Deltas, I always thought, were river sediments deposited in oceans that pushed the continental shore out into the sea. Picture the Mississippi Delta extending into the Gulf of Mexico. The California Delta (more accurately, the Sacramento–San Joaquin Delta) is different – it’s actually inland of the Pacific Ocean. Picture moving eastward from the Pacific, past San Francisco and the San Francisco Bay, through a strait and then finally into the Delta itself. I was informed that the aquatic part of this system comprises the San Francisco estuary, the largest estuary on the Pacific side of the Americas.
The California Delta covers some 1153 square miles. It’s shaped like a triangle with a long side running from Sacramento in the north to a point 70 miles south with a westward vertex pointing to San Francisco Bay.
Eons ago, the delta was open water. I picture it as a sort of inland sea that had an outlet to the ocean. The inland sea was fed from the north by the Sacramento River and from the south by the San Joaquin. Over time, river sediments partially filled the sea. Wetland plants colonized those sediments, with the result that the Delta had the nature of a large marsh with little dry ground, and with twisty and braided riverways. Tidal effects, as they still are today, moved a saltwater-freshwater interface landward and seaward. These circumstances set up an environment for abundant and diverse aquatic life, as well as animals that live on the land-water interface such as waterfowl and other birds.
Fast forward to the ’49 gold rush and settlement, and the rest is history. Winding riverways were an impediment to boat traffic, so channels were dug and straightened. The Swamp Act gave land to anyone who would drain it and make it productive, and so entrepreneurs ditched, drained, and leveed the marshes leaving the pattern of “islands” seen today. These islands are almost entirely agricultural, surrounded by levees to keep water out.
An aside here for just a second. As a Wisconsin guy, I’m used to seeing a levee here and a levee there. Levees are everywhere in this river and delta system! Starting above Sacramento into the delta and southward as far as we tracked the San Joaquin, there was zip – nada flood plain (and flood plain habitat), only levees.
But back to the Delta.
The Delta islands have now been farmed for 100-150 years. Some of the peat soils were burned off by fire, but a lot more over time by just rapid oxidation of the peat coming into contact with air. The “islands” and lots of other delta lands are now up to 15 feet below sea level. Instead of being wetlands that absorb flood pulses, these “reclaimed” lands need to be protected from floods which intensifies flooding elsewhere. The levees occasionally fail, flooding islands and requiring remediation at huge costs. My Department of Water Resources tour guide, Mike Miller, reported that a levee breach in 2004 cost $97 million in public dollars to fix. That comes to $7500 per acre of farmland, for land that will become inundated again from a future levee failure. A tacit acknowledgement seems to exist that some or all of the islands are ultimately doomed. A sound argument could be made to simply buy out owners of vulnerable land.
When it comes to aquatic challenges, the Delta suffers from almost the complete suite: water diversions, invasives (fish, plants, crabs, others), warming, rising sea level (the latter two are associated with climate change), no flood plain, saltwater intrusion, subsidence, water diversions, fish entrainment and mortality in pumping plants.
(I hope to explore the diversions in a future piece, but it’s too long to get into here.)
But people aren’t throwing in the towel. The feeling among government agencies, water advocacy groups, and scientists is that the Delta is too damn important to a critical list of critters. Though diminished in numbers and badly beaten-up, they have a fighting chance. Without a healthy Delta, forget restoring Sacramento–San Joaquin salmon runs.
Here’s a term I just learned when applied to fixing ecosystems: Reconciliation. Reconciliation is when it is recognized that the current ecosystem isn’t working well, but the whole system is too shot to do a restoration of natural conditions. So what can you do? Take what you have and make it functional. Restore habitat, control invasives where you can, but where you cannot, integrate them into new ecosystem. Restore flow regimes. Fix water quality.
I can picture a restored Delta. Here are a couple simple places to start: allow islands once flooded to stay flooded. Regrow wetlands on them for fish and fowl habitat. Manage diversions better. Fix water quality. It would take time and money, but ultimately it is do-able.