Permit conditions require burial of culverts a minimum of 12 inches or 20% in order to prevent “perched” pipes which could hinder aquatic organisms’ passage. Observation indicated that burying the culverts resulted in stream instability including headcutting downstream in some streams. This project will document whether this instability has occurred at 11 culverts encompassing a variety of topographic and hydraulic conditions, stream channel variations, and locations. Documentation will include longitudinal and cross sectional surveys of the stream channels upstream and downstream of the culverts, which will be compared to similar surveys conducted in 2005. If the survey and geomorphic data show the stream channel has not changed significantly, then it will be considered stable. Rainfall and land use data for the period between assessments will be obtained to document changes that could have caused stream instability. An estimate of bank erosion hazard will also be conducted using the BEHI method. An assessment of aquatic organisms¿ ease of passage through the culverts will also be determined. A report synthesizing all of the results will be prepared and submitted along with spreadsheets of the data.
