The dominant source of the fine sediment impairing water quality in the Portneuf River comes from Marsh Creek, an agriculturally-impacted tributary. Since the 1980s, a range of initiatives and conservation projects have aimed to reduce the sediment load in Marsh Creek, but like many stream restoration efforts, quantitative post-project assessment is lacking. Such data are critical for understanding project effectiveness and guiding future efforts. We evaluate historic data sources to assess changes in sediment loads over time in Marsh Creek. We do this by linking the progressive implementation of best management practices (BMPs) with sparse water quality and quantity records, aerial imagery, and landowner interviews. From this integrated analysis, we first quantify historic changes in channel form, riparian vegetation, and land use practice along Marsh Creek. Second, we quantify the social and ecological costs and benefits of past conservation and restoration projects from landowner perspectives in order to more efficiently guide future efforts.
Results/Conclusions
Analysis is ongoing, but initial results yield two important findings. First, high-resolution digital elevation models and aerial photograph analysis provide little evidence of historic stream meanders, suggesting instead that Marsh Creek initially existed as riverine wetland system. Human induced changes in the channel form, location and water use have reduced river-floodplain connectivity. Second, the implementation of BMPs throughout the watershed has historically been fragmented in space and time. Agency personnel aim to target projects more strategically to improve conservation benefits. Our continuing work focuses on assessing the effectiveness of past stream conservation and restoration projects by analyzing water quality records and conducting landowner interviews. Additionally, data from landowner interviews will be helpful for agency personnel to effectively target interested landowners and successful conservation actions in high priority areas.