Ephemeral streams are small headwater streams that only experience streamflow in response to a precipitation event. Due to their highly complex and dynamic spatial and temporal nature, ephemeral streams have been difficult to monitor and are in general poorly understood. This research implemented an extensive network of recently developed electrical resistance sensors to monitor ephemeral streamflow in a Southern Ontario watershed, located in Guelph, Ontario. From this data, patterns of stream network expansion and contraction were determined. Further analysis examined a series of spatial and temporal variables that were monitored to explain the occurrence of ephemeral channel activity through binary logistic regression. The results suggest that the most common patterns of network expansion and contraction at the study site are incomplete coalescence and disintegration, respectively. Analysis of the primary controls on ephemeral streamflow showed only weak relationships, suggesting that there are more complex processes at work in these ephemeral streams. This research has implications for improving ephemeral streamflow monitoring in the future, which will be important for developing and implementing meaningful conservation and management strategies.