Topsoil and Our River
A recent coffee shop conversation included some words about the river. “It’s gotten clogged with silt ever since they put the flood control dams in. I remember when I couldn’t stand up anywhere along most the parts of Sewell because it was 9 feet deep.” You can say just about anything in coffee talk. But it got me thinking again about all the silt that has come down Sessom Creek as we constructed a village and a university. I drifted back farther still in time to the early 1800’s when we began to scratch, plow, graze or bull doze as much as we could of the San Marcos River watershed. It reminded me of a chapter opening on erosion control from a book first published in 1975 titled The Earth Manual: How to Work On Wild Land Without Taming It by Malcolm Margolin:
… A visitor from outer space might have a good laugh at how we handle – or don’t handle – erosion. Our homes have locks on the door, latches on the window, insurance policies in the dresser drawer, and we support a huge police and prison system – largely to protect a few cameras, watches and other gewgaws. Meanwhile, outside our windows, every rainstorm carries away thousands of tons of valuable topsoil upon which we depend for our very survival. Our scales of values are pathetically confused. With modern assembly-line methods, we could replace a stolen tape deck in minutes. Yet it takes nature almost a thousand years to rebuild one inch of topsoil.
I wonder how much of the already thin topsoil of our area has ended up downstream. Topsoil is key to supporting the vegetation, preferably grasses, that, with the soil, holds rain, prevents and even filters some runoff and allows it to soak in or find its way to open fissures leading to the aquifer.
I know, the question now is, will it ever rain again. Maybe one of these days we will truly understand the value of topsoil and manage the watershed with the respect of the valuable services it provides. Then, even if it doesn’t rain, perhaps the water in the river will be a little deeper and a little clearer even in a drought…t.o.d.