Gales Creek Large Woody Debris Inventory Report

LWD surveys in five reaches of Gales Creek were conducted using methods developed for habitat restoration by the California Department of Fish and Game (Flosi et al. 1998). Selected survey reaches were divided into 200-ft intervals and one thousand feet of each reach were surveyed for LWD, except for GL06 which was only 900 ft in length and GL09 where 1,100 ft were surveyed (Table 1; Figure 1). In reaches greater than 1,000 ft (GL02, GL08 and GL09), a minimum of five intervals were randomly selected for sampling (Table 1; Figure 1). This design allows for comparison of each 200 ft section of stream as a replicate, and the surveyed segments of each reach can be combined to make generalizations about each reach. Every linear foot of each reach was not surveyed, thus LWD, debris jams, weirs and other observations within the reaches may have not been counted in these surveys. These items were counted within the surveyed 200 ft segments only. Data were tallied and averaged for each reach individually and combined for an overall analysis of wood in the surveyed reaches.

Surveyors traveled upstream through each reach with a hip chain, marking habitat units (pools, riffles and glides) and tallying all LWD pieces. Each piece of wood ≥ 1 foot in diameter and ≥ 6 feet in length and root wads ≥ 1 foot were tallied. Wood pieces and trees within the recruitment zone were also tallied and characterized as live or dead. Live trees were further characterized as being coniferous or deciduous. Debris jams, defined as aggregations of three or more pieces of wood, were located, photographed and noted. Other observations such as the occurrence of beaver dams were also recorded.

In addition to the methods outlined in Flosi et al. (1998), steps were taken to better support the objectives of this study and the Gales Creek watershed. Crews recorded habitat units where debris jams occurred and noted if the jam marked a change in habitat type. Habitat units were defined according to ODFW’s Methods for Stream Habitat Surveys (Leader 2002). The recruitment zone for live trees was defined as 50 feet from the bankfull edge for the survey. Water and air temperature were taken at the beginning of each survey with a handheld thermometer.

Crews recorded the location of the downstream and upstream end of reach and any debris jams by averaging the location on a Garmin 12 handheld GPS unit. Field workers took photos facing into the reach from the downstream and upstream ends and also photographed any notable features (beaver dams, diversions, etc.) throughout the sampled reaches.

Waypoints from the handheld GPS units were overlain on a 2003 color aerial photo of the study area, provided by April Olbrich of the TRWC, in ArcMap 9.1. Point data were joined with a database of the results of the LWD census to create maps for this report.