Red and salt cedars (R/SC), increasingly common trees found in the southern Great Plains, are invasive species that have over the last 50 to 100 years dominated large acreages of rangeland and riparian areas.  R/SC spread rapidly and choke out indigenous vegetation leading to environmental degredation. In arid and semi-arid parts of western Oklahoma, R/SC can utilize limited water resources and impact soil water content, ground water levels, base flow conditions and possibly downstream water resources for urban usage. The objective of this study is to monitor changes in ground water levels and base flow in a one mile interval along the northern Canadian river near Woodward, OK, associated with the removal of cedars in pasture and riparian areas. Shallow (10 to 20 ft) ground water wells established in two transects; one parallel to the river and one perpendicular to the river, will allow monthly monitoring of shallow ground water conditions during and after a systematic removal of R/SC. Cores of the substrate and drill cutting samples will provide stratigraphic and textural information of the study site to be used in flow calculations. Seasonal monitoring of stream baseflow discharge of the Canadian river into and out of the study site will provide insight on potential impact on ground water/surface water interactions and downstream water resources.  Benefits of this project will include an estimate of base flow variation due to the systematic removal of R/SC and impact on downstream water resources.