Columbia Slough Macrophyte Survey

2021 represented the 7th year that Mosaic led aquatic plant surveys in the Middle and Upper Columbia Slough Watersheds of Portland, OR. Over 20 miles of waterways were surveyed for 44 target non-native macrophytes and 32 plots were established to quantify the aquatic plant community, both native and non-native. Data was collected through grab samples and visual percent cover estimates. Species were separated by growth habit (floating, emergent, submersed) and native status. Mosaic Ecology botanists used dichotomous keys and worked with regional herbaria to identify unknown plants. A total of 58 aquatic species were identified. Plot data was sent to The City of Portland for further analyses and to be incorporated into their watershed health assessment. Subsequent treatment and restoration plans were created and implemented by Mosaic Ecology.     

By using GPS data and detailed maps we were able to prioritize populations of non-native macrophytes as well as specific stretches of waterway. Through the application of IPM strategies and mobilizing crews by boat, over the last seven years we’ve been able to identify and quickly remove the first known populations of Ludwigia peploides, Pistia stratiotes and Eichhornia crassipes in the Middle and Upper Columbia Slough Watersheds prior to establishment and spread.