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1.6 Local Conditions How and where trails can be constructed and maintained is strongly influenced by local climate, topography, and regulatory conditions. Some of the more important of these factors in the Eugene area include: Climate: The climate in Eugene is characterized by cool, wet winters and warm, dry summers. The typical yearly distribution of precipitation includes about 50 percent of the annual total falling from December through February, with lesser amounts in the spring and fall months, and very little precipitation falling duri~g summer. The relatively mild climate is well suited for recreational trail use throughout the year. However, the condition of some trails can deteriorate quickly during the winter due to regular rainfall, especially in heavy use areas and areas with heavy clay soils. Many trails Eugene's current system have been constructed with a gravel base and drainage features and are well suited for all-season use. Other trails have not been constructed for sustainable all -weather use, and are becoming degraded due to winter use. Topography: The landform of the Eugene area is diverse yet well -defined. In general, the southerly portion of the planning area is characterized by the steep slopes of the South Hills Ridge/ine Area, which extends east and west from Spencer Butte. Much of north and west Eugene consists of the relatively flat valley bottoms of the Willamette River, McKenzie River, and Amazon Creek floodplains or historic floodplains. Nearly 75 percent of the land within the planning area has slopes of five percent or less. Slopes in excess of 25 percent make up approximately 5 percent of the planning area, almost all of which is in the South Hills Ridgeline Area. In the steeper terrain, trails are often sited along ridgetops where feasible and frequently require switchbacks to maintain a suitable grade . Soils: Many of the soil types found in the Eugene area have a high clay content and tend to be poorly drained. Nearly 80 percent of the soils within the trails planning area are rated as having a very slow-to moderately slow-rate of permeability. These poorly drained soils become easily saturated and retain water over longer period of time, requiring special drainage and surfacing measures for trail construction. The Willamette River corridor and the Willakenzie neighborhood in north Eugene generally have the best drained soils with higher sand and gravel content. In these areas, drainage may be less of an issue. Wetlands and Waterways: Rivers, streams, and wetlands are prevalent throughout much of Eugene and trail siting in proximity to these areas can be challenging due to physical and regulatory constraints. Typically trail planning and construction within these areas is much more time consuming and expensive. The City's land use code mandates that overall impacts be limited, and in many cases trails must be sited a certain distance from these natural features or special measures or additional steps be taken to limit or offset impacts. Often specialists must be consulted to determine actual boundaries and habitat types, and additional permitting and planning processes must be undertaken, including state and federal permits. Conservation Easements: Property acquired by the City can come with specific easement language restricting trail construction and public access in perpetuity. Sometimes, Federal grants and other funds used to acquire natural areas can require these types of easement restrictions. Conservation easements that limit formal public access most typically occur when the properties are obtained primarily or solely for conservation of endangered species or threatened habitats, and where there is concern that public trails would likely harm the target species or habitats. Eugene Trails Plan -2018 Page 11