See and avoid works well most of the time. It's the rest of the time that needs to be addressed. Normally one tower for fixed wing and another for helo traffic during busy hours at this field. One was apparently released early so the remaining on took on a high workload. That may have been the first hole in the cheese. Stepping back the whole scenario seems to be an accident waiting to happen. The Feds, local authorities or whomever should have dictated a minimum of two tower controllers during these high workload time frames.