Water Resources Collections and Archives
Islais Creek reinterpreted: An exploration of restoration designs in the urbanized context of San Francisco
- Author(s): Griffith, Lucas A
- et al.
In my initial inquiry into the environmental history of the Alemany Farmers’ Market in San Francisco, I learnt of a creek – Islais Creek, the largest watershed in the city.
I measured and analyzed an 1869 U.S. Coast Survey to establish a representative baseline for the historical character of Islais Creek. Historically water accumulated on the shallow soils of the San Bruno Mountains and flowed into Islais Creek I used additional maps and surveys from the late nineteenth and early twentieth centuries to document the cultural settlement of the watershed and further discuss land use impacts on the creek. For the past one-hundred and fifty years urban expansion and development have severely altered the original character of the creek and disallowed natural fluvial dynamics to persist. Currently the creek serves as the infrastructural backbone to a combined sewer system located underground in concrete pipes and culverts.
In this repost I developed a restoration plan informed by an opportunities and constraints analysis of the existing conditions within the watershed. The plan gathers surface flows from a small subwatershed adjacent to the farmers’ market site and uses the historical baseline condition to inform creek design. I used the rational method to establish a design discharge and discharge from the 200 acre subwatershed area and employed other standard hydrologic and hydraulic methods to estimate appropriate channel geometry for a two year flow regime.
The restoration of Islais Creek as proposed in this report represents an exploration of thought more than classic geomorphologic restoration; the landscape tells the story of the creek and restores its symbolic presence in the urban environment and in the minds of the people living and visiting the space. The proposed creek form builds an understanding of the fluvial process, enhances our knowledge of aquatic ecosystems and ultimately enriches our connection to place. We are restoring more than ecological systems, we are restoring our awareness and compassion for nature.