Chico, Sustainable

Instead, picture yourself at the beach, digging a hole in the sand near the water's edge. After digging down about a foot or so into the wet sand, the water from the wet sand starts to seep into the hole.

Now imagine that you somewhere in Chico, and your hole is, say, 600 feet deep. Similar to the wet sand, at this depth the rock, sand, soil etc. is saturated with water. This is groundwater. Just like the sand, when you dig a hole that deep, water will seep into it. This is a well.

The saturated area of underground substrate (a substrate can be rock, gravel, sand, silt, clay etc.) from which water can be extracted is called and aquifer. The aquifer beneath Chico (and beyond) is called the Tuscan Aquifer. It is named for the "Tuscan Formation," which are layers of deposits (rock, soil, sand) from ancient streams and volcanic mudflows. (I don't know who named it the "Tuscan," though perhaps there is a similar geological formation in the Tuscany area of Italy).

The Tuscan Aquifer is big, though it is hard to be precise regarding its size and shape. Imagine a massive blob of saturated substrate beneath Butte, Tehama, and Glenn Counties, extending to depths of over 1000 feet, containing an estimated 10 times the amount of water as the capacity of Lake Oroville.

How did it get into the ground?

Many aquifers around the world contain ancient water, water that perhaps fell as rain thousands of years ago, saturated the ground, and stayed there, like a coal or oil deposit. Other aquifers are continually "recharged" (yes, like adding juice to your cell phone battery) as surface water slowly seeps down from the surface into the aquifer. The recharge rate of an aquifer (if there is recharge) depends on the amount of surface water that is able to seep down combined with the geology of the region, as some substrates are more porous than others. For example, water will easily seep through sandy soils, while clay or bedrock may form an impermeable layer through which water cannot easily pass, if at all.

Geological providence has been very kind to our region, as the water-bearing Tuscan Formation is exposed to the surface in the foothills above Chico and Durham, and then slants downward beneath us. It can be hard to visualize, I know. But in a nutshell, water (from snow and rainfall) enters the aquifer in the foothills above, and then gravity pulls it downhill through the formation (yes, the water in our aquifer is slowly flowing underground towards the Sacramento River).

As a result, the Tuscan Aquifer is one of the cleanest, largest, and "healthiest" aquifers in the state, providing a stable water source not only for agricultural and municipal use, but also for plant and animal habitat. How? The Tuscan Aquifer is also key to the health of our year-round creeks such as Big Chico Creek and Butte Creek. Without the aquifer as a source, these waterways would dry up in the summer months.

It imperative that understand all of this, so that we can value this resource appropriately.

Thank you to Lynn Barris for contributing her wisdom to this post.