Aerial Mapping of the Colorado River over Memorial Day Weekend Release Date: May 24, 2021 The USGS will collect high-resolution aerial imagery over Grand Canyon National Park for approximately one week beginning Saturday, May 29, to document, observe and track long-term ecosystem changes in the Colorado River. Visitors along the Colorado River in Glen Canyon National Recreation Area and Grand Canyon National Park may see and hear aircraft more frequently during this time. Water released from Glen Canyon Dam will be reduced to 8,000 cubic feet per second beginning Friday, May 28, and will continue for the duration of the image collection. This period of steady flows will not affect the monthly or annual release volumes from Lake Powell through Glen Canyon Dam. The flows should not cause a disturbance to recreational river users, as they will stay within the normal range of operations for this time of year.