Ochoco Summit OHV EIS Lookout Mountain/Paulina Districts, Ochoco NF December 28, 2010 Geology and Minerals________________________________ EXISTING CONDITION – Physical Environment The Ochoco Summit OHV Analysis area (301,582 acres) (Table 1) is contained within 9 watersheds. The analysis area is located in the heart of the Ochoco Mountains, stretching from Hwy 26 on Marks Creek on Lookout Mountain District to east of Little Summit Prairie on Paulina District, Ochoco National Forest. All the percentages listed in the report are based on the acres of federal and private land contained in the project boundary. The shaping of the landforms in the watershed are a reflection of the past climate and geologic history of the area. The analysis area is underlain mainly by a mixture of rhyolite, basalt, andesite and sedimentary rocks. The climate 60 million years ago to the present has evolved from a warm moist tropical regime to the temperate four distinct seasons of today. The tectonic movement, uplift of the Blue Mountain anticline and mass wasting processes combined to create the moderately dissected and hummocky terrain which is the predominant landform. Landslides played a major role in the shaping of the watersheds creating large areas of hummocky terrain, seeps, ponds and springs. Present day erosion processes are primarily sheet and rill with minor mass wasting in the form of small landslides, rock topple and slope creep. The watersheds are a groundwater recharge collection area for regional and local aquifers. Mt. Mazama erupted approximately 7,000 years ago, depositing a 1.5 feet thick blanket of volcanic ash across the Ochoco Mountains. This volcanic ash has mixed with the evolving soils. Annual precipitation ranges from 15 to 31 inches per year. The planning area encompasses the Large Meadow Complex, North Slope Ochoco, Scab Stringer and South Slope Ochoco Level 5 Ecoregions (Appendix A) which have a broad range of characteristics. Common to All Alternatives Lithology The Ochoco Summit OHV analysis area lies within portions of 9 separate fifth-field watersheds (Table 1). For the purposes of this project, the lithologies with similar erosion characteristics have been lumped together. The Quaternary alluvium (Qal), landslide terrain (Qls) and fanglomerate (Qf) are moderately to highly erosive, composed of unconsolidated materials, underlies 7% of the planning area. The Quaternary basalt (Qb) and Quaternary/Tertiary basalt (QTb) are more resistant lava flows (<0.01%). The Clarno Formation (Tca), Tertiary sedimentary (Ts) and the John Day Formation (Tsfj) are moderately erosive, being composed of volcanic sandstones, pyroclastic tuff and mudflows, comprises 21% of the planning area. The Tertiary Picture Gorge Basalt ( Tcp), Tertiary volvanic intrusive (Tvi), Tertiary (Tat), Tertiary rhyolite (Tr) and Tertiary (Tct) are primarily resistant to erosion, composed of rhyolite, andesite and basalt flows, comprises 72% of the planning area. The Mesozoic Cretacious Sedimentary units (Ks) are moderately erosive (<0.05%). Table 1 Lithology (acres) across the project planning area by watershed 1 Watershed Quaternary Tertiary Tertiary Mesozoic Total Quaternary (5th Order) Resistant Moderately Resistant Moderately Acres Highly (Qt, QTb) Erosive (Tcp, Erosive (Ks) Erosive acres (Tca, Tsfj, Tat, Tr, acres (Qal, Qf, Ts) acres Tct, Tvi) Qls) acres acres Bridge 5750 0 5664 4027 154 15595 Creek Deep 270 0 0 54292 0 54562 Creek Lower 92 17 696 22805 0 23610 Beaver Creek Lower 0 3 0 21455 0 21457 North Fork Crooked River Mountain 7599 0 6279 5366 0 19244 Creek Paulina 0 0 0 16095 0 16095 Creek Rock Creek 1335 0 0 12845 0 14180 Upper 3325 0 9222 76239 0 88786 North Fork Crooked River Upper 2200 0 42507 3126 0 47833 Ochoco Creek TOTAL 20,571 20 64,368 216,250 154 301,362 (7%) (0.01%) (21%) (72%) (0.05%) Landslide Terrain Although the lithology map shows landslide terrain, the scale of mapping doesn’t always pick up the rest of the dormant or active landslide terrain. Between field investigations and airphoto interpretation, additional acres have been identified for the planning area (Table 2). Table 2 Landslide Terrain by subwatershed (acres) Watershed (5th Active Landslide Dormant Landslide Watershed (5th Percentage (active) Order) (Acres) Terrain (Acres) Order) Total Acres Dormant Bridge Creek 8 9361 15595 (0.05%) 60% Deep Creek 0 642 54562 1.2% Lower Beaver 0 158 23610 0.7% Creek 2 Lower North Fork 0 0 21457 0% Crooked River Mountain Creek 0 8674 19244 45% Paulina Creek 0 23 16095 0.1% Rock Creek 0 1584 14180 11.2% Upper North Fork 0 7446 88786 8.4% Crooked River Upper Ochoco 4 11441 47833 (0.01%) 24% Creek TOTAL 12 39329 301,362 (0.004%) 13% Alternative 1 (No Action) Implementation of Alternative 1 would result in no changes from the current conditions in the Analysis Area. The mileage of open and closed roads, and the resultant road densities, would remain as they are. Maintenance Level 2 roads would be open for mixed use by both highway-legal and non-highway- legal vehicles, but there would be no roads incorporated as portions of any designated trail system. Non-highway-legal vehicles would be prohibited on all roads maintained for passenger car use (Maintenance Level 3, 4, and 5), plus the Maintenance Level 2 roads added to the list for safety reasons. Use of Maintenance Level 1 roads and user-created roads and trails would be subject to decisions resulting from implementation of the 2005 Travel Management Rule on the Ochoco National Forest. Effects Common To All Action Alternatives To varying degrees, each of the three Action Alternatives incorporates the use of National Forest System Roads to provide designated connectivity throughout the Analysis Area within and between portions of the designated trail system. Subsequent to the establishment of the 2005 Travel Management Rule, the Regional Forester of the Pacific Northwest Region issued direction that an Engineering Analysis would be required for any National Forest System Road designated for mixed use (allowing use by both highway- legal and non-highway-legal vehicles). As part of implementation of the Travel Management Rule on the Ochoco National Forest, mixed use analysis has been performed to establish the suitability of allowing mixed use on roads; in the context of their current setting in terms of alignment, width, typical user speed, and presence or absence of traffic control devices. Trail and Stream Intersections For all alternatives, the intersection of the routes and streams was accomplished with a GIS exercise. The identification of the type of stream crossing was based on the stream class. Bridges were identified for all the Class 2 streams and some of the Class 3. Culverts were identified for a good portion of the Class 3 streams. A combination of culverts and fords were proposed for the Class 4 streams. In a few locations, boardwalks were proposed where wet meadows underlie the proposed routes. There were also several areas where the GIS stream alignment and the proposed trail routes intersected an unusually high number of times. Ground checking will most likely show only 1 or 2 intersections. Based on the rough alignment of the proposed routes, the accuracy of the GIS stream routes and the need to verify stream class, the confidence factor for the intersections is 80%. During actual design, the type of stream crossing, location and trail route may alter. Seasonal Closure 3 The Ragar Green Dot closure, established by the ODFW, identifies a network of open and closed roads during the fall deer rifle-hunting season in the eastern portion of the analysis on the east end of the Ochoco Mountains, from Sept. 30 to November 29. In each of the action alternatives, the routes entering into the Ragar Green Dot closure area will have a seasonal closure from Sept. 30 to November 29. For the most years, the wet season will generally start in November, so the actual closure may extend from Sept. 30 through snow melt in the spring for the eastern half of the trails. The western half of the routes will seasonally close when the snow pack covers the system. This generally starts in mid-November or December and continues through April, with the systems drying out in May. This will protect the trails from excessive erosion. Invasive Species Although the actual acres at risk for introduction of new populations and expansion of existing populations are a small percentage of the overall forest acres, an introduction of invasive plants could mean the closure of the source as an aggregate source for the forest, requiring an increase in expenditure for projects to bring in weed free aggregate material from other sources (increased haul costs). The forest is directed to ensure adequate aggregate needs for internal use. One way to accomplish this is to ensure weed free sources. The Ochoco NF has already experienced increased aggregate haul costs for recreation projects due to a material source closure based on a medusahead infestation. For any of the alternatives, the success will be measured in the ability of the districts to monitor and treat new and existing populations, keeping the spread of invasive species minimized, which in turn will help reduce costs to projects because the mineral material will be available locally, with a short haul. Alternative 2 (Proposed Action) Under Alternative 2, a combination of Class 1, Class 2 and Class 3 routes totals to 170 miles of new trail (Table 3) that cross different lithologies with varing resistance to erosion. Segments of the proposed new routes also cross dormant landslide terrain (Table 4). The distribution of the designated OHV trails for this alternative begins on Hwy 26, passing from Hwy 26 to Walton Lake, across the top of Big Summit Prairie to 6 Corners on Paulina District.