During the many years of drives on Maine rivers, such as the Kennebec pictured here, hundreds of thousands of pulp logs sank to the bottom before reaching their destinations. Along with the bark they shed, their remains continue to decay and consume oxygen. They become visible at low tide in the tidal portions of the rivers, but remain hidden further upstream.

Huge cribworks containing rocks, such as these in the Kennebec River, were built to anchor floating booms that guided the logs around obstructions or coves that were likely to stop the flow to the pulp and paper mills downstream. They remain in the rivers, reminders of the bygone era which ended with the last log drive in 1976. Maine rivers were dammed in many places to provide power and to control the flow of water in support of the many mills and related industries along their banks. A historic moment in this legacy occurred on July 1, 1999 when the Edwards Dam on the Kennebec was breached, allowing the river to flow freely through Augusta for the first time in 162 years. During the winter, U.S. Coast Guard icebreakers keep major rivers navigable, primarily for the delivery of fuel by small tankers.