Anza Trail Blog

Restoring Healthy Wetlands Along the Anza Trail

by Hale Sargent, Anza Trail Interpretive Specialist

Tagged as:   Arizona , California , Historic Sites , Nature , San Francisco County , Santa Cruz County

Las Lagunas de Anza

The Anza Trail is bookended by a lake and a wetland. Symbols of life and sustenance, they served as the southernmost and northernmost campsites to the Anza Expedition within the present-day U.S. 

Both were once threatened by development and industrialization. But gladly, today both are making a comeback as sites of environmental education and community conservation.

Las Lagunas de Anza in Nogales, Ariz., is the first historic Anza Expedition campsite in the U.S. On October 14, 1775, the colonists stopped here for a night, just two weeks into their journey, still wary of Apache raids and the longer route that lay ahead (see on map).

For Las Lagunas, the future was equally perilous. Today we value wetlands for their biodiversity, but for much of the modern era, wetlands were denigrated for their mosquitos and seen as a barrier to development. According to the U.S. Geological Survey, more than half of America’s original wetlands have been drained, filled, converted to farmland or worse.

Indeed, though less than 1% of Arizona’s landscape includes wetlands, Las Lagunas became a dumping ground over time. John “Tony” Sedgwick, whose family owned the land for decades, began its rehabilitation in 2009.

Working with volunteers, as well local, state, and federal agencies, Tony has made Las Lagunas de Anza an outdoor classroom for environmental education. With the staff and volunteers of the Santa Fe Ranch Foundation, he has removed debris, thinned overgrown vegetation, planted native gardens, and welcomed local youth to take part every step of the way. In recognition of his efforts, the Environmental Law Institute honored Tony with the National Wetlands Award for Landowner Stewardship in 2012.

Las Lagunas continues to play an important role for the Anza Trail as home base for the Anza Trail Ambassadors, a youth development program that combines environmental stewardship with culture and history.

About 1,200 miles away, the Anza Trail arrives at the Golden Gate, where another body of water is undergoing its own revitalization. 

“We arrived at half past ten at the mouth of the port of San Francisco,” Anza wrote upon reaching his destination on March 27, 1776. “Here we halted on the banks of a lake which until today has been regarded as a lagoon, because its outlet into the sea had not been seen, but it has a stream sufficient for a mill.”

This lake, Mountain Lake, served as campsite for Anza and his scouting party when they arrived to site the future presidio and mission. The Ohlone Indians were likely the first humans to drink the lake’s waters, and today it is one of the few remaining natural lakes in San Francisco and the only lake in the Golden Gate National Recreation Area (see on map).

In 2001, the Presidio Trust, National Park Service, and Golden Gate National Parks Conservancy implemented a strategy to enhance the lake by removing sediment, restoring the landscape, and adding trails and benches.

But those plans were put on hold in 2002 when tests of the sediment revealed elevated levels of lead and motor oil from decades of highway run-off and urbanization.

Though the contaminants did not pose a risk to human health, they threatened the aquatic habitat. “Enhancement” of the lake turned to “remediation”. 

A major dredging of Mountain Lake is now underway.

The Presidio Trust is removing the contaminated sediment via pipeline to a staging area where it will be dewatered. The clean water will be returned to the lake, and the dried sediment will be disposed of offsite. Non-native turtles and fish are also being removed, and native wildlife will be re-introduced to the lake after it is dredged. In addition, run-off from Highway 1 will be diverted to prevent further contamination.

The Trust anticipates removal of more than 15,000 cubic yards of contaminated sediment. After dredging, the bottom of the lake will be graded to a stable and natural lake configuration, leaving a deeper, healthier habitat.

Like Las Lagunas de Anza, Mountain Lake has also become an open air classroom. This summer and fall, the Presidio Trust hosted monthly science talks on the lake’s shore.

As they were for Anza, these wetlands are again places to come discover and explore.


An Anza Trail wayside overlooks major habitat restoration underway at San Francisco's Mountain Lake
Credit: NPS

Las Lagunas de Anza
Credit: Don Clemans, all rights reserved

« Back to Blog Home