hazard areas (French drains).

2.2.2.2 Mass Erosion Mass erosion (or mass wasting) is defined as the movement of material en masse, primarily under the influence of gravity, and in the case of roads is almost always episodic. Large-scale mass erosion of roads occurs most commonly as debris avalanches, debris flows, and slumps (Benda et al. 1997; Swanston 1991). Small-scale mass erosion also occurs on roads, especially cutslopes, from piping, micro-scale debris flow, and dry ravel. The eroded material includes all particle sizes at the site for the depth of the failure, and is therefore coarser than that for surface erosion (Gonsior and Gardner 1971). Roads have typically been the predominant cause of increased rates of mass wasting associated with forest management, with acceleration factors commonly found to be in the range of five to one hundred times greater for roads than for harvesting (Swanston and Swanson 1976; McClelland et al. 1997). Several factors cause increased mass erosion due to roads. Slope gradients are increased on cut and fillslopes. Subsurface water flows can be altered, due to both cutslope interception of subsurface water and changes in water flow on and below fillslopes a nd hillslopes below the road. Loss of deep-rooted vegetation on the road right-of-way reduces hillslope stability. Landslide risk can also be increased by mistakes or oversights during road construction, such as17 leaving organic debris in fills, over-steepening cut or fillslopes, or failing to recognize local high hazard situations. These factors often work in co mbination with each other in ways that are not well understood. However, several studies report that the road failures most damaging to streams occur primarily from fill and sidecast fail ures that develop into debris avalanches on slopes steeper than 70%, and secondarily from culvert and stream crossing failures (Bush et al. 1997; Fiksdal 1974; Gonsior and Gardner 1971; Gray and Megahan 1981; Megahan et al. 1978; McClelland et al. 1997; Sidle et al. 1985; Skaugset et al. 1996; Swanson and Dyrness 1975; Jones et al. 2000). Rates of mass wasting va ry greatly across the landscape, de pending on climatic, geologic, and topographic factors as well as factors associated with management practices. Rates of debris avalanche occurrence associated with forest roads in westside studies conducted in the early to mid-1970s ranged from 25 to 344 times the rate in undisturbed forests (Benda et al. 1997; Sidle et al. 1985). Further demonstrating the variability of results, studies in Oregon, Idaho, and Washington have reported that anywhere from 27 to 72% of all observed landslides were associated with roads, 10 to 77% were associated with harvest, and 9 to 63% occurred naturally (Bush et al. 1997; Dyrness 1967; Fitzgerald and Clifton 1997; Gresswell et al. 1979; McClelland et al. 1997; Megahan et al. 1978). In terms of mass failure volume, similar studies show 34 to 53% of total failure volume related to roads, 6 to 63% related to harvest, and 3 to 46% occurring naturally (Dyrness 1967; Gresswell et al. 1979; Ice 1984). In other words, roads are associated with most failures and failure volume in some stud ies (in fact, most studies), but certainly not in all studies and all locations. 2 For areas of the inland northwest, few landslide rate studies are reported in the literature. However, Megahan and Kidd (1972) reported that roads built in small headwater basins in the 1950s and early 1960s in the central Idaho batholith increased rates of mass wasting by a factor of over 400, but actual numbers of road failures in relation to natural rates were not reported. In another study in Idaho, Megahan et al. (1978) report that roads constructed prior to 1979 accounted for 56% of all landslides that occurred in a three year period that included an extreme flood in 1974. More recently, in contrast to Megahan and Kidd’s (1972) results, McClelland etal. (1997) conducted a survey of all failures greater than 25 cubic yards in volume in nonwilderness areas of north central Idaho’s Clearwater River basin, including large areas of batholith. Table 2 summarizes their findings. McClelland et al. (1997) shows that roads had double the rate of mass wasting relative to natural rates, with smaller effects on landslide volume and volume delivered to streams. Even smaller increases in rates of mass wasting have been reported for several analyses conducted as part of watershed assessments in eastern Washington, Idaho, and western Montana (McGreer et al.

2 In contrast to roads, acceleration facto rs due to harvest range from 2 to 9 over undisturbed conditions in westside

studies, with even lower increase factors for some eastside studies (McGreer et al. 1998). For example, in the H. J. Andrews Forest in western Oregon for the period 1950 to 1974, Swanson and Dyrness (1975) found a road-related landslide rate of 4.8 slides/mi 2 /year, 0.47 slides/mi 2 /year from clearcut areas, and 0.15 slides/mi 2 /year in undisturbed forest. In terms of slide volume, the same study found approximately 19 tons/acre/year from road-related slides, 1.7 tons/acre/year from clearcuts, and 0.6 tons/acre/year in undisturbed forest. These results are reflective of roads constructed prior to most forest practices acts and are consistent with other studies in western Oregon, Washington, and British Columbia that report road-related slide volumes varying from 2 to 100 tons/acre/year, 0.2 to 2 tons/acre/year from clearcuts, and undisturbed rates of 0.1 to 0.6 tons/acre/year (Ice 1984; Sidle et al. 1985; Swanson and Grant 1982).18 1998), where landslide rates and hazards are commonly lower than those that occur in areas west of the Cascade crest (Megahan et al. 1978).

Table 2. Clearwater Basin Landslides Reported by McClelland et al. (1997) Natural

slides Road-related slides Harvest-related slides % of Total Number 29 58 12 % of Total Volume 59 36 5 % of Delivered Volume 71 25 4

Consistent with the general findings of the landslide studies reported in the literature, McClelland et al. (1997) reported that most road failures were fill failures on steep slopes and were generally associated with poor construction, maintenance, and/or drainage practices. Road fill failures, including fill failu res associated with culvert blockages and diversions, are the predominant form of road-associated mass wasting (NCASI 1985; Furniss et al. 1991). Avoidance of hazardous locations and attention to road fills and drainage are often noted as means of preventing failures from roads that are to be constructed in the future. Insufficient stream crossing culvert capacity, often compounded by debris obstruction, has also been noted as an important cause of culvert failure, resulting in overtopping or diversion from streambeds onto unstable road fills, with associat ed mass wasting and severe surface erosion and gully erosion events (Furniss et al. 1991; McClelland et al. 1997). Although the forest practices rules of California, Oregon, Idaho, Montana, and Washington now call for stream culvert design capacity based on the 50 to 100 year flood event, many roads were built when the requirements were based on the 10 to 25 year event. Thus there is a legacy of undersized culverts that remain potential site-specific erosion hazards on some roads. In virtually all the studies reviewed for this paper, the majority of failures observed are from roads built years ago in locations and with construction methods which later became unacceptable and/or illegal, and thus road syst ems pose significant potential for legacy effects. As practices have improved and as old roads eventually stab ilize, this potential can be expected to decrease; as early as 1984, Ice (1984) noted evidence from westside studies that rates of road failure were decreasing. In a summary of impacts of the 1996 floods in Oregon, Robison et al. (1999) reported that “current road management practices are reducing the size of road associated landslides, as well as the number of landslides.” McClelland et al. (1997) also reported that following intense rain-on-snow precipitation during the 1996 floods the rate of failure of roads built in the 1970s through the 1990s was approximately half the rate of failures of roads built in the 1950s and 1960s. The risk of mass erosion on forest roads can be reduced through careful road design and location, proper design of fills, adequate groundwater drains, and control of volume and location of runoff water. Some of the guidance often reported includes:19Avoid locating roads on steep hillslopes – Most failures occur on hillslopes greater than 70% (Gresswell et al. 1979). The road prism disturbed width is three times as large on a 60% slope as on a 30% hillslope (Megahan 1977, 1976).

Use full bench/endhaul road construction – In stable sandstone soil types in western Oregon, sidecast road construction and moderate road gradients resulted in approximately 40 times more slides per mile of road than full bench/endhaul roads of steeper gradient. The difference in less stable sandy/gravelly soils was approximately a factor of two (Sessions et al. 1987).

Install and maintain frequent drainage feat ures and size culverts appropriately (Copstead and Johansen 1998; Gonsior and Gardner 1971; Furniss et al. 1991).

Compact fills (Gonsior and Gardner 1971).

Provide subsurface drainage in high hazard areas (French drains). 2.2.2.3 Delivery of Water and Sediment to Streams Reduction and control of road runoff and erosion is important to help maintain road trafficability, as well as to reduce the potential for downslope delivery of water and sediment. The amount and timing of delivery of water and/ or sediment from roads to streams depends on the type of geomorphic processes involved, local site conditions, and the nature of road location, design, and maintenance; the latter three are factors that can be managed. Runoff from roads generally follows one of four pot ential pathways: infiltration back into the hillslope below the road with no delivery to stre ams; direct delivery at channel crossings (Paths A, B, and C in Figure 4); direct delivery thro ugh gullies formed below relief drains (Path D in Figure 4); or indirect delivery via overland flow below the road. Direct delivery at channel crossings is the most common and most rapid form of delivery, and occurs where roadside ditches (Path B in Figure 4) and/or road tread runoff (Path C in Figure 4) run directly to the stream crossing structure, whether it is a culvert, bridge, or ford. Delivery at stream crossings is controlled partly by the spacing of relief drains; i.e., if relief drains are located only a short distance from the actual crossing, less road surface area will deliver water directly to the crossing.

Gullies can be formed below road ditch relief drains by erosion at the drain outlet or by headward extension of the stream channel system. Gullying (Path D in Figure 4) results in moderately rapid delivery to streams, and is primarily a function of the length of road contributing to the drain and the hillslope gradie nt below the outlet (Wemple, Jones, and Grant 1996; Croke and Mockler 2001). Gullies can be caused by excessive runoff through the relief drain, steep gradient in the cross-drain, a perched drain outlet, and/or lack of armoring below the drain outlet. Gullying can be controlled by reducing the distance between relief drains and by employing energy dissipaters or armoring below drain outlets (ODF 2000).20 stream hillslope

cutslope

ditch

road surface fillslope A B

C

D ditch relief culvert

stream crossing culvert

Figure 4. Water and Sediment Delivery Paths From Roads (A) subsurface flow interception (B) flow through road ditches to streams (C) flow along road surface to streams (D) flow through gullies to streams

Overland flow below roads is the slowest form of delivery, and is the least likely to deliver substantial quantities of wa ter or sediment to streams, due to the slowing effects of intervening vegetation and other obstruc tions on the hillslope that trap at least a portion of the road discharge (Elliott et al. 1997; Megahan and Ketcheson 1996). The prominence of direct delivery and gullying is documented by research done in western Washington and Oregon. These studies found that 42 to 66% of road drainage points discharged to hillslopes with no delivery to streams, 28 to 35% of drains delivered directly to streams, and 17 to 28% delivered via gullies (Bilby et al. 1989; Bowling and Lettenmaier 1997; La Marche and Lettenmaier 1998; Wemple, Jones, and Grant 1996). More importantly, however, these same or similar studies have found that 17 to 35% of the total road mileage contributes sediment to the stream system (Bowling and Lettenmaier 1997; McGreer et al. 1997), or conversely, 65 to 83% of the road mileage did not contribute sedime nt to streams. Such examples confirm the ubiquitous “80-20 rule,” in this case, 80% of the problems come from 20% of the roads. This reveals a key principle: reducing the road mileage that discharges to streams – not merely reducing road mileage or road density – reduces both the quantity of sediment that reaches streams and any potential effect that roads may have on peak flows. Comprehensive assessments21 of road erosion and road drainage to streams can be highly effective in reducing road impacts, and examples of such assessments and their implementation are provided in Appendix B (Section B.5). Sediment delivery from roads due to surface erosion is a function of the volume of water discharged from the road, the volume of sediment carri ed by this water, and characteristics of the path that the water/sediment solution travels (Megahan and Ketcheson 1996). Sediment from surface erosion near stream crossings is carried directly into the channel, and thus has the greatest chance for delivery. Likewise, most sediment travelling through cross drains into gullies connected to a stream is supplied to the stream, although deposition en route is possible. Elsewhere, sediment in runoff moving downslope as overland flow is transported at low velocities, and thus is likely to be deposited en route (Brake et al. 1997; Ketcheson and Megahan 1996). Annual delivery of surface erosion sediment to streams from a given road segment can vary from zero to tens of tons, depending on such factors as the specific delivery route (stream crossing vs. gully vs. discharge to hillslope), contributing roadlength, road gradient, hillslope gradient, road surfacing (native surface vs. graveled vs. paved), cut and fillslope vegetative cover, and so on (Elliot et al. 1997; Haupt 1959; WFPB 1997). Sediment delivery to streams from road surface erosion can be controlled through several mechanisms that operate synergistically. Erosion and sediment control practices are discussed in Appendix C. Sediment supply from mass erosion is episodic, as is the erosion itself, and thus delivers relatively large volumes of sediment over short periods of time. Sediment supply from mass wasting is strongly influenced by a number of factors:

Type of mass erosion process (slump vs. debris avalanche vs. debris torrent) – Slumps and earthflows, which typically penetrate deeper into soil mantles, generally are slower moving and less likely to deliver sediment than shallow rapid failure s such as debris avalanches and debris flows, particularly when the latter become channelized in headwater draws and streams. For instance, in the H. J. Andrews Forest of western Oregon, only 14 out of 47 observed events during the winter of 1964/1965 caused channel scour, but those 14 events represented 64% of the total eroded volume from all 47 events (Dyrness 1967).

Location in the road prism (cut vs. fill) – Road cut failures, which in many areas occur more commonly than fill failures, often fall to the running surface and are partially or totally trapped there. For instance, from 1974 to 1976 in the Clearwater National Forest of north central Idaho, 66% of observed road failures originated from cutslopes but only 47% of the total failure volume came from cutslope failures, i.e., cutslope failures tended to be smaller than fillslope failures, and mo st cutslope failures deposited on the road tread and failed to reach streams, whereas half of the total fill failure volume was delivered to streams (Megahan et al. 1978). During the winter of 1964/1965, 32% of road failures in the H. J. Andrews Forest originated from cutslopes, but nearly half of those cutslope failures deposited entirely on the road tread (Dyrness 1967).22Slope, valley, and channel cond itions below the road – Most failures occur on hillslopes greater than 70% gradient (Gonsior and Gardner 1971; Johnson et al. 2000; Sessions et al. 1987). Road segments near ridgetops (within 100 m) have lower frequency of mass failures; segments located mid-slope have higher frequency of failures and are more likely to reach streams sources; segments located in valley bottoms also have high frequency of failures (Wemple 1999). If failures become debris flows within channels (sometimes called debris torrents), they are likely to continue downstream until channel gradient becomes less than 6%, a tributary junction angle greater than 70  is reached (Benda and Cundy 1990), or where slopes are gentle and channels unconfined (Johnson et al. 2000). As a result, debris flows often reach larger fish-bearing waters.

Particle sizes delivered to streams from mass er osion are similar to the size distribution of the material at the slide initiation site, whether natural soil or road fill, and can include all sizes from clays to boulders. Because mass wasting generally delivers large volumes over short time periods and can also deposit large particle sizes, sediment from mass erosion can have substantial effects on channel morphology over relatively long periods of time (Hogan and Schwab 1991; Megahan et al. 1980). As discussed in Appendix C, most landslides associated with roads can be prevented by avoiding hazardous locations and by employing a number of construction and maintenance practices that have been demonstrated to be effective.

2.3 Channel Encroachment Effects

Channel encroachment due to construction of ro ads directly adjacent to and within stream channels is a legacy of past practices. State regulations and forestry BMPs no longer allow roads to be constructed in these locations (WFPB 2000; IDL 2000a; MDHES 1997; ODF 1994). Existing roads in valley bottoms, especially in narrow valley bottoms, may directly impinge on the channel and result in increased channel gradients, reduce the opportunity for overbank flow, and directly decrease desirable habitat area and characteristics (e.g., reduced stream shading or large woody debris recruitment). Although no longer a construction consideration, these potential effects should be addressed when considering road maintenance and closure plans. 2.4 Fish Passage Effects Road culverts may block passage of juvenile and adult fish where they are too high above the base channel for fish to jump or where the grad ients and velocities in th e culverts are too steep and rapid for fish passage. Passage barriers have been found to be common in a number of road system inventories, potentially resulting in substantial loss of habitat and population impairment (Dent and Allen 2000; Hoffman and Sylte 2001; ODF 1999a). Both general and detailed procedures for judging the adequacy of culvert design and conditions for fish passage are provided by the Oregon Department of Forestry (ODF 2000; ODF 1999b) and the Washington Department of Fish and Wildlife (WDFW 1999). A number of active efforts are also under way to inventory and correct unacceptable culvert conditions (ODF 2000; Plum Creek Timber Company 2000; Stimson Lumber Company 1999).23 2.5 Road Effects on Channel and Water Column Conditions Increases in water or sediment inputs to streams can affect physical channel conditions and water quality. However, the natural range of variability of stream parameters such as flow, suspended load, or bedload can be very large, and detecting the potential effects of roads within that wide range can be difficult. For example, in July 1992, a thunderstorm dropped 2.8 inches of rain in a gaged sub-watershed of Mica Creek in northern Idaho. Streamflow increased from 0.3 cfs to 10 cfs over a 1 hour period, producing a flood estimated to be between a 2 and 5 year return period, accompanied by substantial bedload movement. 3 Even in this heavily instrumented watershed, detecting road effects is very difficult given the degree of natural variability of the system. Although individual management activities can increase sediment loads and deposition within streams and can affect streamflow, more severe effects can result from the simultaneous or cumulative effects of several sources (NCASI 1999) – effects which are more likely to express themselves at the watershed scale. Changes in sediment supply and runoff from roads may or may not be manifested at the watershed scale (i.e., beyond merely locally and just downstream of the input site), depending on the magnitude and timing of the change in relation to watershed conditions. 2.5.1 Suspended Sediments Sediment concentrations depend on the amount of sediment relative to streamflow, with additional dilution occurring downstream due to additional inflow of water from tributaries and other sources (NCASI 1999). Forest streams in many regions (but not some parts of the South) are considered sediment limited, so increases in fine sediment available for transport in the stream can lead to increased suspended sediment concentrations. Suspended sediment concentrations are highly variable, varying by as much as two orders of magnitude in undisturbed watersheds even under similar streamflow conditions (Beschta 1978; Fredriksen 1970; King and Gonsior 1981). This degree of inherent variability or “noise” in the system often makes it difficult to detect the effects of road construction, especially with increasing distance downstream from the sediment source. 4 Even in small catchments, effects on sediment concentrations can be difficult to detect, and the effects decrease over time as surface erosion rates decrease, often to the point of being non-detectable. Bearing in mind the difficulty of determining the exact magnitude of potential effects of roads on sediment relationships, some of the potential effects of roads on water quality include increased suspended sediment concentrations and turbidity (Beschta 1978; Fredriksen 1970; King and Gonsior 1981; Rice et al. 1979) and increased deposition of fine sediment in spawning and rearing habitats (gravels and pools) (Eaglin and Hubert 1993). These relationships are far from straightforward, however, because in many forest stream systems, other factors such as large woody debris or bedform are the dominant controls on streambed texture (Buffington 1995).

3 This storm event was used as an example because an increase in peak flow of around 20% can increase the

volume of a 2 year flood to the equivalent of a 5 year event, which is considered to have significant effects on bed scour and salmonid egg mortality (WFPB 1997). 4 Bunte and MacDonald (NCASI 1999) provide a more detailed discussion of the variability of suspended sediment

and bedload in streams and the difficulty of detecting management effects with monitoring.24 In most cases, research in the Northwest has found that suspended sediment concentrations in streams increase significantly immediately after road construction. Increases reported following construction of roads in the 1960s and 1970s were as much as 250 times the expected undisturbed condition (Beschta 1978; Fredriksen 1970; King and Gonsior 1981; Rice et al. 1979). In one study, the increase was attributed to road-related mass failures, as suspended sediment concentrations in a nearby watershed with no mass failures did not show a significant increase in suspended sediment in the first year after road building (Beschta 1978). However, those same studies generally show that suspende d sediment concentrations diminish substantially within 1 to 2 years following construction, often returning to levels similar to those prior to construction. Furthermore, at least one study reported that most of the additional material was stored in small channels and was not immediatel y transported out of the watershed (King and Gonsior 1981), although transport of “stored” materials to downstream locations eventually occurs (NCASI 1999).

2.5.2 Bedload Sediments Bedload transport is even more episodic and variable than suspended sediment (NCASI 1999). Nonetheless, increased fine and coarse sediment supply, often due to landslides associated with roads, can cause changes in channel morphology such as widening, shallowing, or braiding (Lyons and Beschta 1983; Madej 1978). Bedload sediments from mass erosion usually cause considerable aggradation at the point of inflow. For example, Benda and Dunne found that debris flow deposits often formed fans that induced channel bends at the point of deposition. Over time, aggraded sediments are routed downstream as a function of sediment particle size, streamflow rate, and channel conditions. In many cases, the majority of sediment from mass erosion is not immediately transported fluvially, but is stored for considerable periods of time in lower order channels at the point of deposition and released in episodic events, resulting in higher order channel aggradation/degradation cycles of 100 to 1000 years (Benda and Dunne 1987). Sediment residence times and effects on channel morphology and aquatic habitat conditions also vary depending on the nature of the channel system and its hydrology (Benda and Dunne 1987; Duncan and Ward 1985). In some cases, deposition of fine or coarse sediment in streams has not been correlated with road density (Duncan and Ward 1985), new road construction (Fredriksen 1970), or even with specific road sediment input locations (Bilby 1985). However, in some cases, certain indices such as substrate embeddedne ss have been correlated with indicators like the density of stream crossing culverts in the watershed (Eaglin and Hubert 1993). It is possible to assess channel susceptibility to increased bedloa d sediments through channel inventories designed to evaluate effects of past sediment inflows and the hazards and risks of additional bedload sediments (Montgomery and Buffington 1993). 2.5.3 Effects of Roads on Streamflow Increases in peak flows, if large enough, can cause increases in scour and fill or bank erosion, leading to further increases in sediment transport (Roberts 1987; WFPB 1997). Roads potentially increase peak streamflows by replacing subsurface flow paths with surface flowpaths through capture of subsurface water in road cuts and by reducing the rate of infiltration into25 compacted surfaces, thereby generating excess surface flows. However, the role of logging roads in altering the magnitude and timing of peak flows remains poorly understood (Wemple, Jones, and Grant 1996). It has been hypothesized that increases in peak flows from roads may be due to increases in “drainage density” stemming from connectivity betw een the road system and the stream network at channel crossings and through gullies below relief drains (Montgomery 1994; Wemple, Jones, and Grant 1996; Jones et al. 2000). Although various studies have suggested increases in “drainage density” of 23 to 60% due to roads (Bowling and Lettenmaier 1997; Montgomery 1994; Wemple, Jones, and Grant 1996), road mileage that drains to streams is not the same as an increase in the length of streams within the watershed (Jones et al. 2000). Surface water in streams develops as subsurface flow through th e soil and geologic man tle accumulating to the point of saturation causing channelized surface flow. Roads also intercept subsurface flow, but interception may be partial, and there is a compensating effect in that runoff from intercepted subsurface flow is not supplied to the slope below the road, so storm runoff from the portion of the watershed below the road is reduced (Bowling and Lettenmaier 1997). Furthermore, if drainage density did actually increase because of road connectivity, relationships developed for natural drainages linking flood peaks and low flows to drainage density should be suitable for predicting the flow changes that occur from increased “drainage density” from road construction. However, studies of road construction effects on experimental watersheds show no such effects (Harr et al. 1975; Rothacher 1973). Jones et al. (2000) suggested that indices based on the number of road-stream crossings, particularly at mid-slope locations, may be more reflective of potential road effects on watershed processes than road density alone. Arguments are made that runoff from intercepted subsurface flow occurs rapidly as concentrated overland flow, and therefore tends to increase peak flows (Jones and Grant 1996). This effect may or may not occur, because subsurface flow often occurs in macropores, where flow velocities can exceed that of overland flow. In such situations, intercepting overland flow will reduce peak flows (Bowling and Lettenmaier 1997). In fact, Cheng et al. (1975) reported that compaction associated with logging in a coas tal British Columbia watershed reduced peak flow magnitude and time to peak because large subsurface channels which normally transported stormwater were crushed (although no surface flow resulted), forcing stormflow through the soil matrix at reduced velocity. Potential effects of roads on peak flows depend on the specific characteristics of the road and the watershed in question. For example, according to a recent Forest Service document (Gucinski et al. 2000): The effects of roads on peak streamflow depend strongly on the size of the watershed. For example, capture and re-routing of water can dewater one stream while causing major channel adjustments in the stream receiving the additional water. In large watersheds, roads constitute a small proportion of the land surface and have relatively insignificant effects on peak flow. Road effects on peak flows also depend on road location within the watershed. Jones and Grant (1996) hypothesized that road construction increases the peak and shifts the hydrograph forward in time compared to non-roaded watersheds. Assuming this is the case for a sub-basin within a26 larger watershed, Bowling and Lettenmaier (1997) showed that peak flows are increased at the larger watershed scale only if the road construction takes place above the centroid (i.e., in the upper part) of the larger watershed. Road construction near or below the centroid of the larger basin desynchronizes the runoff hydrograph at the downstream location, leading to decreased peak flows. Such de-synchronization effects may be responsible for the erratic results from field studies of the effects of road construction on peak flows in experimental watersheds, some of which show peak flows increasing, some decreasing, and others showing no statistical change. In some of the earliest work on road effects on peak flows, Rothacher (1970, 1973) did not detect any significant increases in mean peak flows or annual water yields due to roads that occupied 8% of a 250 acre western Oregon watershed. In the Oregon Coast Range, Harr et al. (1975) reported that roads increased mean annual peak flow by 19% in a watershed with 12% of area in roads, but that watersheds with 3 to 5% of area in roads showed no significant increases in mean annual peak flows. Ziemer (1981) and Wright et al. (1990) found no significant increases in peak flows for a 1047 acre watershed in coastal northern California with 5% of the area in roads and 8% in tractor skid trails. In seven small forested headwater basins in northern Idaho (ranging in size from 69 to 365 acres) with 1.8 to 4.3% of area in roads, five watersheds experienced no significant increases in mean annual peak flows, peak flows decreased in one of the seven basins, and flow during spring snowmelt increased 30% in one watershed with a mid-slope road occupying 3.9% of the watershed area (King and Tennyson 1984). In the H. J. Andrews Forest of western Oregon, Jones and Grant (1996) concluded that 6% of the area occupied by roads in a small (250 acre) watershed caused a (non-significant) 20% increase in mean annual peak flows. They also argued that roads and clearcutting in large watersheds (15,000 to 150,000 acre) have caused increases in peak flows in larger basins. They attributed much of the effect to altered flow paths caused by roads. However, using a different statistical methodology with the same data set as Jones and Grant (1996), Thomas and Megahan (1998) found significant increases in peak flows in the small watershed that was roaded and patch-cut, but only in the first 10 year period following harvest, which implied that the effect was due to harvest, with little effect from roads, as road effects should be more persistent. Thomas and Megahan found increases in peak flows of 15 to 40%, but percentage increases in peak flows decreased with increasing return interval, with no increases detectable for flows greater than the 2 year flow, which is generally considered the flow level where effects on stream channels begin to occur. In another re-analysis of the data set used by Jones and Grant (1996), Beschta et al. (2000) essentially agreed with the conclusions of Thomas and Megahan (1998), but concluded that “peak flow increases for 0.4 to 5 year return interval events have occurred on small watersheds as a result of clearcut silviculture and the accompanying effects of roads and broadcast burning as practiced in the mid-1960s.” They concluded that peak flow increases in the small watershed were not detectable for flows of 5 year return interval or greater, and they further concluded that the analysis did not support Jones and Grant’s conclusion that peak flows were increased in larger basins. These watershed studies have demonstrated numerous potential effects of roads. However, it is not practical, or even possible, to evaluate all the effects of road construction using experimental watershed studies, given the infinite combinations of various site-specific factors and different27 weather and storm patterns, as well as all of the road design and road location factors that might affect peak flows. To address this problem, hydrologists develop process-based models that allow both an examination of a wide variety of circumstances and a determination of the effects of individual factors. The Distributed Hydrologic Soil Vegetation Model (DHSVM) is a process-based, hydrologic model designed to evaluate the effects of ro ad construction and timber harvest on streamflow (Bowling and Lettenmaier 1997; Wigmosta et al. 1994). Applications of the model to evaluate effects of forest roads on peak flows (isolated from the effects of forest cutting) in specific forested watersheds show mixed results, with most studies showing increases in peak flows:

In Hard and Ware Creeks in western Washington (Bowling and Lettenmaier 1997), modeling showed that road densities of 6 to 8 mi/mi 2 , with 17 to 20% of the road mileage connected to the stream system, increased mean annual peak flows by 11%; flows substantially smaller than the mean annual peak flow were increased 13 to 17%; 5 year flows increased 9 to 10%, and 10 year flows increased 8 to 10%.

In the Deschutes River basin in western Washington (La Marche and Lettenmaier 1998), modeling showed that road densities of 5 to 8 mi/mi 2 increased mean annual peak flows by 2.4 to 10.2%; flows smaller than the mean annual peak flow were increased 1.8 to 10%; and 10 year flows increased 2.5 to 12.2%. For purposes of comparison, it should be noted that individual annual peak flows in the Deschutes River basin have varied by approximately a factor of four over a 50 year period of record. These modeling studies provide an estimate of the potential for road effects on peak flows. However, the question remains whether the models simulate the entire effects of roads. Whether such (modeled) peak flow increases are actually measurable in watersheds, and whether observable effects on stream channel characteris tics and aquatic habitat quality occur remains uncertain. There are virtually no studies that have documented channel effects caused by increased peak flows attributable to roads. Hydrologic effects of roads on channel morphology are difficult to predict with models and difficult to isolate and measure in watersheds. As an illustration, peak flow increases due to roads are generally detectable only for flows less than the 2 to 5 year return interval (Beschta et al. 2000; Thomas and Megahan 1998), while the most significant channel-forming events are considered to be on the order of the 2 to 10 year return interval (“bankfull flow”) events or larger (Beschta et al. 2000). This difficulty is compounded by the fact that other factors also influence channel scour, and therefore affect channel morphology, often to a greater degree than peak flows. For example:

Sediment size – Scour and fill depths may be more a function of sediment size distribution than flood magnitude (deVries 1998).

Disturbance history – Channels that received coarse sediment from upstream landslides had greater scour (Tripp and Poulin 1986).

Flood duration – Some studies have found that flood duration can be as important as flood magnitude (Costa and O’Connor 1995).28Stream characteristics – The size, bedform, slope, and roughness (e.g., rocks, large wood) of the channel influence scour (Bilby and Ward 1989; Buffington 1995; Keller and Swanson 1979; Megahan 1982). The effects of these factors, as well as peak flows, on channel morphology will no doubt be the subject of future research. Nonetheless, the potential effects of roads on peak flows do in part depend on the mileage of road that drains direct ly to streams at crossings and through gullies. Managers should recognize that this mileage can nearly always be controlled through road drainage design, including insloping versus outsloping and installation of drainage structures at critical locations. 2.6 Effects on Stream Habitat and Fish Populations Understanding the effects of roads on erosion, runoff, and delivery processes and the effects of these inputs on stream channels and water column conditions must be followed by an understanding of the effects on fish habitat and populations – the last technical steps in Critical Pathway Analysis. With the technical understanding, albeit imperfect, management systems and practices designed to limit inputs and effects to acceptable levels are then put in place. Management practices and systems are discussed in Section 2.1 and Appendix B. Changes in hydrology or sediment inputs to streams can affect the physical environment for fish at various stages of their life history, as well as human uses:

Increases in turbidity can affect the feeding and territorial behavior of fish (Berg and Northcote 1985; Reiser and Bjornn 1979).

Extremely high turbidities can delay upstream migration of salmonids (Bjornn and Reiser 1991).

Fines in gravels can reduce salmonid embryo survival and/or emergence (Bjornn and Reiser 1991; Cederholm and Salo 1979; Koski 1972; Weaver and Fraley 1990).

Fines in gravels can reduce winter rearing habitat for fish by filling pools and reducing available cover (Bjornn et al. 1977; Reiser and Bjornn 1979).

Fines in gravels can cause a reduction in the number of benthic invertebrates available as food for adult salmonids (Bjornn et al. 1977; Cederholm and Salo 1979).

Increases in peak flows can affect the incuba tion environment for fish where small increases in scour depths might significantly affect many salmon redds (Montgomery et al. 1996).

Although road construction and timber harvest are not often major factors affecting turbidity levels of municipal water supplies, in some cases land use factors can contribute to landslides during major storms, which can increase short- term turbidity levels (Grizzel and Beschta 1993).

Floods can affect human safety and damage structures or property (WFPB 1997). Generally, although these effects have been demonstrated, translating them to populations has not been easy to do. Various measures and approaches for translating levels of input of water29 and sediment to streams to effects on instream habitat conditions and fish populations have been explored, and this is discussed in Section 2.7. 2.7 Targets and Indices

It is often difficult to determine the acceptable level of impact on stream flows or sediment loads, or conversely, when impacts to channels, fish habitat, and ultimately to fish populations are unacceptable. Ideally, and in concert with the concept and final steps in pathway analysis, targets and indices for these parameters would be determined by use of some ecological metric that has been established by conclusive experimental research that links level of road input to degree of ecologic response. Then the level of acceptable impact would cease to be a question to be answered with science; it would be determined through so cial and political processes, suggesting that there may be no one correct and true level of acceptability. Notwithstanding the difficulty of determining “how much is too much,” approaches relying on somewhat imperfect science have been emerging that seek to establish targets, indices, and management systems that limit impacts to levels that are curre ntly judged to be acceptable. Perhaps the ultimate goal would be to establish targets at the level of input where biologically detectable acute or chronic effects upon organisms (e.g., fish) do not occur. State water quality temperature standards provide an example of this approach, albeit levels set to date remain controversial and are far from settled as pure matters of science. Meaningful targets for sediment are even more elusive. However, the effects of sediment on water quality, the physical habitat that organisms depend upon, and ultimately upon the population itself, is highly variable, and poorly understood quantitatively. Adding to this complexity of biological response are additional and intermixed effe cts, both on-site and off, such as those of fishing or exotic predators, and all manner of activities that affect anadromous and migratory populations downstream from the area of concern. As a result, most systems for targeting levels of sediment or flow input avoid linkages to biological response and limit themselves to relationships of input to physical instream and habitat response. 2.7.1 Reference Streams One approach that has been implemented to various degrees relies upon “reference streams.” With the reference stream system, a population of “natural” streams thought to represent a particular ecosystem is measured for physic al and/or biological characteristics. Various statistical measures of the data are then used to indicate the reference condition for that ecosystem stream type. For sediment, parameters such as percent surface fines, cobble embeddedness, or percent pool filling have been used. Metrics used to represent these parameters include the mean, variance, range of the data, and various other statistical measures. However, even for a set of streams determined to be within a particular stream type/ecosystem, variability of sediment metrics is often extreme, even within undisturbed systems. As a result, pure application of the reference system could judge a stream with a known and perhaps even extreme past and continuing history of road sediment input to be acceptable. This situation has led to various means of modifying pure application of the system. A modified reference stream appro ach that has been considered restricts the acceptable zone to only a portion of the full range exhibited by the natural stream population (USEPA 1999). This30 system has generally been rejected because, by definition, even some natural streams are found to be out of compliance with the standard. A more promising system reviews the status of an entire population of streams to see if the distribution of parameter values is different from the natural distribution. If it is, excess sediment input is indicated. The question remains: what is (or has been) the source of the sediment? Stand alone application of the reference stream approach does not answer this question. Application of the critical pathway steps to a reference stream “goal” begins to build the linkages necessary for achieving a sound cause and effect understanding that allows identification of appropriate management systems and practices. One encouraging means of building on the reference stream approach is to couple stream indices with measures that index road system inputs (in this example, sediment) to the stream. In one manner or another, this is the system being implemented by various states and companies. In these systems, instream measures of stream hea lth (physical and/or biological) and evaluations of road sediment input are coupled in a management system that establishes levels or indices of sediment input that in turn indicate whether the input is acceptable or not. The target sediment input level must be decreased until the stream condition, as indicated by indices such as percent surface fines, channel stability, channel geomorphic type, or s imilar measures, is judged to be acceptable. This approach can be based on re ference streams or on less rigorously quantitative approaches such as watershed analysis, which builds “the watershed story” largely from evidence of process and response observable within the watershed. Either way, the approach provides integrated watershed and road management systems that allow modification of goals, indices, and management practices as local and global knowledge bases increase. Such systems are described in Appendix B. 2.7.2 Sediment and Runoff Indices In some cases, sediment and runoff targets used to set limits on acceptable change are set at the input level. For sediment in Washington, the goal is to locate areas in the watershed likely to experience significant changes in sediment that result in chronic changes in turbidity or deposition of fines in streambeds affecting aquatic life. Washington requires application of prescriptive management practices to limit sed iment delivery in watersheds where analysis shows that fine sediment delivery has increased to 50% above natural background rates oferosion. This is based on evidence that sediment yields increased by 50% or more of the longterm average are detectable with water sampling procedures. Similarly, Washington suggests that changes in peak flows of up to 10% are diffic ult to detect or reliably predict. They also suggest that the 5 year peak flow or larger is the important channel-forming event in mountain channels, and that an increase of approximately 20% in the 2 year peak flow is needed to produce the 5 year flow. Accordingly, Washington uses these 10% and 20% figures to index potentially harmful increases in peak flows, and requires adjustment of management practices in watersheds where analysis indicates that such increases may be occurring (WFPB 1997). Similarly, Idaho has set limits that are dependent on instream conditions, and that are designed to protect beneficial uses based on sediment indices and level of watershed harvest reflective ofpotential peak flow effects. Using this system, mass wasting, road surface erosion, and loggingrelated sources of accelerated erosion are indexed, and channel conditions related to sediment are evaluated and indexed. If both indices considered together indicate that excessive production of sediment has produced adverse instream conditions, sediment sources in the watershed must be31 addressed to reduce erosion and delivery. For peak flows, Idaho limits harvest acreage based on an index of watershed hydrolog ic condition and stream stability, with acreage more restricted where streams are less stable and subject to adverse effects on peak flows (IDL 2000b) (see Figure 5).

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

1

20 30 40 50 60 70 80 Channel Stability Index (CSI)Canopy Removal Index (CRI)

Low Moderate High

Figure 5. Idaho Hydrologic Risk Rating

2.7.3 Road Density Indices In contrast to approaches that set targets based on cause/effect critical pathway analysis of levels of input to instream effects, some approaches attempt to regulate road construction effects with indirect indices such as road density. While a number of studies have shown correlation of road density to deteriorated instream conditions and fish populations (Gucinski et al. 2000), such approaches do not provide efficient means of managing potential effects on downstream beneficial uses, because the lack of a linkage between input and effect does not allow efficient allocation of finite road management resources to th e specific problems (causes) that must be addressed to prevent and solve impacts (effects). The temp tation is to regulate watershed road density based on correlation to instream conditions that may be due to historic effects or effects not related to current road sediment and runoff conditions. While indirect effects on fish populations may indeed be correlated with presence and even density of roads, these impacts are best controlled through devices such as control of access (road closure and use regulation) or fishing regulations, and that these effects are not related to watershed processes nor to the direct effects of roads addressed in this paper. Because quasi-regulatory road density based index approaches have surfaced, particularly associated with the Federal Endangered Species Act (NMFS 1996; USDAFS 1993) and Clean Water Act Total Maximum Daily Load (TMDL)32 processes, it is important to elaborate on the weaknesses of such systems for addressing direct road impacts. The scientific literature firmly establishes that forest road s can add significant quantities of sediment to streams, and in some circumstances have been found to affect streamflow relationships (Beschta et al. 2000; Bowling and Lettenmaier 1997; Thomas and Megahan 1998). Roads can also cause a number of additional dir ect impacts to aquatic habitats. Prior to development of current forest practices rules and modern operating restrictions, these impacts included construction of roads within and adjacent to channels, straightening of channels, permanent removal of shade, and loss of channel-adjacent large woody debris producing vegetation and growing areas. Most of these impacts are associated with roads that were poorly located, poorly constructed, or improperly maintained in riparian areas or on steep and unstable slopes (Brown and Krygier 1971; Fredriksen 1970; Furniss et al. 1991; McGreer et al. 1997; Megahan and Kidd 1972; Packer 1967; Rice et al. 1979; Swift 1986; Trimble and Sartz 1957). Proper interpretation of road effects in speci fic watersheds requires consideration of these location and road management factors. Working at very broad scales, where specific factors could not be analyzed, the Interior Columbia Basin Ecosystem Management Project (ICBEMP) Assessment of Ecosystem Components in the Interior Columbia Basin (Quigley and Arbelbide 1997) recently stated in the executive summary that “increasing road densities (combined with the activities associated with roads) and their attendant effects are associated with declines in the status of four anadromous salmonid species.” They note that activities associated with roads may affect fish populations, including fishing, recreation, timber harvest, livestock grazing, and agriculture, and that roads provide avenues for stocking of non-native fishes. The assessment also stated that, “Unfortunately, we do not have adequate broad-scale information on many of these attendant effects to accurately identify their component contributions. Thus, we are forced to use roads as a catch-all indicator of human disturbance.” At the broad scales examined by the ICBEMP, it is not surprising that a positive correlation was found between road density, fish, and habitat quality. Indeed, if impact from all road miles within any given basin are assumed to be equal, irrespective of road location and management practices, and if all other factors responsible for effects upon streams and fish within basins are ignored (the simplifying assumptions relied upon by the ICBEMP assessment), then road density, stream habitat, and fish declines may be correlated to some degree. However, widespread experience backed by a vast literatu re base allows us to avoid such simplifying assumptions when dealing with management of specific watersheds and allows us to establish cause and effect relationships between roads, stream habitat features, and fish populations. Regarding sediment, which is the predominant pot ential adverse effect of roads on streams (as long as roads are no longer located within channels), Figure 6 demonstrates that sediment delivery is not correlated with road density. 5 Figure 6 is based on field inventories and modeling of road erosion and sediment delivery using Washington watershed assessment procedures (WFPB 1997) applied to watersheds located throughout the coastal and inland northwest.

5 Although Figure 6 does not indicate the different geologic types encountered in the various watersheds,

categorizing the data by geologic ty pe reveals no discernible trends.33 0 10 20 30 40 50 60 70 80

012345678 Road density (mi/sq.mi.)Sediment delivery (tons/sq.mi.)

Figure 6. Road Sediment Delivery vs. Road Density
The explanation for this lack of correlation (and therefore lack of a cause-effect relationship) is, as discussed earlier, that some but not all roads deliver sediment to streams, and even those roads that do deliver sediment deliver it at rates that vary by orders of magnitude. Further, where land managers recognize higher hazards for road erosion they can modify road design and maintenance practices to minimize impacts (Bourgeois 1978). In many watersheds, specific road segments are responsible for a disproportionately high share of total road sediment delivery, as illustrated in Figure 7. These figures help emphasize that if the major stream impacts in a watershed are associated with se diment discharged from roads, the means of control is to identify and treat the specific roads that contribute the sediment, not merely to reduce road density. The realization that not all roads are equal has lately received increased recognition. In concluding a broad discussion of direct, indire ct, and landscape-scale effects, the USDA Forest Service (Gucinski et al. 2000) states:

Measures of the cumulative effects of roads more closely related to mechanism (for example, the length of roads connected by di rect surface-flow paths to streams or the miles of potential habita t blocked by culverts) would be more likely to produce stronger relations between roads and aquatic habitat elements than would road density.34 0% 20% 40% 60% 80% 100%

0% 20% 40% 60% 80% 100% % cumulative road mileage% cumulative road sediment

Upper West Branch Upper East Branch Middle Branch Figure 7. LeClerc Creek Watershed Road Sediment Examples

2.8 Habitat/Population Feedback to Management System When considering potential effects of roads on habitat and populations, the species of concern are most often fish, typically salmonids. Howeve r, managers are increa singly being required to address all aquatic species, including amphibians and macroinvertebrates (e.g., tailed frogs, salamanders). In any case, a knowledge of the cause and effect linkages between roads and beneficial uses, as discussed in Sections 2.2 through 2.7, provides feedback to help determine how road related environmental effects can be systematically mana ged within acceptable levels. The framework of this feedback is the basis of the adaptive management approach. When habitat or population objectives are not achieved, adjustments are made in the management practices employed. The management system is the vehicle used to identify where and how those adjustments are to be made. Management systems may be based on state forest practice rules or BMPs, watershed or landscape analysis procedures, special issue management methods, or some combination of these. Examples of various management systems are described in Appendix B.

3.0 RESEARCH NEEDS A number of subjects where uncertainty continues to exist regarding the relationship of roads to stream systems and effects on aquatic ecosystems are discussed herein. Although not a detailed discussion of these uncertainties and research approaches that might be used to address them, the most important subjects that require additional research include:

Improve understanding of relationships between input levels, both sediment and water, and channel responses.35Improve understanding of channel response effects on aquatic habitat and population response.

Develop methods to identify areas with high hazards of excessive sediment or water inputs to streams.

Monitor the effectiveness of road practices at the project and watershed scale to show that sediment is appropriately reduced.

Develop and validate targets and indices that relate input levels to channel, habitat, and population responses.

Validate and improve, where necessary, road sediment erosion and sediment delivery models.

Validate and improve, where necessary, road water delivery models.

Evaluate the role of culvert water discharge in gully formation and design guidance for its control.

Quantify how and what types of culverts cause fish passage problems.

4.0 CONCLUSIONS The impacts and values of forest roads have been the subject of recent debate. Forest roads historically have produced substantial adverse effects on streams, and depending on how they are managed, may continue to adversely impact streams today. While there is no doubt that roads can impact the aquatic environment, roads are also necessary for management of forest lands. Although roads are essential to land management for forest products, fire control, and other uses such as recreation, there remain legitimate concerns about where roads should be located and how many roads are necessary. Roads must be located to serve their intended transportation system objectives while at the same time meeting environmental constraints and requirements. These dual objectives provide a classic case where neither objective can be completely optimized, and a satisfactory solution is sought wherein both economic and environmental goals can be adequately met. Harvest methods, anticipated traffic, operating speeds, and safety requirements must be considered. All of these influence road width and alignment, which affect the area of disturbance and subsequent environmental consequences. Complex terrain, land ownership patterns, and/or environmentally unacceptable locations often dictate road spacing, which in turn often requires road density to increase beyond an economic optimum. Road building, upgrading, and maintenance are basic to commercial forestry operations and require a significant part of company operating budgets. Because of their high value and potential environmental consequences, road assets are constantly managed. Management includes transportation system planning, route reconnaissance and location, road design, road construction, road maintenance, upgrading, and road closure and obliteration. Most of the roads needed today for management of private lands have already been built, but many of these roads were not located, designed, or built to current standards necessary to meet environmental goals. Assessment of road system effects must consider the proportion of old roads to new roads that incorporate improved engineering design (Gucinski et al. 2000).36 Although substantially improved road management practices have evolved during recent years, managers must continue to address four major potential impacts of roads on aquatic ecosystems. These potential effects include 1) increased peak flows that, if large enough, may adversely affect channel morphology and dependent biological systems; 2) erosion and delivery of sediment to streams through surface erosion processes that can lead to filling of interstitial spaces in streambed gravels and/or by increasing turbidity levels, and through mass erosion (landslides) where large quantities of coarse sediment delivery can contri bute to channel scour, deposition, avulsion, and other major affects on channel morphology; 3) channel encroachment, a legacy of old roads that must be considered in road maintenance, upgrading, and closure plans; and 4) fish passage at road-stream crossings. Critical pathway assessment based approaches, like those developed by Washington, Oregon, and Idaho, are effective management systems that establish the cause-effect linkages between forest roads and aquatic systems. Applied to ro ads, critical pathway analysis traces how roads influence watershed processes (runoff and erosion) in the vicinity of the road, and determine and quantify how water and sediment are delivered from roads to streams and are routed through the stream channel system. Channel responses are then interpreted in terms of possible effects on stream habitat and fish populations. This report contrasts critical pathway analysis with less effective approaches that attempt to regulate road construction effects with coarse indirect indices, such as road density, which do not link cause and effect and therefore do not efficiently allocate finite road management resources to the specific problems that must be addressed to prevent adverse effects. Roads increase erosion because of effects on hydrologic processes as well as changes in site factors that influence erosion rates. Although effects vary greatly depending on specific site conditions, both surface and mass erosion rates and delivery of sediment to streams often increase with road construction in mountainous areas. Sediment delivery from roads due to surface erosion is a function of the volume of water discharged from the road, the volume of sediment carried by that water, and character istics of the pathway that the water/sediment solution travels. Sediment delivery due to mass wasting is a function of the characteristics of slopes where roads may be located, as well as road designs and construction. By understanding these processes as they apply to the specific circumstances of watersheds, as established by watershed assessment and road inventory procedures, managers can effectively reduce and control impacts to levels estab lished as acceptable by current standards. Uncertainty exists regarding these standards and the targets and indices that reflect them, and future research will be needed to refine them through time. Similarly, although potential effects of roads on peak flows and channel morphology are probably limited to effects within small watersheds, and the magnitude of such effects remains uncertain, they can be managed through regulation of the amount of road “connected” to stream systems. Applying appropriate road practices in forest watersheds to reduce negative water quality impacts requires two elements: a set of management practices for roads which can effectively reduce water quality impacts; and a management system which ensures that the right practices are applied in the right places. The manageme nt system is used to select and implement practices chosen from the set of management practice options. Both current management activities and watershed ha zards, as well as hazards and imp acts that occur due to historic activities, must be addressed.37 Effective management systems for roads require several steps. These include inventory of road and stream conditions, identification of road sections requiring practices to bring them into acceptable condition, identification of effective practices and costs, development of priorities and a schedule of work, appropriate timeframes for implementation and completion of necessary tasks, implementation monitoring, inspecti on to determine performance of implemented practices, and personnel training. Building on state forest practice rule BMP-based systems, western states including Oregon, Washington, and Idaho have developed watershed analysis systems that address watershed conditions on a site-specific basis. Habitat conservation plans and other special issue management systems, including those developed by a number of forest products companies, have also been developed to meet current environmental objectives and standards.

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. Ukiah, CA: Mendocino County Resource Conservation District. Wemple, B.C. 1999. Investigations of runoff production and sedimentation on forest roads. Ph.D. dissertation. Corvallis, OR: Oregon State University. Wemple, B.C., Jones, J.A., and Grant, G.E. 1996. Channel network extension by logging roads in two basins, western Cascades, Oregon. Water Resources Bulletin 32(6): 1195-1207. Wigmosta, M.S., Vail, L.W., and Lettenmaier, D.P. 1994. A distributed hydrology-vegetation model for complex terrain. Water Resources Research 30(6): 1665-1679. Wischmeier, W.H., and Smith, D.D. 1965. Predicting rainfall-erosion losses from cropland east of the Rocky Mountains . Agriculture Handbook No. 282. United States Department of Agriculture. Wright, K.A., Sendek, K.H., Rice, R.M., and Thomas, R.B. 1990. Logging effects on streamflow: Storm runoff at Caspar Creek in northwestern California. Water Resources Research 26(7): 1657-1667. Ziemer, R.R. 1981. Storm flow response to road building and partial cutting in small streams of northern California. Water Resources Research 17(4): 907-917.A1 APPENDIX A

MICA CREEK EXAMPLE OF HISTORIC LOGGING METHODS AND IMPACTS
The transformation from rail and water-based forms of logging and transport to modern era logging methods and the road location and design that facilitate them are illustrated by the history of activity in the Mica Creek watershed, a 38 mi 2 watershed tributary to the St. Joe River in northern Idaho. This watershed was extensively logged in the 1920s and early 1930s. The transportation and logging system patterns and methods used are evident from 1933 stereo aerial photography. Evidence of these early activities also remains in the watershed today, and includes old railroad grades, trestles, trenches from ground skidding, flumes, splash dams, log chutes, and log corduroyed skid trails. Timber in the lower portions of slopes near streams was skidded downslope to the valley bottoms. The typical pattern was to skid logs by dragging them with horses to timber chutes that were constructed in the first and second order draws that led to the valley bottoms of larger streams. Some of these larger streams were covered with log corduroy roads where logs were skidded with horses and wheeled carriages. At that point the logs were channeled into wooden flumes located in and adjacent to the main th ird and fourth order tributaries of the watershed. The flumes joined downstream and extended for several miles down the mainstem of Mica Creek until they reached a narrow valley constricti on where a splash dam was constructed that periodically flushed logs for several more miles to the St. Joe River. It is not hard to imagine that downhill skidding to instream and stream-adjacent transportation corridors without benefit of erosion control caused tremendous impacts to the stream network of Mica Creek. These impacts included stream dewatering, direct physical disturbance of stream morphology, destruction of riparian vegetation, solar exposure, removal of instream large wood, and introduction of sediment in quantities that exceeded natural rates of watershed erosion by an estimated two to three orders of magn itude for a period of several years. Conversion of railroad grades to truck roads in the 1940s and 1950s resulted in the location of mainline roads that accessed major watersheds ad jacent to rivers and streams. Because the mainlines were located in the valley bottoms, the remainder of the road transportation system was constructed to lead downslope to it, and often these roads were also constructed on old railroad grades or original locations that followe d tributary stream courses. The result is that extensive road systems have developed that lie in stream-adjacent locations. A second, and often equally important, effect is that after leaving valley bottoms, roads could be built on steep slopes. These early mid-slope roads were often constructed with bulldozers and excavated materials were sidecast onto steep and unstable slopes, resulting in numerous landslides in many watersheds (Sidle 1985). Construction machinery and techniques and road location requirements that consider landslide hazards have eliminated many of these problems during the past 30 years, but a legacy of old road problems remains. In many cases, these legacy problems can be systematically eliminated, or at least reduced in severity, and formal regulatory and non-regulatory programs to reduce these legacy effects have been implemented in recent years throughout much of the western forest lands. Examples of such programs include road maintenance and abandonmentA2 requirements of Washington’s “Forest and Fish Agreement,” forest practices act rules (WFPB 2000), Oregon State’s Plan for Salmon and Watersheds (ODF 2000), and Plum Creek Timber Company’s Native Fish Habitat Conservation Plan (Plum Creek Timber Company 2000). Seventy to eighty years have passed since the early logging in Mica Creek. The watershed is once again densely forested, and streams have recovered to a remarkable degree. For example, a striking array of sediment-intolerant macroinvertebrates currently populates Mica Creek. To facilitate logging planned for the headwater areas of the watershed in 2001, new forest roads have been constructed. The new road system allows virtually all areas of the headwaters to be logged by ground-based systems on moderate to gentle slopes and ridgetops above the roads, and by aerial cable systems below the roads. Of particular relevance to the subject of this paper, this road system was located with great care to minimize stream crossings or other locations where sediment delivery to streams is likely. The effect of roads and logging in the Mica Creek watershed is being monitored in a research setting by Potlatch Corporation and NCASI (McGreer et al. 1995). The nature of the road locations and constructi on standards, as well as preliminary results following road construction, lead to an estimate that sediment delivery to streams will be no more than 10% to 50% above natural watershed rates of erosion, decreasing to even lower rates within one to two years following logging. In fact, a detailed analysis of sediment sampling from Mica Creek showed no increase in suspended sediment in the first year following road construction (Mosier 1999). The contrast between historic and modern methods is huge, and while details vary from one watershed to the next, the Mica Creek history is representative of similar watershed histories throughout the west.

References McGreer, D.J., Cundy, T.W., and Gravelle, J.A. 1995. Mica Creek cumulative watershed effects study. In: Watershed Management Planning for the 21st Century . August 14-16, 1995, San Antonio, TX. Watershed Management Committee of the Water Resources Engineering Division/ASCE. p. 300-309. Mosier, D.D. 1999. Influence of road construction on stream water quality in the Mica Creek watershed, Shoshone County, Idaho . Master’s thesis. Moscow, ID: University of Idaho, Geological Engineering Department. Oregon Department of Forestry (ODF). 2000. Forest road management guidebook: Maintenance and repairs to protect fish habitat and water quality . Salem, OR: Oregon Department of Forestry. 32 p. Plum Creek Timber Company. 2000. Native Fish Habitat Conservation Plan . Seattle, WA: Plum Creek Timber Company. Sidle, R.C. 1985. Factors influencing the stability of slopes. In: Proceedings of a Workshop on Slope Stability: Problems and Solutions in Forest Management . General Technical Report PNW-180. United States Department of Agriculture Forest Service, Pacific Northwest Forest and Range Experiment Station. p. 17-25.A3 Washington Forest Practices Board (WFPB). 2000. Forest Practices Act Board Manual

. Olympia, WA: Washington Department of Natural Resources. 212 p.B1 APPENDIX B

MANAGEMENT SYSTEMS AND EFFECTIVENESS

B.1 State BMP Management Systems Nearly all state forest practices BMP programs, including state forest practices acts, were initially developed in response to the requirements of Section 208 of the 1972 Federal Clean Water Act. Accordingly, each state’s BMPs share the basic objective and requirement of maintaining the beneficial uses of the wate r and meeting the state’s water quality standards. However, there are substantial differences between these BMPs and the state forest practice management systems designed to implement these rules. Oregon and Idaho have forest practice notification programs that are designed to alert state agencies to proposed operations. Notification allows for pre-harvest inspections where there are priority risks and where special protection may be needed. In Oregon, where there are special risks associated with activities in areas with a high risk of landslide or ne ar fish-bearing streams and wetlands, written plans are required. The Oregon and Idaho forest practice rules also allow for special protection rules in wate rsheds that are water quality limited. Washington uses a permit program, and there are several levels of review based on the risk category of the management activity proposed. The permit process is streamlined for activities where a watershed analysis has been conducted and approved by the Washington Department of Natural Resources (also see Section B.3), wherein management practices for the watershed have been developed cooperatively between scientists and managers. In California, comprehensive timber harvest plans are subject to an exhaustive review process by state agencies and the public. Only licensed professional foresters who have sufficient education and professional training and have passed an exam can submit timber harvest plans. Like Washington, streamlined approval can occur for operations covered by Sustained Yield Plans. These plans cover the sustainability of timber and public resources over large management areas. Special rule packages can be developed for individual counties or watersheds with endangered species or other risks. As discussed in Section B.5.1, the effectiveness and levels of compliance with BMPs have been formally evaluated by some states. B.2 Company Based Management Systems There is a range of management systems that companies or non-industrial private landowners may use to manage roads. At the base level is compliance with state forest practice rules and BMPs. These are considered the minimum standards needed to protect public resources. Repeated assessments have shown that complia nce with state BMPs and forest practice rules prevents major water quality impacts under most circumstances (Ethridge and Heffernan 2000). Compliance with all state BMPs is a commitment of all industrial timber companies who are members of the American Fo rest and Paper Association a nd who have committed to the Sustainable Forestry Initiative (SFI) (AF&PA 2000). One of the objectives of SFI is to “protectB2 the water quality in streams, lakes, and other waterbodies.” A key performance measure is “program participants will meet or exceed all established Best Management Practices (BMPs) approved by EPA, all applicable state water quality laws and regu lations, and the requirements of the Clean Water Act for forestland.” However, state BMPs can be inefficient, because they are designed to protect resources under the general circumstances encountered in the area regulated. The result is that state BMPs over-protect in some cases (wasting resources that could be applied to higher priorities) and under-protect in others (allowing undesired impacts). For this reason, some states have customized BMPs to regions within the state. States with diverse geographies and complex terrain, such as Washington, Oregon, and Idaho, have promoted various forms of watershed assessment to tailor BMPs more closely to the wa tershed and site conditi ons (see Section B.3). Most timber companies have much more complex management systems than mere compliance with state BMPs. An example of the many levels of management systems is Plum Creek Timber Company’s Habitat Conservation Plan for Native Fish (Plum Creek Timber Company 2000). In addition to a commitment to meeting state regu lations, Plum Creek developed an internal conservation plan, which goes well beyond state BMPs in order to systematically address special management issues – in this case, issues that ar ise due to the presence of threatened, endangered, or otherwise sensitive fish species. B.2.1 Plum Creek Timber Company’s Native Fish HCP Plum Creek Timber Company (PCTC) developed a Habitat Conservation Plan (HCP) for 17 species of native fish on 1.6 million acres of company ownership, most of which is in Montana. The plan was approved by both US Fish and Wild life Service and National Marine Fisheries Service as meeting the requirements of the Federal Endangered Species Act and will be in effect for 30 years. The HCP includes 56 commitments on the part of PCTC, covering all facets of their forest management system. A summary of these levels of commitment is provided in Appendix 1 of the Plum Creek HCP summary (Plum Creek Timber Company 2000). With regard to roads, the HCP requires as a base prescription that the company comply with all forestry BMPs. In Montana, BMPs are currently managed as a non-regulatory program. Because Montana’s forestry BMPs have only been in place since 1989, the majority of PTCT’s road system was constructed without the benefit of modern standards, including those for road drainage, erosion control, and fish passage thro ugh culverts. The HCP will require the company to inspect its entire road system in the next 5 years, and bring all old roads into compliance with contemporary BMPs within 10 to 15 years. Once in compliance, the HCP sets maximum intervals for road re-inspection and necessary maintenance. Roads that PCTC does not need for long-term forest management (i.e., surplus roads) will be “abandoned” within the same 10 to 15 years as road upgrades. To be abandoned, several criteria need to be met. These include blocking the ro ad to vehicles, removing culverts and pulling back and reshaping fills at stream crossings, reve getating road surfaces and adding extensive road tread drainage, and stabilizing landslide prone segments through total or partial recontouring.B3 Finally, the plan also requires extensive re search and monitoring to see that the road management system specified in the HCP is working to reduce sediment delivery to streams. This will include preparing sediment budgets in numerous watersheds, monitoring trends in spawning gravel, and validating coefficients used in road sediment models. B.3 Watershed/Landscape Assessment Approaches The basic premise of watershed and landscape based assessment and management systems is that trained evaluators can develop an understanding of watershed and stream processes at work, and an understanding of cause-and-effect relationships between disturbance and stream conditions based on direct observation of stream and watershed conditions, both historic and current, and application of observations within predictive models where appropriate. Current stream conditions are determined, effects of future forest practices are anticipated, and management practices that correct or prevent adverse conditions are developed. B.3.1 Washington Watershed Assessment Process Washington’s watershed analysis approach to watershed management is based on biological and physical inventories of watershed conditions. It is a collaborative process involving resource scientists and managers representing landowners, agencies, tribes, and other interested citizens. Both the assessment and the management process based on assessment findings are highly structured and defined within the Forest Prac tices Act and its implementing rules, and are designed to be repeated and adaptive, as illustrated in Figure B.1.

Public Resources Resource Assessment Prescription Process Effectiveness Monitoring

Feedback for Adaptive Improvement Watershed Processes

Information Area-specific prescriptions

–

regulator y

–

voluntar y activities (BMPs)

watershed processes

resources Management Actions

Predictions and hypotheses of mgmt. actions on

resources

Figure B.1. The Major Components of Washington Watershed Analysis
In Washington’s system for management of road erosion and sediment delivery impacts, roads are field inventoried and the data are used with simple spreadsheet based models that quantifyB4 erosion and sediment delivery in comparison to estimates of natural background watershed sediment delivery. When delivery is considered to be too high, an adverse condition exists that must be addressed with management prescriptions designed to alleviate the condition (see Section 2.7). These prescriptions are developed by local land managers and agencies, must address the specific areas of hazard and resource c oncern identified by the scientific assessments, and are subject to public review and appeal prior to final acceptance of the plan. B.3.2 Idaho Cumulative Watershed Effects Process The objective of Idaho’s Cumul ative Watershed Effects (CWE) assessment and forest practices management process is to lead landowners to conduct future forest practices according to three “staged” criteria (IDL 2000b): 1) In watersheds where beneficial uses are not supported as a result of forest practices and are not improving, mitigation and rehabilitation activities must be conducted in conjunction with current forest practice activities so that, in bala nce, a generally improving trend is maintained until adverse conditions no longer exist. 2) In watersheds where beneficial uses are not supported as a result of forest practices but conditions are improving, activities must be conducted in a way that does not interrupt this improving trend. 3) In watersheds where beneficial uses are supported, forest practices will be designed to prevent loss of this support. The Idaho assessment procedures are designed to detect the presence of adverse watershed or stream conditions, to identify causes for the cond itions, and to identify actions that will correct and prevent existing and potential future problems. The result of implementation of the CWE process in a watershed is the development of ma ndatory special rules for the watershed, called Cumulative Watershed Effects Management Practic es, that are authorized by the state’s Forest Practices Act and are enforced by the Idaho Department of Lands (IDL). As in Washington, roads in Idaho watersheds are inventoried, and although based on a qualitative rating of erosion and delivery of sediment to streams, road conditions leading to adverse instream conditions must be corrected until the qualitative rating score is reduced to within the range considered to be acceptable. B.3.3 California Sustained Yield Plans In California, a Sustained Yield Plan (SYP) is an option for the landowner to supplement the Timber Harvest Plan (THP) process, but does not replace the THP. The SYP provides analysis of long-term issues across the landscape, such as sustained timber production, cumulative watershed effects, and fish and wildlife concerns. The watershed assessment portion of the SYP must include an analysis of potential adverse impacts of planned forestry operations, including impacts on water quality. Specifically, the SYP must include 1) identification of unstable areas and unstable soils that are either actively or potentially discharging sediment; 2) a map of existing roads and the approximate location and mileage of proposed new, reconstructed, and abandoned roads; and 3) a general description ofB5 existing sources of erosion and areas known to be sensitive to ground disturbance. The SYP must also provide a discussion of feasible measures to avoid significant adverse impacts. Once the SYP is approved by the California Department of Forestry, the THP can incorporate findings of the SYP to address issues that we re identified. The THP may rely on the SYP analysis as long as the THP is consistent with the measures set forth in the SYP. If the THP involves issues not discussed in the SYP, the THP must address those issues and conform to the Forest Practices Rules. B.3.4 Oregon Watershed Assessment Process The Oregon watershed assessment process is desi gned to identify how natural processes and human activities affect fish habitat and water quality, and to ev aluate the cumulative effects of land management practices over time. Although the process does not include development of site specific watershed management prescri ptions, it provides the information necessary for development of action plans and monitoring strategies for protecting and improving fish habitat and water quality. The assessment provides broad-scale screening and is developed by local citizens with some assistance from technical experts using the assessment manual’s “cookbook” procedures for compilation and evaluation of information about watersheds. The procedure concludes with development of a Watershed Condition Evaluation and Monitoring Plan. A standard list of Critical Questions is addre ssed for each of six watershed characterization modules, as shown in Figure B.2.

Watershed Watershed Watershed Description Characterization Assessment Hydrology and

Water Use

Riparian/ Wetlands

Sediment Sources

Channel Modification

Water Quality Start-up and Identification of Watershed Issues Watershed Condition Evaluation

Monitoring Plan Historical conditions

Channel Habitat Type Classification

Fish and Fish Habitat Figure B.2. Oregon’s Watershed Assessment ApproachB6 Road erosion and sediment delivery are evaluated as a component of a broad sediment source assessment that identifies where human caused se diment increases are most severe, as well as priority restoration opportunities. The assessment manual provides highly structured and organized procedures for evaluation of landslide hazards, road surface erosion, and stream culvert capacity and condition. Roads are inventoried using Oregon Department of Forestry procedures that are available online at www.odf.state.or.us/FP/default.htm. B.4 Special Issue Management Systems In some cases, management systems evolve around a specific issue or certain species of concern. Examples of this include Habitat Conservation Plans (HCPs), the Oregon Plan for Salmon and Watersheds, Washington State’s Forest and Fish Agreement, and the Idaho Antidegradation Agreement.

B.4.1 Habitat Conservation Plans Section 9 of the 1973 Endangered Species Act (ESA) notes that it is unlawful to “take” endangered species, with the definition of “take” including, “...harass, harm, pursue, hunt, shoot, wound, kill, trap, capture or collect...” Regulations under Section 4 of the Act clarify that “harm” in the definition of “take” includes “significant habitat modification.” In one of the few amendments to the 1973 ESA, Congress modified Section 10 in 1982 to permit “take” for listed species incidental to such othe rwise lawful activities as grazing, farming, or logging. Each application for such an incidental take per mit must be accompanied by a “conservation plan.” There is no requirement that any landowner or agency seek a Habitat Conservation Plan (HCP), but the process is intended to be proactive and creative, with the landowner taking the initiative to obtain the HCP and suggest the habitat conservation measures designed to avoid take. The legal assurances provided by an HCP are not without cost – both in terms of the cash outlay necessary for the completion of the agreement and the delays and modifications to land uses that might be required in exchange for the HCP. The HCP for native fish species developed by Plum Creek Timber Company as described in Section B.2.1 is one example of an HCP that addresses existing and potential future road impacts through comprehensive assessment and inventory followed by implementation of forceful (and expensive) road maintenance and construction requirements. B.4.2 Oregon Plan for Salmon and Watersheds Several Evolutionarily Significant Units of salmon and steelhead have been listed in recent years under the ESA in numerous rivers of coastal and interior Oregon. Under sponsorship of the state’s Governor, Oregon has developed its Plan for Salmon and Watersheds. The key elements of the Oregon Plan are: 1) an ecosystem approach that requires systematic consideration of the full range of attributes of aquatic health; 2) a focus on reversing factors for decline and meeting objectives that address those factors; 3) use of adaptive management and a comprehensive monitoring strategy; and 4) building citizens and constituent groups into the restoration process. Several forest land initiatives have been implemented, including development of the watershed assessment process (OWEB 1999), development of standard road inventory and assessment procedures (ODF undated), and development of training materials for landowners, including theB7 Forest Road Management Handbook (ODF 2000). These procedures emphasize design and construction of culverts to ensure fish passage, along with road maintenance and repairs to prevent surface erosion, washouts, and road failure associated landslides. Several watershed assessments using the Oregon procedures have been completed and many more are in progress. Many members of the Oregon Forest Industry Council and smaller forest landowners have voluntarily completed the required inventories and have initiated rehabilitation of road systems to address existing adverse circumstances (ODF 2000). B.4.3 Washington Forest and Fish Agreement In 1986, the timber industry, tribes, the state, and the environmental community agreed to resolve contentious forest practices problems through negotiations, resulting in Washington’s watershed assessment process and several stream and landscape research efforts. As a result of research findings and common findings within many of the completed watershed analyses, the Timber/Fish/Wildlife (TFW) parties, expanded to include federal and local governments, began working together again to address ESA listings, 660 streams included on the 303(d) list of water quality limited water bodies, and the cost and uncertainty attendant upon timber acquisitions and harvest activities. Agreement was reached and recommended to the Forest Practices Board and the Governor’s Salmon Recovery Office in February 1999. The recommendations were subsequently adopted as Emergency Forest Practices Rules. These rules substantially modified the then-existing forest practices rules in such important areas as stream classification, riparian management requirements, management of unstable slopes, and road management. Under the agreement and the subsequent Emergency Rules, the road management policy is to maintain or provide passage for fish in all life stages, provide for the passage of some woody debris, meet water quality standard s, control sediment delivery, protect streambank stability, and divert most road runoff to the forest floor. Perhaps the most comprehensive of these new rules is that all landowners are now required to develop and submit for public review and Washington Department of Natural Resources approval formal road maintenance and abandonment plans for their entire ownership and road system within specified time frames. Requirements to inventory all stream crossing culverts and to replace or correct those with fish passage problems are included. Culverts not passing the now-required 100 year flood flow must be replaced at the end of their useful life. The new rules also contain comprehensive location, design, maintenance, and abandonment requirements for prevention of both mass and surface erosion. B.4.4 Idaho Antidegradation Agreement The quality of surface water in Idaho and the regulatory scheme for managing it are defined in three “tiers.” The first category is those st reams where the quality of the water exceeds that which is necessary to support such existing “beneficial uses” as salmonid spawning or cold water biota. For these streams, the state’s antidegradation policy allows some lowering of water quality to accommodate logging or other economic activities, as long as the quality is never lowered below that necessary to achieve the beneficial use. The second category of stream includes those where the beneficial uses are not fully supported. These are the waterbodies where state and federal law requires that a TMDL be completed in order to reduce all sources of pollutants to a level where the beneficial uses are once again fully supported. For the portionsB8 within forested watersheds, forestry BMPs are mo re stringent than for the first tier of streams. “Outstanding resource waters” constitute the thir d tier of streams. For these streams, water quality cannot be lowered as the result of any point source discharge or nonpoint activity. Two efforts by the Idaho Department of Environmental Quality (IDEQ) and the Idaho Department of Lands (IDL) are key to determinin g the level of forestry BMPs appropriate to each tier of water quality protection. The rules of Idaho’s Forest Practices Act require a “default” level of BMPs applicable across the state. Every four years, these two agencies conduct an audit of the BMPs to determine if they were effective in maintaining water quality, and rule changes are developed to address instances where practices have been found to be inadequate. IDEQ also monitors streams to determine if benefi cial uses are being met. For streams where the uses are fully supported and there is a history of land uses, the BMPs associated with those uses are, in a general sense, judged to have been effective. For streams where the beneficial uses are not fully supported, a TMDL may be required, and a technical advisory team and citizen group work together to select and imple ment the BMPs needed to assure improvement in water quality.

B.5 Effectiveness of Control Pract ices and Management Systems The effectiveness of BMP based state regulatory systems has been evaluated periodically over the past 20 or so years in some states. Recently, more quantitative procedures have been used to evaluate the effectiveness of company and speci al issue management systems. This section reviews the effectiveness of state BMPs, then recounts a few examples of how special management systems have been applied that have substantially reduced delivery of sediment and runoff to stream systems. B.5.1 Effectiveness of State BMPs As part of their state/EPA agreements, Idaho, Washington, and Montana have conducted formal forest practices water quality audits approximately every four years. More recently, Oregon and California have also begun conducting similar audits. These state audits have assessed both rule compliance and effects on water quality. Idaho and Montana have found that hillslope erosion does not contribute sediment to streams except where disturbance has occurred adjacent to streams, which in most cases has occurred only where activities were found to have been out of compliance with the rules. 6 In some cases, however, roads were found to have contributed sediment to streams in quantities estimated to be potentially harmful to beneficial uses. As a resu lt, rule improvements have been recommended and enacted (Zaroban et al. 1997; IDL 2000a; WFPB 2000). In Idaho, the 1992 IDEQ Water Quality Audit (Hoelscher et al. 1993) concluded that “BMP’s . . were judged to effectively preve nt pollutant delivery to streams 99% of the time,” but that when BMPs were not applied, pollutants, primarily sediment, were delivered to streams 75% of the time. Similarly, the 1996 audit (Zaroban et al. 1997) concluded that “when properly applied and maintained, the management practices described in the Idaho forest practices rules are effective

6 Washington only reports effects associated with rule violations.B9 99% of the time.” However, the most frequent area of non-compliance was related to road construction and/or maintenance; 69% of all cases of non-compliance were associated with road rules. Delivered sediment “was primarily fro m roads with comparatively minor contributions from harvest systems.” Road rules were cited in 84% of those cases where sediment delivery occurred. In Montana, the state has conducted biennial audits of BMP implementation and effectiveness since 1990 (Schultz 1990, 1992; Frank 1994; Mathieus 1996; Fortunate et al. 1998; Ethridge and Heffernan 2000). Over the course of these audits, BMP compliance has continually improved, with statewide BMP application rates of 79%, 88%, 91%, 92%, 94%, and 96% in 1990, 1992, 1994, 1996, 1998, and 2000, respectively. This increase in compliance in Montana is thought to be the result of increased education of landowners, loggers, and forestry professionals (Patrick Heffernan, personal communication). With this increasing level of BMP application over time, water quality impacts have steadily declined and are infrequent where BMPs are fully implemented (Schultz 1990, 1992; Frank 1994; Mathieus 1996; Ethridge and Heffernan 2000). Like Idaho, the most common BMPs that were not fully or properly applied dealt with road drainage and road erosion control. In Washington, the Washington Forest Practices Compliance Report (TFW 1991) does not report any conclusions regarding the effectiveness of properly applied BMPs; it only reports instances of non-compliance and the number of cases in which such non-compliance was judged to result in damage to public resources. The non-compliance rate for harvest related activities was lower than that for roads (62 instances of non-compliance for harvest activities vs. 95 for roads), and the number of cases in which damage to public resources occurred was also lower for harvest than it was for roads (10 instances of damage for harvest vs. 21 for roads). 7 Since 1991, there have been no forest practices audit reports completed for Washington. In Oregon, BMP compliance rates from 1987 to 1996 averaged between 96 and 98% (Dent and Robben 1999). As in Idaho and Montana, the most frequent areas of non-compliance found in the 1998 ODF monitoring were in road construction and/or maintenance (Dent and Robben 1999). Of 20 non-compliant road-related practices, 9 resulted in sediment delivery to streams. The specific non-compliant practices that had the greatest impacts on st reams were related to road drainage or temporary crossings. Of 22 sediment sources identified, 19 were associated with roads; 6 of the 22 sediment sources were estimated to be “incidental” (<1 cubic yard), 10 were “moderate” (1 to 10 cubic yards), and 6 were judged to be “significant” (>10 cubic yards). Additional monitoring by ODF indicated that 31% of the surveyed road length potentially delivered sediment to streams, and that two-th irds of that potential delivery length occurred immediately upslope of live stream crossings (Skaugset and Allen 1998). However, less than half (40%) of that potential delivery length occurred where surface drain spacing exceeded recommended criteria, suggesting that drainage spacing is not sufficient by itself to adequately control sediment delivery from roads. In California, the forest practice rules were generally found to be sufficient to prevent erosion, and 97% of the 727 erosion problem points identified were associated with departures from rule

7 In the majority of cases, damage was judged to be “slight” for both harvest and roads.B10 requirements (CBOF 1999). Rules related to roads had greater than 90% compliance, and most road rule departures were related to drainage and maintenance. However, of 35 mass erosion events documented, 27 were relate d to timber management activities, with 24 of those associated with roads, most often fillslope failures. One of the major conclusions of the monitoring was that “roads and their associated crossings were found to have the greatest potential for delivery of sediment to watercourses,” and that “ where roads are built will remain critical for reducing the likelihood of producing significant sediment input to channels.” Recommendations therefore included greater attention to and better implement ation of rules related to drainage, crossing design, and maintenance. Collectively, these state reports demonstrate that while compliance with BMPs is high, most excursions are associated with roads, and that when road BMPs are not properly applied, sediment delivery to streams is likely. Howe ver, even with full application of state BMPs, sediment delivery from roads can occur. The questions then are “How much sediment delivery?” and “What is its significance?” Watershed assessments are designed to address these questions and, where necessary, to reduce impacts to acceptable levels. B.5.2 LeClerc Creek Mass Wasting A watershed analysis completed by Stimson Lumb er Company for the LeClerc Creek watershed provides an example of mass wasting assessment, development and implementation of mass wasting hazard management prescriptions, and adjustment (adaptive management) of prescriptions with improved information following major runoff events in 1998 and 1999. Forty-six landslides were locate d and several moderate to high hazard mass wasting management units were identified and mapped in 1996 as part of the LeClerc Creek Watershed Assessment (McGreer et al. 1997). One area of the watershed had experienced two road fill failures that resulted in relatively small debris torrents confined to first and second order tributary streams. Based on these failures and characteristics of surrounding areas, a moderate hazard area was designated and mapped in several discontinuous blocks totaling several hundred acres. Management prescriptions for the roads in these units required detailed inspection and preparation of road maintenance plans, installation of additional drainage, and other upgrade measures. However, before these measures c ould be implemented, two additional road failures occurred in the same area as the previous two. Subsequent detailed assessment of the area resulted in a new prescription that required tota l obliteration of all road s and no construction of new roads that lay within the area of particular hazard, as identified by geomorphic characteristics. No subsequent failures have occurred in the watershed. B.5.3 Plum Creek Timber Company HCP As the technical foundation for its Native Fish HCP, PCTC evaluated the potential effectiveness of rigorous sediment delivery control through road upgrading. Several measures were proposed. The most significant upgrade and the measure that could be analyzed most rigorously was addition of road drainage structures. Using an iterative analysis process, road culvert and surface drain structure spacing was speci fied that would substantiall y limit sediment delivery (McGreer et al. 1998). The effectiveness of the approach was then applied to the road systems inventoried in eleven watersheds in Montana, Idaho, and Washington where detailed road erosionB11 assessments had been recently completed. The analysis indicated that construction of additional drainage structures near stream crossings would eliminate 25 to 85% of road sediment delivered to streams in the eleven watersheds evaluated. These measures are now being applied to the 1.7 million acres of PCTC ownership covered by the HCP, where similar results are expected. Implementation and effectiveness monitoring are required by the terms of the HCP to evaluate the effectiveness of these habitat conservation measures. B.5.4 Spruce Creek Road Location and Construction Assessment of an extensive road system in the Spruce Creek watershed of northern Idaho using Washington watershed assessment procedures resulted in estimated sediment delivery from roads of 257 tons/year. Further analysis of site-specific conditions revealed that addition of drainage relief structures near streams would reduce delivery from this existing road system by 149 tons, from 257 tons to 108 tons (McGreer and Schult 1996). Potential sediment delivery from additional roads planned for construction in the watershed was subsequently assessed based on the Washington procedures, coupled with sediment delivery prediction methodology from Megahan and Ketcheson (1996) and based on detailed field data collection for each road segment (McGreer and Schult 1997). Based on standard design measure s consistent with state regulations, three miles of new fullyinsloped road was projected to increase sediment delivery for the watershed by 12% beyond delivery from the existing road system. However, an alysis also revealed that delivery could be reduced by 24%, from 32.0 to 24.3 tons/year, by adding surfacing rock to those sections of road that drain via road ditches directly to streams (i.e., rocking the crossings), and nearly an equivalent reduction (23%) could be achieved with the addition of relief culverts to certain specific road segments. Rocked crossings combined with additional culverts reduced projected sediment delivery to 17.1 tons/year, a 47% reduction, which represents a 7% increase over the amount delivered from the existing road system. In summary, the landowner could choose a number of options for control of sediment from existing and proposed roads that would substantially decrease future sediment delivery to the watershed’s streams while logging and road construction proceeded.

References American Forest and Paper Association (AF&PA). 2000. Sustainable Forestry Initiative SM standard - principles and objectives. Washington, DC: American Forest and Paper Association. 5 p. California State Board of Forestry (CBOF). 1999. Hillslope monitoring program: Monitoring results from 1996 through 1998 . Sacramento, CA: California State Board of Forestry. 70 p. Dent, L., and Robben, J. 1999. Forest practices compliance monitoring project: 1998 pilot study results . Salem, OR: Oregon Department of Forestry. Ethridge, R., and Heffernan, P. 2000. Montana forestry best management practices monitoring – The 2000 forestry BMP audit report . Missoula, MT: Montana Department of Natural Resources and Conservation, Forestry Division. 69 p.B12 Fortunate, N., Heffernan, P., Sanger, K., and Tootell, C. 1998. Montana forestry best management practices implementation monitoring. 1998 forestry BMP audits final report

. Missoula, MT: Montana Department of Natural Resources and Conservation, Forestry Division. Frank, G. 1994. Montana forestry best management practices implementation monitoring. 1994 forestry BMP audits final report . Missoula, MT: Montana Department of Natural Resources and Conservation, Forestry Division. Hoelscher, B., Colla, J., Hanson, M., Heimer, J., McGreer, D., Poirier, S., and Rice, J. 1993. Forest practices water quality audit 1992 . Boise, ID: Idaho Department of Health and Welfare, Division of Environmental Quality. 27 p. plus appendices. Idaho Department of Lands (IDL). 2000a. Rules pertaining to the Idaho Forest Practices Act, Title 38, Chapter 13, Idaho code . Coeur d’Alene, ID: Idaho Department of Lands. 39 p. Idaho Department of Lands (IDL). 2000b. Forest Practices Cumulative Watershed Effects Process for Idaho; Idaho Forest Practices Act . Coeur d’Alene, ID: Idaho Department of Lands. Mathieus, G. 1996. Montana forestry best management practices implementation monitoring. 1996 forestry BMP audits final report . Missoula, MT: Montana Department of Natural Resources and Conservation, Forestry Division. McGreer, D.J., and Schult, D.T. 1997. Spruce Creek sediment delivery; proposed roads

. Project completion report for Plum Creek Timber Company. Lewiston, ID: Western Watershed Analysts. 6 p. McGreer, D.J., and Schult, D.T. 1996. Road sediment assessment for existing roads in the Spruce Creek watershed, northern Idaho . Project completion report for Plum Creek Timber Company. Lewiston, ID: Western Watershed Analysts. McGreer, D.J., Sugden, B., Doughty, K., Metzler, J., and Watson, G. 1997. LeClerc Creek Watershed Assessment . Lewiston, ID: Western Watershed Analysts. 300 p. McGreer, D.J., Sugden, B., and Schult, D. 1998. Surface Erosion and Mass Wasting Assessment and Management Strategies for Plum Creek’s Native Fish Habitat Conservation Plan . Technical Report #3. Columbia Falls, MT: Plum Creek Timber Company. 50 p. Megahan, W.F., and Ketcheson, G.L. 1996. Predicting downslope travel of granitic sediments from forest roads in Idaho. Water Resources Bulletin 32(2): 371-382. Oregon Department of Forestry (ODF). 2000. Forest road management guidebook: Maintenance and repairs to protect fish habitat and water quality . Salem, OR: Oregon Department of Forestry. 32 p. Oregon Department of Forestry (ODF). Undated. Forest road hazard inventory protocol

. Salem, OR: Oregon Department of Forestry. 8 p. plus appendices.B13 Oregon Watershed Enhancement Board (OWEB). 1999. Oregon watershed assessment manual

. Salem, OR: Oregon Watershed Enhancement Board. Plum Creek Timber Company. 2000. Native Fish Habitat Conservation Plan . Seattle, WA: Plum Creek Timber Company. Schultz, B. 1992. Montana forestry best management practices implementation monitoring. 1992 forestry BMP audits final report . Missoula, MT: Montana Department of Natural Resources and Conservation, Forestry Division. Schultz, B. 1990. Montana forestry best management practices implementation monitoring. 1990 forestry BMP audits final report . Missoula, MT: Montana Department of Natural Resources and Conservation, Forestry Division. Skaugset, A., and Allen, M. 1998. Forest road sediment and drainage monitoring project report for private and state lands in western Oregon . Salem, OR: Oregon Department of Forestry. 20 p. Timber/Fish/Wildlife Field Implementation Committee (TFW). 1991. 1991 forest practice compliance survey . Olympia, WA: Washington Department of Natural Resources. 25 p. plus appendices. Washington Forest Practices Board (WFPB). 2000. Forest Practices Act Board Manual

. Olympia, WA: Washington Department of Natural Resources. 212 p. Zaroban, D.W., Love, B., Colla, J., Lesch, G., Heimer, J., Lehner, J., Lukens, B., Poirier, S., Lee, B., and David, K. 1997. Forest practices water quality audit 1996 . Boise, ID: Idaho Department of Health and Welfare, Division of Environmental Quality. 32 p. plus appendices.C1 APPENDIX C

EXAMPLES OF SPECIFIC MANAGEMENT PRACTICES

C.1 Surface Erosion Control Substantial research has been conducted that provides techniques for reduction of forest road erosion (Trimble and Sartz 1957; Packer 1967; Gonsior and Gardner 1971; Burroughs et al. 1976; Berglund 1976; Megahan 1977; Yee and Roelofs 1980; Burroughs and King 1989). Systematic quantification of the benefits of various control t echniques have been built from this research (Burroughs and King 1989; Cline et al. 1981; Potyondy et al. 1991; Ketcheson and Megahan 1996; Elliot et al. 1997). Practices are available for effective treatment of erosion hazards for all major road prism components, e.g., cutslopes, running surfaces, road ditches, fillslopes, and even the area downslope from roads. An excellent summary of road erosion control effectiveness is provided by Burroughs and King (1989), who show that erosion from the entire road prism can be reduced by over 90%. These techniques with a high degree of erosion reduction have practical application for roads located where sediment delivery to streams is of particular concern. Burroughs and King (1989) is a particularly helpful reference to road managers because the percent effectiveness of individual practices is reported, providing road managers with the means of choosing practices that are most practicable and cost effective for their particular location and circumstances. Relationships illustrated by Burroughs and King (1989) include:

With increasing application rates and percent ground cover achieved, treatment of cut and fillslopes with straw, wood chips, rock, hydromulching, or erosion mats can reduce erosion by 80 to 100%, depending on the treatment applied. For instance, straw applied to fillslopes at a rate of 1 ton/acre reduces fills lope erosion by approximately 60%.

Treating road travel surfaces reduces tread erosion by 43 to 77% (see also Burroughs and King 1985; Foltz and Truebe 1995). Surfacing can be a particularly important treatment, because tread erosion usually comprises 50% or more of total delivered road prism erosion, with increasing importance as road traffic increases. Moreover, sediment reduction due to rock surfacing can vary by several-fold depending on hardness and quality of the rock (also Foltz and Burroughs 1990).

Erosion from ditches can be eliminated with rock, and Burroughs and King summarize design principles and criteria.

Development of wheel ruts in roads approximately doubles erosion; surfacing and/or traffic control prevents ruts (see also Foltz and Burroughs 1990; Foltz, Evans, and Truebe 2000).

C.2 Landslide Avoidance Landslides have been reported to be the predominant form of erosion from roads in several studies of steep, hazardous (as evidenced by presence of natural failures) terrain (Megahan and Kidd 1972; Fiksdal 1974; Morrison 1975; O’Loughlin 1972; Swanson and Dyrness 1975).C2 Landslides from road fills or sidecast are the most common type of failure, tend to form debris avalanches or debris flows (often down steep draws and small streams), and are the most destructive to downstream fish-bearing channels (Benda et al. 1997; Furniss et al. 1991; Gonsior and Gardner 1971; Morrison 1975; O’Loughlin 1972; Dyrness 1967). Cutslope failures often block road ditches and divert concentrated water onto fillslopes, contributing to their failure (Dyrness 1967), and discharge of concentrated road drainage water, usually from ditches through relief culverts, onto road fills or naturally unstable bedrock ho llows also contributes to many failures (Benda et al. 1987). These mechanisms point to the solutions:

Avoid slopes and locations with a landslide history.

Avoid headwall and bedrock hollow locations.

Avoid inner valley gorges (the overst eepened slopes adjacent to streams).

Avoid large cuts and fills; minimize volume.

Don’t incorporate woody debris in fills.

Carefully size culverts and install trash racks to prevent plugging, particularly where fill failure could lead to downstream debris flow.

Drain water frequently to avoi d concentration on or below fills and to help avoid further concentration in the event of cutslope failure.

Outslope roads where practical, and consider reshaping insloped roads to outsloped prisms with surface drains when they become inactive.

Eliminate sidecast on steep slopes (those over 50%). Excellent and concise guidelines for recognition of hazardous terrain and landslide prevention are provided by Benda et al. (1997) and Furniss et al. (1991). C.3 Sediment Delivery Reduction The most important step in minimizing the impacts of roads on streams, including both surface and mass erosion (landslides), usually occurs during reconnaissance and route selection. Many, if not most, landslides can be avoided by identifying hazardous slopes and avoiding them. Much, if not most, surface erosion can be prevented from reaching streams by constructing roads in locations where sediment will not reach streams. For sediment from surface erosion, in addition to practices that reduce eroded volume, practices that regulate road runoff amount and distribution or that trap runoff prior to it reaching streams are particularly effective. For example:

Locate the road farther from the stream (Megahan and Ketcheson 1996; Packer 1967; Elliot et al. 1997).

Reducing the length of road that drains directly to streams via ditches at road crossings can substantially reduce total road system sediment delivery (ODF 2000; McGreer et al. 1998).C3Reducing the length of road segment contributing to a relief drain reduces sediment delivery to streams, because the distance the water and sediment travel downslope before being trapped and infiltrated decreases due to decreasing source area for water supplied to the road segment in question (i.e., the volume of water and sediment discharged is smaller and is therefore trapped or infiltrated sooner) (Megahan and Ketcheson 1996; Packer 1967; Elliot et al. 1997).

Increasing obstructions (e.g., rocks, logs, stumps, slash, etc.) on the hillslope below a drain reduces sediment delivery because of increased opportunity for sediment deposition and reduced sediment travel distance (Brake et al. 1997; Megahan and Ketcheson 1996).

Filter windrows constructed at th e toe of fillslopes reduce sed iment leaving the fillslope by approximately 85% (Burroughs and King 1989).

C.4 Runoff Control Runoff control practices are designed to minimize ch anges in the hydrograph caused by the road. These involve minimization of the area of road that directs runoff to stream channels as surface flow. The basic approach involves road prism and drainage system design that prevents concentration of drainage waters and puts water back on forest soils where the runoff infiltrates the soil and sediment can be deposited on slopes before it reaches streams. Practices that accomplish this objective include:

Outslope the road system and eliminate ro ad prisms that are insloped to a ditch.

Locate road systems to minimize stream crossings.

Locate relief culverts or surface drains strategically to minimize the length of the ditch that discharges to streams at crossings. Space them frequently to prevent concentration of discharged water; the larger the volume discharged, the further downslope it travels towards streams prior to infiltration (Ketcheson and Megahan 1996).

References Benda, L., Veldhuisen, C., Miller, D., and Miller, L.R. 1997. Slope instability and forest land managers, a primer and field guide . Seattle, WA: Earth Systems Institute. 74 p. Berglund, E.R. 1976. Seeding to control erosion along forest roads. Extension Circular 885. Corvallis, OR: Oregon State Universi ty Extension Service. 19 p. Brake, D., Molnau, M., and King, J.G. 1997. Sediment transport distances and culvert spacing on logging roads within the Oregon coast mountain range. Minneapolis, MN: ASAE Annual International Meeting, August 10-14, 1997. 12 p. Burroughs, E.R., Chalfant, G.R., and Townsend, M.A. 1976. Slope stability in road construction . Portland, OR: United States Department of the Interior Bureau of Land Management. 102 p.C4 Burroughs, E.R. Jr., and King, J.G. 1989. Reduction of soil erosion on forest roads . General Technical Report INT-264. Ogden, UT: United States Department of Agriculture Forest Service, Intermountain Research Station. 21 p. Burroughs, E.R. Jr., and King, J.G. 1985. Surface erosion control on roads in granitic soils. In: Proceedings of Symposium Sponsored by Committee on Watershed Management/Irrigation and Drainage Division, ASCE, April 30-May 1, 1985, Denver, CO. p. 183-190. Cline, R., Cole, G., Megahan, W., Patten, R., and Potyondy, J. 1981. Guide for predicting sediment yields from forested watersheds . United States Department of Agriculture Forest Service, Northern and Intermountain Regions. Dyrness, C.T. 1967. Mass soil movements in the H. J. Andrews Experimental Forest . Research Paper PNW-42. United States Department of Agriculture Forest Service, Pacific Northwest Forest and Range Experiment Station. 12 p.Elliot, W.J., Graves, S.M., and Hall, D.E. 1997 (draft). Technical documentation to the crossdrain spacing/sediment yield application (X-Drain). Moscow, ID: United States Department of Agriculture Forest Service, Rocky Mountain Research Station. 10 p. Fiksdal, A.J. 1974. A landslide survey of the Stequaleho Creek watershed. Supplement to Final Report FRI-UW-7404. Seattle, WA: University of Washington, Fisheries Research Institute. 7 p. Foltz, R.B., and Burroughs, E.R. 1990. Sediment production from forest roads in wheel ruts. In: Proceedings, Watershed Planning and Analysis in Action Symposium, Irrigation and Drainage Conference, American Society of Civil Engineers . Durango, CO. p. 266-275. Foltz, R.B., and Truebe, M.A. 1995. Effect of aggregate quality on sediment production from a forest road. In: Proceedings of the Sixth International Conference on Low-Volume Roads

. June 25-29, 1995, Minneapolis, MN. p. 49-58. Foltz, R.B., Evans, G.L., and Truebe, M.A. 2000 Relationship of forest toad aggregate test properties to sediment production. In Proceedings ASCE Conference on Watershed Management, June 20-24,2000. Fort Collins, CO: Colorado State University. Furniss, M.J., Roelofs, T.D., and Yee, C.S. 1991. Road construction and maintenance. In: W.R. Meehan (ed). Influences of Forest and Rangeland Management on Salmonid Fishes and Their Habitats . American Fisheries Society Special Publication 19. p. 297-323. Gonsior, M.J., and Gardner, R.B. 1971. Investigation of slope failures in the Idaho Batholith

. Research Paper INT-97. Ogden, UT: United States Department of Agriculture Forest Service, Intermountain Forest and Range Experiment Station. 34 p. Ketcheson, G.L., and Megahan, W.F. 1996. Sediment production and downslope sediment transport from forest roads in granitic watersheds . Research Paper INT-RP-486. Ogden, UT: United States Department of Agriculture Forest Service, Intermountain Research Station. 11 p.C5 McGreer, D.J., Sugden, B., and Schult, D. 1998. Surface Erosion and Mass Wasting Assessment and Management Strategies for Plum Creek’s Native Fish Habitat Conservation Plan . Technical Report #3. Columbia Falls, MT: Plum Creek Timber Company. 50 p. Megahan, W.F. 1977. Reducing erosional impacts of roads. In: Guidelines for Watershed Management, FAO Conservation Guide . Rome: Food and Agriculture Organization of the United Nations. Megahan, W.F., and Ketcheson, G.L. 1996. Predicting downslope travel of granitic sediments from forest roads in Idaho. Water Resources Bulletin 32(2): 371-382. Megahan, W.F., and Kidd, W.J. 1972. Effect of logging roads on sediment production rates in the Idaho Batholith . Research Paper INT-123. Ogden, UT: United States Department of Agriculture Forest Service, Intermountain Forest and Range Experiment Station. 14 p. Morrison, P.H. 1975. Ecological and geomorphological consequences of mass movements in the Alder Creek watershed and implications for forest land management . Bachelor’s thesis. Eugene, OR: University of Oregon. 102 p. O’Loughlin, C.L. 1972. The stability of steepland forest soils in the coast mountains, southwest British Columbia. Doctoral dissertation. Vancouver, BC: University of British Columbia. 147 p. Oregon Department of Forestry (ODF). 2000. Forest road management guidebook: Maintenance and repairs to protect fish habitat and water quality . Salem, OR: Oregon Department of Forestry. 32 p. Packer, P.E. 1967. Criteria for designing and locating logging roads to control sediment. Forest Science 13(1): 2-18. Potyondy, J.P., Cole, G.F., and Megahan, W.F. 1991. A procedure for estimating sediment yields from forested watersheds. In: S.S. Fan and Y.H. Kiuo (eds). Proceedings of the Fifth Federal Interagency Sedimentation Conference , March 18-21, 1991, Las Vegas, NV. p. 12- 46 thru 12-54. Swanson, F.J., and Dyrness, C.T. 1975. Impact of clear-cutting and road construction on soil erosion by landslides in the western Cascade Range, Oregon. Geology 3(7): 393-396. Trimble, G.R., and Sartz, R.S. 1957. How far from a stream should a logging road be located? Journal of Forestry 55: 339-341. Yee, C.S., and Roelofs, T.D. 1980. Planning forest roads to protect salmonid habitat . General Technical Report PNW-109. Portland, OR: United States Department of Agriculture Forest Service, Pacific Northwest Forest and Range Experiment Station. 26 p.