The delta of the Sacramento and San Joaquin Rivers covers over 1000 square miles of north-central California. The city of Sacramento lies at the delta’s northern apex, Stockton and Tracy are the two biggest cities at its southern end, and to the west the delta’s water flows into Suisun Bay, near the towns of Pittsburg and Antioch. From there it continues into San Pablo Bay, San Francisco Bay, and the Pacific Ocean.
(The map will come up with a marker on the town of Rio Vista, roughly in the center of the Delta region. To its left you’ll see Suisun Bay. By zooming in on the area between Rio Vista and Suisun Bay you can locate Grizzly Island and Collinsville, where some of the following photos were taken.)
The Delta was settled by white people in the mid-19th century; what had been marsh was drained to form a vast, flat landscape of agricultural land cut through by mostly man-made channels known as sloughs, contained within over a thousand miles of levees. When dry, the peat soil of the Delta is combustible. Signs by the side of the highway warn you not to build campfires. Originally it was so marshy that horses and wheeled vehicles sank into it; the caterpillar tractor was invented for the purpose of working the land of the Delta. Once it was drained and cultivated, the soil began to subside so that today the land of the so-called Delta “islands” is lower — in some places twenty feet lower — than the water that flows past them, held back by levees.
The Delta is the key to California’s water supply; about half of all the water flowing down California’s streams and rivers ends up in the Delta, and 25 or 30 million people depend on this source for at least some of their drinking water. A significant fraction of Delta water is sent elsewhere for drinking and irrigation, especially to the south, through the State Water Project and the federal Central Valley Project. This might be all well and good except that it doesn’t leave enough water behind to take care of the needs of the Delta itself.
California is in a dilemma: the Delta can’t afford to give up all the water it is exporting, and those who are getting it now can’t afford to give it up either. Meanwhile the population continues to grow.
Last April, a California judge ordered the pumps that send water to the south turned off because low water levels were threatening the delta smelt, an endangered species, thought to be an indicator of the whole ecosystem’s health. This shutoff caused, to say the least, consternation on the receiving end of the aqueduct, and after ten days the pumps went back on. That didn’t mean the problem was solved. Environmentalists say that the Delta’s ecosystem is slowly dying. Most of the Delta isn’t truly a wetland; instead it consists of agricultural fields of compacted soil separated by sloughs and canals. The diversion of fresh water to the south, and all of the other human engineering of water in the Delta, has caused the brackish zone at the interface of fresh and salt water to be transformed. Many species of fish native to the Delta are in long-term population decline. Invasive plants and fish have displaced native species in many areas. The quality of Delta water is degraded by intrusion of sea water, agricultural chemicals, runoff from urban areas, the salinity of water draining from irrigated fields. The Delta’s earthen levees are fragile and vulnerable to failure, especially as the land they’re protecting subsides more and more. If a major earthquake were to occur there, which is hardly a far-fetched scenario, levee breaks and catastrophic flooding would be the result.
And yet the Delta harbors a great deal of beauty, and you would never know, just by looking at it, that the story unfolding here is about a shortage of water.
On March 13-14, Vaughn and I made a side trip to the Delta for a couple of days while in the Bay Area visiting her sons. Our first stop was at Suisun Marsh, which is the largest estuarine marsh in the United States.
It was cloudy, with intermittent sprinkles of rain.
We drove into the Grizzly Island Wildlife Area, where we encountered only a couple of other cars on miles of levee roads. The weather cleared. This is Howard Slough:
and this is known as Steve’s Ditch:
Water was draining into it from an adjacent field, or pond; parts of the area are flooded and drained on an annual cycle.
Next day, more driving on levee roads, flat and mostly straight, bristling with signs warning against drunk driving, telling drivers to put on their headlights, safety zone, drive to survive.
The land is visibly lower than the water beside it, in many places.
We took a road east of Montezuma Slough, south through the town of Bird’s Landing, down to Collinsville on the Sacramento River.
This project is described on a sign as “tidal restoration.”
The flow of freshwater through the Delta interacts in the rivers and bays with the tidal flow coming up from the Pacific. At one time, before the Delta was so thoroughly human-engineered, the salinity in this boundary zone fluctuated more than it has been allowed to under our management, and some believe the ecosystem as a whole would benefit if that natural variability were restored. Whether this project has anything to do with that idea, I never found out.
The Sacramento River at Collinsville:
The Delta is a land of prevailing west wind with little or nothing to slow it down.
Our last stop was at Clifton Court Forebay, the reservoir that collects water from the Delta, near Tracy, before it drains into the California Aqueduct — a place that cannot be called nature.
This is the place where water leaves the Delta on its journey to the south.