High mountain lakes are unique ecosystems that are especially vulnerable to the threats of climate change and introduced species, due to their high elevation and isolation from other waterbodies. Benthic macroinvertebrates are a large part of the aquatic community of these lakes and are used in aquatic community bioassessment as indicators of disturbance and biological integrity. Temporal beta diversity, change in species composition at a site over time, is an important metric in characterizing communities and understanding how ecosystems change over time. Temporal beta-diversity index scores range between 0 (completely similar) representing no species losses or gains and 1 (completely dissimilar) representing no shared species between the samples. Despite its importance, temporal beta diversity analyses have been relatively rare in the published literature due to the need for long-term datasets. Using long-term monitoring data collected by the National Park Service at twelve mountain lakes in Washington State, USA, community data representing a series of 12-15 years were analyzed. Watersheds varied from nearly completely forested to sparsely forested alpine watersheds. Years of high and low snowpack were captured in the dataset as well as multiple removals of introduced fish populations by mechanical and chemical means. Using the Jaccard index, temporal beta diversity values averaged ~0.5 across the long-term monitoring lakes, with significant variability across lakes. The results of this study indicate that these mountain lake macroinvertebrate communities exhibited relatively high rates of taxa turnover, both with and in the absence of significant disturbance. This study helps us to understand how mountain lake communities change over time and will help inform future lake management and research.