Water Quality Monitoring in the Presidio of San Francisco

Shoreline at Mountain Lake water quality monitoring site in the Presidio
Mountain Lake is one of several natural surface water features remaining in the Presidio, and one of the sites where water quality is monitored.

NPS / Jessica Weinberg McClosky

Map showing the location of freshwater resources and major roads within the Presidio

Why Is Water Quality Important?

Water quality is an indicator of the condition of aquatic habitat and is also an important indicator of the overall health of watersheds. Freshwater quality has a direct impact on marine water quality, riparian habitat, wetlands, and aquatic macroinvertebrates. It also impacts threatened and endangered amphibians, reptiles, and fish that depend on these habitats, as well as human recreation and enjoyment.
Water quality technician wades through deep stream while conducting water quality monitoring at Mountain Lake
Water quality technician collecting samples in Mountain Lake.

San Francisco Chronicle / Lea Suzuki

Why Do We Monitor Water Quality in the Presidio?

Although a history of Army use and urbanization has altered many of the natural features of the Presidio of San Francisco, several water bodies remain. These include Mountain Lake and Lobos Creek in the southwest portion of the Presidio, Dragonfly Creek in the northwest, and Tennessee Hollow in the east. In partnership with the Presidio Trust, National Park Service Inventory and Monitoring Program staff conduct monthly water quality monitoring at 16 sites in the Presidio to determine long-term trends in water quality parameters. These include water temperature, pH, dissolved oxygen, nitrate (as nitrogen), phosphate, and coliform bacteria.

How Do We Use the Monitoring Data?

  • To determine the extent to which lakes and streams at the Presidio meet federal and state water quality standards for recreation
  • To guide and evaluate projects to improve water resources, such as the ongoing Mountain Lake restoration efforts
Water quality equipment at monitoring site in Tennessee Hollow’s east tributary.
Water quality monitoring site in Tennessee Hollow’s east tributary.

NPS / Angela Pincetich

What Have We Learned?

Five years of monitoring has shown that water quality can vary greatly from month to month and site to site in the Presidio’s urban environment. Coliform bacteria and dissolved oxygen are especially variable, and can respond quickly with precipitation or seasonal drought. In the future, we anticipate that consistent water quality monitoring will allow us to evaluate long-term trends, as well as learn about the effects of active remediation and ecological restoration projects at the Presidio.

For More Information:

NPS I&M Water Quality Technician
Angela Pincetich

San Francisco Bay Area Inventory & Monitoring Network
Pacific Coast Science & Learning Center
The Presidio Trust

Summary by Angela Pincetich, March 2014.
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Last updated: May 7, 2018