erosion (low, moderate, high), and priority for repair (low, moderate, high). Individual erosion features were photographed and their locations plotted on the Joaquin Miller Park trail map. These data are attached to the corresponding field data sheet. The volume of erosion that has occurred at each site was calculated by measuring the length, width, and depth of the feature with a tape measure. Observations bearing on possible causes of each erosion feature were recorded in a field notebook and summarized on the field data sheet.

The current condition of the watercourses within Joaquin Miller Park was evaluated by walking selected streams and making observations and measurements at trail/stream crossings and along stream banks. The watercourses targeted in this study included; (1) the main channel of Palo Seco Creek; (2) the major tributary of Palo Seco Creek along Cinderella Trail; and (3) the four prominent tributaries that cross the Sequoia Bayview Trail and drain the steep redwood forest in the southern portion of the park. The types of baseline erosion data collected on these watercourses are similar to the baseline erosion data collected at trail erosion sites. The baseline erosion data was used to prioritize individual erosion features for mitigation and future study.

The general health of the redwood forest overstory and understory was assessed by field surveys around the trail areas within the areas of concern. The overstory surveys consisted of two types of survey methods. First, a general random ocular survey was conducted to assess the overall health of the trees and to identify areas that may warrant additional investigation. Observations were made for tree vigor, mechanical damage, and tree pathogens. Second, specific trees were selected to sample for age, growth rates, and defect observations. Selected redwood trees were sampled for growth rates by taking sample cores with an increment borer and measuring radial growth. Understory surveys were performed to identify native and non-native plant species and to assess traffic impacts on the health of the vegetation.

RESULTS

Trails

Sediment sources and erosion problems were documented along the trail network and watercourses in Joaquin Miller Park, specifically in 11 areas of concern identified by the City of Oakland, labeled A through K on Figure 1. Trails in these areas of concern are cut into a variety of different soil and rock conditions, and they range from flat to steep. Additionally, the trails traverse several different ecosystems, mainly redwood forest, oak woodland forest, and grassland. Trails in the more popular areas of the park have experienced more use than trails in less popular areas. "Bootleg trails" (trails created by users and not maintained by the park) and trails not included in the City of Oakland's specific areas of concern also were observed.

The majority of the specified trails have experienced a considerable amount of use over the years, and as a consequence are well compacted. Many of these trails were constructed with adequate grade, alinement, and width characteristics. Because of tight