Sleuthing for Sonoma Valley’s oldest streams

Today Arthur Dawson and I are sleuthing for old streams. We’re doing historical hydrology, really, constructing a map of natural streams in Sonoma Valley prior to the arrival of Europeans in the 1800s.

Settlers changed the landscape with shovel, pick and plow; in doing so, they unsettled long-established creek patterns that, today, remain mysteries. Hence the investigating, or field-checking, as our work is called.

We drive north-to-south through Sonoma Valley, stopping at a handful of select locations. Working with Alex Young of the Sonoma Ecology Center, Arthur has combed both historical and modern sources: early maps of Spanish ranchos, written records, topographic maps, aerial photographs and LIDAR (Light Detection and Ranging, or remote sensing). Now we’re matching the story each of the sources tells to our own gestalt of the valley. We know this place. We’ve been studying it for a few decades now.

We stop to field-check in the most unremarkable places. On the shoulders of roads. Beside the gentlest rises in elevation. At culverts that are barely noticeable in passing. Some locations don’t show obvious signs of water having run here: the ditching and draining that came with settlement altered the very course of water. So we have to find subtle bits of evidence. We look for stream cobbles long ago moved out of their ancient creekbeds (“reworked”) by gravity and erosion. We find water-loving trees left high and dry after streams were rerouted to neighboring parcels. We ponder the significance of tree roots dangling from high banks that once bordered a long-gone creek.

As we work, Arthur describes another job he’s finishing, one that characterizes the history of a winery property. The patriarch of a family of grape growers is 94 this year. He’s eager to have the history of the land completed soon. He’s also shared his philosophy of terroir as an experience, not just a product of the physical factors of soil, topography and climate typically ascribed to it. It’s a concept that combines art and science. Living well in place matters, he has said, the act of stewarding it and giving it your heart and soul.

Reconstructing the historical valley is a mix of art and science, too. Years ago, when Arthur and I first proposed this work for the Sonoma County Water Agency, we described its importance in understanding how surface and groundwater should be managed today.

Knowing the valley’s natural waterscape is one of the many roads the agency is taking toward understanding how underground water storage can best be done, say, or restoration projects should proceed.

Arthur and I continue our work into the afternoon. In the Temelec neighborhood, an old mansion built by Bear Flag Rebellion member Granville Swift still stands. It was, according to the California State Parks Office of Historic Preservation, built in 1858 “using stone quarried here by native Indian labor.” Arthur says the laborers were brutally enslaved for the work and Swift’s terroir would somehow reflect it (in 1875 the pioneer fell to his death from a mule outside the Berryessa Valley).

Today the Swift home looks docile, with mallards swimming on the estate pond and neighbors walking past with their dogs. Its peaceful feel masks its history, as some of the original geographies we’re seeking can no longer be seen on the ground.

We end the day remarking on our changing valley and how much our community has altered in the few decades we’ve lived here. We recall friends who’ve passed on or moved away, how demographics have shifted, how neighborhoods have changed.

Like death and taxes, we know, change is inevitable; we also know from experience that it shows up in the land and waterscape.

With time, though - maybe not geologic eons, but certainly historical decades and centuries - transformation finds its way into the home terroir. You can taste it.

Rebecca Lawton is a Sonoma-based author and scientist.