Hydraulic connection between surface water and groundwater is an important consideration when evaluating environmental flow needs. This study evaluated the potential for using temporal changes in the concentration of radon-222 (222Rn) in shallow groundwater as a proxy for hydraulic connectivity. Vaseux Creek traverses the southern edge of an alluvial fan in the semi-arid South Okanagan Valley, British Columbia. Stream flow is perennial at the fan apex and intermittent in the distal fan from summer through winter. Surface water and groundwater were sampled at co-located stations from November 2021 to February 2023. Sampling was conducted weekly to monthly. Connectivity was initially assessed by comparing water levels in the creek to water levels in adjacent wells. During freshet, dissolved 222Rn exhibited the opposite behaviour at connected and disconnected sites. At the former, 222Rn decreased simultaneously with electrical conductivity (EC) and a rise in stream level. Ingress of freshet water was evident in the stable isotope composition of groundwater. In contrast, at a putatively disconnected site, 222Rn increased in groundwater as stream level rose during freshet and EC decreased in both stream water and groundwater. At a third site, the relationship between 222Rn and EC indicated a switch from disconnected to connected during freshet. On-going study will examine the mechanisms by which 222Rn increases at disconnected sites, the sensitivity of the 222Rn tracer approach to well placement, and the need for other types of supporting data to ensure accurate assessment of connectivity.