Lower Glenbrook Dam prior to removal of east arm

Point Reyes National Seashore completed the Glenbrook Quarry Restoration and Dam Removal Project within the Estero de Limantour during the week of October 5, 2009. The 15-foot high, 600-foot long Lower Glenbrook Dam was constructed in 1960 with material mined from the adjacent hillslopes and failed in 1982 during a major storm event. Contractors removed approximately 19,000 cubic yards of the former dam, using that material to restore the abandoned mine land features within Wilderness.

The excavation of the remaining dam from the estuary restored a priority abandoned mine land site and removed a non-conforming structure from the Phillip Burton Wilderness. The project reestablished the natural hydrologic and shoreline regime in Limantour Estero, part of the Phillip Burton Wilderness. Limantour Estero is a biologically rich estuary that was recently designated a Marine Reserve through the California Marine Life Protection Act.

Site of former Glenbrook Dam at high tide, October 2009

Removal of the fill from the estuary returned natural hydrologic conditions to the estuarine habitat at Point Reyes National Seashore by removing remaining infrastructure which impeded the development and function of the tidal marshplain. The project area is subject to sea level rise and restoration of natural process within this estuary is a climate change adaptation strategy to ensure maintenance of a healthy and functional estuarine ecosystem. Funding for this project was provided through the NPS Abandoned Mine Lands program, the Bella Vista Foundation, and Point Reyes National Seashore Association.

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The Restoration of the Lower Glenbrook Quarry and Dam Removal at Turney Point Environmental Assessment (1,155 KB PDF) examined alternative means to restore natural hydrologic function and assessed the potential environmental effects of the implementation of each strategy. This Environmental Assessment addressed removal of the remnant portions of the Lower Glenbrook Dam, which breached in 1982, and restoration of the adjacent spillway and quarry areas used to construct the original dam. The remains of the dam and disturbed lands associated with the quarry and spillway were considered a non-conforming structure in the Philip Burton Wilderness. The project is intended to restore natural conditions and enhance estuarine habitat in this portion of Drakes Estero. The project did not result in habitat conversion and was consistent with other restoration efforts in the park such as the Coastal Watershed Restoration and Giacomini Wetland Restoration. This Environmental Assessment evaluated the potential environmental consequences of three alternative strategies for implementing the Lower Glenbrook Quarry and Dam Removal at Turney Point Project.

The public comment period for the project EA closed February 22, 2008. As a result of the public review process and consultation with regulatory agencies the National Park Service determined that this project would not result in significant impacts. A Finding of No Significant Impact (FONSI) was completed and signed by the acting Regional Director on May 19, 2008.

Point Reyes National Seashore Completes Restoration within the Phillip Burton Wilderness - October 9, 2009 (157 KB PDF)

Glenbrook Quarry Restoration and Dam Removal: Restoring Natural Process in the Phillip Burton Wilderness slideshow - October 9, 2009 (7,712 KB PDF)

Finding of No Significant Impact - May 19, 2009 (239 KB PDF)

Environmental Assessment - January 18, 2008 (1,155 KB PDF)

Letter to Interested Parties - January 18, 2008 (44 KB PDF)

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