The Once and Future Delta

Mending the Broken Heart of California

by on April 01, 2010

 

View west over a range of north Delta habitats: wetlands on Prospect Island, the Sacramento Deep Water Ship Channel, and the open water of southern Liberty Island. Cache Slough, Yolo Basin farm fields, and the Coast Range are in the background.

Photo by Dale Kolke, CA Dept of Water Resources.

 

 

 

On March 30, 1772, Spanish explorer Pedro Fages was traveling east along the south shore of Suisun Bay, looking for a land route around the seemingly endless chain of bays extending inland from the Golden Gate. Mounting to Willow Pass, the rise of land between present-day Concord and Pittsburg, he found himself staring at a new obstacle: an enormous expanse of marshland, threaded with bright channels. He had “discovered” the Sacramento-San Joaquin River Delta.

The Delta is a flat, watery region of roughly a thousand square miles–covering nearly as much territory as San Francisco Bay, San Pablo Bay, Carquinez Strait, and Suisun Bay combined–radiating inland to the Central Valley. Its natural boundaries are fuzzy and its nature double. In one aspect it is a river delta; in the other it is the innermost region of that vast intrusion of tidewater into the continent called the San Francisco Estuary. (An estuary is a tidally influenced aquatic system with a range of salinities; this one is the largest on the west coast of the Americas.)

However defined, the Delta is the meeting point of rivers that drain 40 percent of California’s landmass and carry just under half of the runoff from California’s mountains. It is a crossroads on migratory routes extending in the air from the arctic to the tropics, and in the water from the Sierra out into the Pacific. It is also a rich-soiled farm region and, directly or indirectly, the source of drinking and farming water for the majority of the state. And it is, as the whole state now knows, in several kinds of trouble.

The Aboriginal Delta

Understanding what the Delta was and how it got into so much trouble is the starting point for envisioning a better future for it.

A delta is what forms when a stream approaches flat water. As currents slow, sediment settles out and the channel divides fanwise into what are called distributaries. The classic delta–think of the Nile–adjoins a coastline. It is a triangle, narrow upstream where the parent river enters, wide downstream where channels spill into the receiving water through several separate mouths. California’s great delta, by contrast, lies well inland, and it is backward or “inverted.” It is wide on the east because it is the creation of two different river systems, one flowing in from the north and one from the south: two deltas, really, not one. It is narrow downstream because all its branching channels must finally reunite at the inner edge of Suisun Bay to pass through the hills of the inner Coast Range.

North Delta scene, pre-1800
Early spring scene along the Sacramento River, with a Plains Miwok village on the bank and a condor overhead. The natural levees of the north Delta were covered with a thick gallery forest of valley oaks, cottonwoods, and willows, with “backswamps” and large ponds behind, all supporting large numbers of waterfowl and wading birds. Original artwork by Laura Cunningham, 2010.

The original Delta has been called “a tule swamp the size of Rhode Island,” a thumbnail that says more about our lack of knowledge than it does about the place itself. “We know surprisingly little about the ecological conditions that once characterized the system,” says Alison Whipple of the San Francisco Estuary Institute, which is in the midst of a research effort to derive a better picture. “The Delta is so unusual and was transformed so early. It’s complicated to fit all the pieces together retrospectively.”

But we do know that the building blocks of the Delta were its waterways, its natural levees, and its marshes, tidal and nontidal. The major channels were laid out then much as they are today. The Sacramento entered from the north, the San Joaquin from the south, the smaller Mokelumne River from the east, all throwing off distributaries but forced by topography to gather them in again downstream.

Alongside major waterways rose the levees, berms of sediment deposited over hundreds or thousands of years. In the north of the Delta, along the Sacramento and its branches, these stood 20 feet or more above the water and supported “gallery forests” of cottonwoods, sycamores, alders, and oaks, footed with brush and intertwined with vines. Along the San Joaquin and its branches, the levees were lower and more sparsely wooded. Downstream toward the heart of the Delta, and on smaller channels, the levees were low berms with willows on top, or no trees at all.

Behind these barriers, connected to the rivers by narrower channels, were the vast marshes, or “backswamps,” of cattails, reeds, bulrushes (tules), and other freshwater wetland plants. In the heart of the Delta these were tidal, irrigated twice daily through an intricate system of sloughs that branched and branched like tree roots. On the landward margins of the Delta, the tidal marshes graded almost imperceptibly into seasonal wetlands, flooded in the wet season only; and these into wildflower meadows, vernal pools, and oak savannas on the upland rim.

South Delta scene, pre-1800
Scene from the south Delta, along the San Joaquin River, shows braided channels, grasslands, and tule marshes, supporting populations of tule elk, sandhill cranes, white-faced ibises, white pelicans, and numerous ducks and geese. Original artwork by Laura Cunningham, 2010.

There were also many lakes and ponds, apparently larger in the northern part, that filled when river flows were high. And there were sandy hillocks, mostly at the western end of the region, near Antioch, that rose above the marsh, some supporting island groves of trees.

We say “The Sacramento-San Joaquin Delta,” and the hyphen has meaning. In the original landscape the two components were quite distinct. A Miwok Indian in a tule boat could have found only two narrow side-channels linking the major rivers before these finally merged at Sherman Island (see map). The Sacramento River brought in almost three quarters of the Delta’s water and waterborne sediments. Massive natural levees tended to confine its channels.

The San Joaquin River carried less water and sediment, which meant smaller levees and less impediment to branching. Entering the region at its southeast tip, the stream threw off a series of distributary channels to the west, picked up the inflow of the Mokelumne from the northeast, and made a great slow loop westward to its junction with the Sacramento. Around its lower channels extended the true sea of tules: an unbroken, rustling expanse of stalks, green or brown according to the season.

Though much remains to be learned about this aboriginal Delta, it is clear that it was a key organ in the ecological body of early California. Pioneer accounts tell us of abundances beyond the modern imagination: skies darkening with migratory birds, waters clogged with sturgeon and salmon. Such accounts arose again and again as Europeans plundered their way across America, but even among aboriginal landscapes the Bay-Delta system would have been extraordinary. In terms of the rate at which it creates living mass, freshwater marsh is one of the most productive kinds of vegetation in the world. Pouring bits of itself into the waters, it directly or indirectly nourishes animals from zooplankton to marsh wrens to salmon to (in the old Delta) grizzly bears. “The food supplies must have been just amazing,” says UC Davis fisheries biologist Peter Moyle.

The waters teemed with fish. Some, like the Delta smelt, lived entirely within this region. Many more species spent time there. Chinook salmon of the Central Valley passed through the Delta twice: once as immature smolts, pausing to grow and feed in Delta channels and floodplains on their way downstream to the sea; and once as massive adults, returning to mountain spawning grounds to breed and die. While many perished along the way, two million salmon returned in four distinct pulses, timed in fall, late fall, winter, and spring. Green and white sturgeon, Pacific lamprey, steelhead trout, and Sacramento perch made similar journeys.

This kind of diversity does not arise in a static or monolithic ecosystem. The aboriginal Delta was not one kind of habitat but many, closely intertwined: channels where the tides moved quickly, sloughs with placid waters, seasonal lakes, shallows and deeps, wetlands and uplands. It was also a place of constant change. Then as now there was a spectrum between fresh water at the river inflows and salt water at the Golden Gate, a gamut that shifts with every tide and every season, and in longer cycles as well. Floods could turn the entire region into a lake. Droughts longer and deeper than anything we have experienced brought salt deep into the Delta, though scientists debate how often. The native minnows of the region differ from their relatives elsewhere in that they can tolerate quite saline water. This was a system adapted to wide swings.

Wintering cranes
Wintering sandhill cranes forage in fallow Delta farm fields. Photo by John W. Wall, jwallphoto.blogspot.com.

At the time of European contact the Yokuts, Plains Miwok, and Bay Miwok peoples lived around and in the Delta, wherever levees provided higher ground, catching fish as well as hunting and gathering from the land. Here as elsewhere they used tule products for food, clothing, dwellings, and boats; they burned the marshes to flush game. As the Spanish mission system drew the natives into its grip, the soggy region became a refuge for those who did not care to “convert” or who escaped to resume the old life. Epidemics in the 1830s devastated these encampments, leaving the Delta perhaps emptier of people than it had ever been. Then came the discovery of gold just outside the region.

In the 150 years since the Gold Rush, the natural delta has been changed beyond recognition. Its physical layout has changed, the movement of waters through it has changed, and its plants and animals have changed. It now appears to be on the verge of a further transformation.

Reclamation

With the discovery of gold, the Delta was suddenly the vital corridor between San Francisco and the mining districts in the Sierra Nevada. The forty-niners passed through it along the major rivers, in steamboats and craft of all sorts, learning by experience which channels were thoroughfares; the surrounding tracts of marsh remained untouched, rather like wilderness on either side of a superhighway.

Soon, however, land-hungry settlers gained a foothold on the same natural levees the tribes had occupied. Then they turned their attention to the adjoining “backswamps,” where a kind of underwater gold awaited them: the fertile peat soils formed by millennia of decaying tules.

The diking of the Delta for farming–”reclamation”–got started wherever natural levees provided a foundation. It was a halting affair at first, with many setbacks. Then a new machine, the long-boom clamshell dredge, came to the rescue. These vast contraptions–the later ones had booms over 200 feet long–moved along the channels, scooping up bucketfuls of mineral river bottom sediment and dropping it along the margins of the land to be reclaimed. In several passes a dike would be formed and the soggy area behind could be drained and eventually farmed. Over time the initial zones of reclamation were solidified and expanded. The depths of the central Delta, where peat soils were least leavened with alluvial sediments, were the last to succumb.

By 1930, the process was complete. The area of the Delta subjected to tidal influence had been reduced from perhaps 400,000 acres to 40,000. The former marsh and floodplain had been transformed into a patchwork of some 70 diked enclosures called islands or tracts. Thousands of miles of channels had been eliminated, but the larger waterways had in many cases been deepened, widened, straightened, and extended: former dead ends had been punched through to make water links that had not existed before. The resulting network was not so much a delta as a unified, though intricately patterned, tidal basin.

Ship passing above farmland
Here along the Sacramento Deep Water Ship Channel (at Z Line and Hamilton roads), as in much of the Delta, the water level is higher than the surrounding land, which is protected by levees. Photo by Jeff Myers, tommyersphotography.com.

People noticed from the earliest days that the new-made land behind the levees was sinking below the level of the lowest tide. Only in the 1920s was it understood why. The soil surface subsided partly because of compression, but chiefly because the plant matter in it, accumulated during centuries underwater, oxidized when exposed to air and sunlight. It didn’t help matters that farmers literally set fire to the combustible ground, first to prepare it for agriculture and later to free up nutrients for crops, a practice that continued until about 1950.

Year by year the surfaces of the peat islands sank, creating what have been called “holes surrounded by dikes.” On about 20 islands, some land now lies 15 feet below sea level, or more. On the margins of the Delta, where the peat was shallowest, it is used up and subsidence has ended. On most of the deeply subsided tracts, however, there are fathoms of peat still to be lost.

Passing in a ship between such tracts, looking down at the top twigs of pear trees or the tassels on rows of corn, you feel an eeriness, a reversal of nature; you wonder how long this can last. With every foot of subsidence inside a levee, the relative pressure from the water outside increases. Not much of the levee mileage in the Delta is built for such stresses. Levee breaks–spaced just far enough apart in time so that each comes as a shock–have punctuated modern Delta history. Most have been repaired, but a few tracts have been left to the water, notably Sherman Lake at the Delta’s western tip, Big Break near Antioch, and Franks Tract and Mildred Island in the central Delta.

broken levee aerial
Runoff from the warm storm in January 1997 caused this levee on the Cosumnes River to break, temporarily re-creating the floodplains that were a regular feature of the aboriginal Delta. Photo by Tom Myers, tommyersphotography.com.

The most recent break happened in 2004, when a levee on the Middle River northeast of Stockton gave way. Within a week 12,000 acres of adjoining Jones Tract were flooded. The break occurred under a clear sky. The tide was high, but water levels were not swollen further, as they often are, by high runoff from the mountains; in fact, 2004 was a rather dry year. Nor was Jones Tract considered an especially fragile island.

After the levees were repaired, two University of California scientists, Robert Twiss and Jeffrey Mount, decided to take a hard look at the Delta’s vulnerabilities. They considered past and future subsidence within the islands and the risks of floods and large earthquakes over time. They also made a first attempt to reckon with two new threats resulting from global warming: sea level rise and the probability of greater runoff peaks from winter storms. They concluded that a landscape-changing event was in the cards: the simultaneous inundation of numerous Delta islands. Recovery would be difficult and exceedingly expensive.

Six months after Mount and Twiss published their paper, Hurricane Katrina tested the New Orleans levee system, much more massive than the California version, and found it wanting. The unthinkable (though quite predictable) had happened. It dawned on more and more observers of the Delta scene that it could happen here.

Flows

Even as reclamation was nearing completion, a second transformation was under way: the weakening and redirection of river flows. Riverbank farms along hundreds of miles of streams tributary to the Delta were drawing on them for irrigation. At the same time, coastal cities were sending aqueducts past and even through the region to divert mountain streams in the watershed. In 1929, the East Bay Municipal Utilities District tapped the Mokelumne; in 1934, San Franciscans began drinking water from the Tuolumne–all at the cost of Delta inflows. It was a manmade drought that, unlike the periodic natural ones, would only intensify.

Delta pumping plant
In 2009, 3.5 million acre-feet of water were pumped from the Delta to San Joaquin Valley farms and urban users in the Bay Area and Southern California. The draw of the pumps, including the State Water Project’s Harvey Banks Pumping Plant near Tracy, is powerful enough to trap fish and alter the currents through the Delta. Photo courtesy CA Dept of Water Resources.

The engineers were at work on something still more ambitious: a plan to shift water from the Sacramento Valley to the arid but fertile San Joaquin Valley, using the Delta itself as part of the plumbing. Huge dams on the Sacramento and its tributaries would capture winter floods and gradually release them in summer and fall. At the southwest edge of the Delta, near the town of Tracy, enormous pumps would lift an equivalent amount of water out of the channel called the Old River and send it southward to the farm belt. The state and federal governments both sought to execute this concept and, in the end, built parallel versions. The federal Central Valley Project finished Shasta Dam in 1945 and started pumping at Tracy in 1951 through the Delta-Mendota Canal, serving both Central Valley farms and several Bay Area water districts. By 1968, the state had chimed in with its State Water Project, similar except for its longer reach: The California Aqueduct delivers water to the urban areas of southern California as well.

In 1951, 220,000 acre-feet of water went south from the Delta. (The acre-foot, enough to cover one acre one foot deep, is the basic coin of the water economy.) In 1985, the total of both projects passed five million acre-feet, approximately the volume of San Francisco Bay. In 2000, the six-million acre-foot mark was reached. Combined with other withdrawals from the Delta watershed, this pumping reduced the outflow from the Delta by something between one quarter and two thirds, depending mainly on the wetness of the year.

The draw of the pumps is so huge that it essentially gives the Delta a second, southern mouth. Currents flow toward it, altering and sometimes even reversing their natural direction. Millions of fish follow the treacherous cues, dying in the waterworks. “They think we’re the Bay,” a federal biologist says ruefully.

The timing of flows has also been changed. The old Delta experienced a glut of water in winter, a sustained spring pulse of moderate flows as snows melted, and a seasonal drought in late summer and fall. Since the water projects hit their stride, dam-constrained winter flows have lessened somewhat and spring flows greatly, while those of late season have become much stronger as dams release water for farms and cities. Except in years of epochal flooding, the wide swings of nature have been damped down.

Several things threaten the continued functioning of this system. The first is sea level rise and the slow encroachment of salinity that is predicted to come with it, even if all levees hold. The second is the risk of multiple island flooding, which could bring unusably salty water to the pumps far sooner and far faster. And the third is the decline of native Delta fish, now become so dire that it has triggered protective laws that in turn have halted–and could reverse–the rising export trend.

Habitat

Geese at sunset
A V-line of geese crosses the winter sky at sunset above a tule marsh near the western end of Woodbridge Road on Bract Tract in the north Delta. Photo by Rich Turner, turnerphoto.com.

Travel the Delta at the right place and time–say on a boat around Venice Island on a February day–and you can’t be unmoved by the living world around you. Snow geese and tundra swans rise by the thousand from a rain-soaked field; sandhill cranes lift their larger, more ragged forms. A beaver looks across from its dam among fringing tules. A river otter dives and reappears. There is even a sea lion, basking on a buoy.

Yet as a living space for creatures, the modern Delta is both changed from what it was and on balance greatly diminished. Though all families were affected, the native fishes have paid the highest price.

Even before the heyday of reclamation, two species had been lost (to the effects of hydraulic mining upstream): the abundant and tasty thicktail chub and the Sacramento perch, a valued game fish. After reclamation, there was simply less room for fish. The destruction of marshes, slough systems, and floodplains removed most of the rearing and refuge habitat for salmon and other species and also reduced the flow of nutrients into the streams.

At the same time a steady influx of fishes and other organisms not native to the Delta–some brought here deliberately, some not–was reweaving the web of life in Delta channels. Among the first introductions, in 1879, were two eastern game fish, striped bass and American shad; the stripers still support a major sport fishery. The procession continued: black bass, largemouth bass, catfish, carp (planted on purpose though now despised), bluegill sunfish, shimofuro goby. Today, of 50 species of fish in the Delta, over half, including the most successful, are exotic.

The more significant divide, biologists say, is not exactly between exotic and native. It is between those fish, indigenous or not, that flourish in the changeable conditions of an estuary, and those–like carp, catfish, and the various sunfish–that prefer calmer, warmer, and clearer waters, often among beds of aquatic vegetation. Over time, and especially since the 1960s, the latter group has steadily gained on the former.

Invaders of other sorts helped this transition along. On the channel bottoms, native mussels were replaced by two species of clams from Asia, very efficient filter feeders that further cleared the water. Then there was the water hyacinth, an ornamental species from South America. Escaped to the wild, it took hold in quieter Delta waters, notably on flooded islands, and completed their conversion to sunfish farms. Hyacinth would later be joined as an ecosystem engineer by the Brazilian waterweed Egeria, found in a million goldfish bowls and now all over the Delta as well.

The decline of the estuarine fish species was no straight-line affair; like a bear market in stocks, the biological bear market of the late 20th century had its anomalies and momentary rallies. Things got better in wet years and worse in dry ones. Some species bucked the trend for a while. The commercially valuable fall salmon run, propped up by hatchery releases, rebounded remarkably, for a time. In retrospect, however, the downward slide has been inexorable. Six native fishes–the green sturgeon, the longfin smelt, the Delta smelt, the winter-run chinook, the spring-run chinook, and the Central Valley steelhead–are now listed as endangered or threatened by the state or federal government.

After 2000, the biological retreat became a rout. Scientists coined the term “pelagic organism decline” to cover the simultaneous fading of open water species from smelt to stripers to threadfin shad, joined later by the previously numerous fall-run salmon. The little Delta smelt, on the edge of extinction, became exhibit A for those who wanted to protect the Delta’s native fish–and for those, especially southward along the aqueducts, who mocked and resented such concern.

By 2004, scientists concluded that what was happening was more than an accumulation of problems. It was a change of state, a “regime shift.” The Delta waters had reached a tipping point at which they simply could no longer support the fish that had historically prospered there, and there was no sign of a tipping back. With its steady and managed flows, its clearer and warmer waters, and its spreading mats of plants escaped from fishbowls and ornamental pools, the Delta was less and less an estuary, complex and changeable. Bill Bennett of UC Davis compares it to “a lake in southern Arkansas, naturally full of species that thrive in lakes in southern Arkansas.”

In a system as complex as this one there is always room to argue about cause and effect. Yet there is no escaping the parallel between the downward progress of many fish and the upward progress of water exports via the pumps at Tracy. In 2005, environmentalists sued in an attempt to dial back those exports, hinging their case on the plight of the smelt and the salmon. In 2007, Judge Oliver Wanger of the federal District Court in Fresno indeed applied some modest limits to pumping. His decision signaled that continued water exports were contingent on bringing this fish–and by extension the whole estuarine ecosystem–back from the brink.

The Delta in Crisis

Feeding frenzy, and earth mover...
Some birds flourish in the human-altered landscapes of the Delta. Here American white pelicans and great egrets swarm a reopened irrigation ditch on Jones Tract. Photo by Rich Turner, turnerphoto.com.

Anguished talk about the Delta, and promises to make it better, have been with us for decades. The Jones Tract break of 2004 and the Wanger decision of 2007 were the two shocks that would lead, this time, to more decisive action.

In November 2009, the state legislature created a Delta Stewardship Council to tackle the region’s problems head-on and offer an overarching Delta Plan on January 1, 2012. It also set up a Delta Conservancy to buy land for habitat projects and strengthened the Delta Protection Commission, which controls development on the lower-lying islands. The lawmakers instructed the State Water Resources Control Board to wrestle once more with the much-studied, much-evaded question of exactly what flows should be permitted to pass through the Delta to the Bay. California voters, for their part, will be asked in November 2010 to approve a huge water bond issue, including (among many other items, some of them controversial) $2.25 billion for habitat work in the Delta.

All of this effort is supposed to serve two competing goals, which the Legislature has now mandated as “coequal”: to “protect, restore, and enhance” the Delta ecosystem, and to provide for “more reliable” water exports. Critical to each objective is the question of the levees and what the physical Delta will look like 50 or 100 years from now.

Scenarios for the Future

For orientation, let’s start with two improbable scenarios. At one end of the spectrum is a future in which everything is done to keep the Delta in its current configuration, with almost every levee, every island intact. This is the future that most Delta residents and farmers wish to see. Engineers agree that it could physically be done. “We could have a little Holland out there,” says Bruce Herbold of the Environmental Protection Agency. But it’s a matter of expense, in the many billions of dollars, and by whom it would be borne. Realistically, Holland West is not an option. And it would do nothing good for the fish.

At the other extreme is a future in which levees are let go on a grand scale and nature is allowed to take its course. The likely result would be an inland sea 20 miles wide from east to west and 40 miles long from north to south, covering about half of today’s Delta. Stockton, already a seaport, would be a coastal town as well. This vision, or nightmare as many would call it, has no advocates, though it could conceivably come to pass.

What the planners will actually have before them is a range of middling options in which the existing texture of the Delta will be reinforced in many places, especially on the less subsided lands, but profoundly altered in others, and in one of several ways.

Marshes

Biologists pin much of their hope for ecosystem recovery on the establishment of marshes linked to tidal channels, limited echoes of the old Delta harmony. The Bay Delta Conservation Plan, an official state effort funded by water agencies, calls for at least 13,000 acres of such marshes, sited near the sea level line, especially in the South Delta and in the northwestern quadrant.

Floodplains and channel margins

The typical Delta channel now is a rock-lined ditch. The Conservation Plan calls for softening some 20 miles of shores. It would also find room for at least 15,000 acres of floodplains and riparian forests. Study after study shows how important such seasonally overflowed lands are to salmon and other fish. Biologists think expanded marshes will be good for fish and wildlife; but when it comes to floodplains, they know.

Subsidence reversal farming

The marsh plants that made the old Delta soils can also make new ones. Work done on test plots has raised hopes that managed tule wetlands could rebuild the vanished peat at the rate of a foot per decade or more. A more traditional crop, rice, may also have some ability to raise the soil surface.

Open water

Here is the most controversial idea on the table: to deliberately concede some or many deeply subsided islands to the tide. This strategy, probed in a series of studies by the Public Policy Institute of California, accepts as inevitable and possibly desirable the formation of a sizable area of open water in the western and central Delta. It might be about the size of San Pablo Bay.

Geese at sunset
A V-line of geese crosses the winter sky at sunset above a tule marsh near the western end of Woodbridge Road on Bract Tract in the north Delta. Photo by Rich Turner, turnerphoto.com.

To say the least, Delta residents, and not only farmers on the targeted islands, oppose this plan, and they have practical difficulties to cite. Wind-driven waves on the new expanse would menace surviving adjacent levees. The open water would be somewhat saltier, interfering with irrigation from local channels. In the words of one critic, “a big, expensive mess.”

A very few years ago, biologists would have joined in decrying the flooding of multiple islands. Existing drowned islands, notably Franks Tract, had turned into monocultures of invasive plants, useless for the fish species of concern. Recent experience has caused some rethinking. It appears that what happens to an inundated island depends on the liveliness of its currents and the depth of its water. They do not all become sunfish ponds. And salinity increases would in theory favor the estuarine fish, which could take them in stride, over the reservoir fish, which could not.

Though opinion is sharply divided, an influential cohort of Delta specialists now sees such an inland bay as the key to a better Delta, not a threat to it.

Water exports

And what of the future of big water diversions? Even without island failures, rising sea level will inevitably bring salt water closer and closer to the intakes. Eventually, if exports are to continue, the water will have to be taken from the Sacramento above the Delta in an “isolated conveyance” (aka, the Peripheral Canal). Voters rejected an earlier plan for such a canal in 1982; recent studies endorse it, though some variants would keep the old route through the Delta open too (“dual conveyance”).

Environmental groups, once uniformly opposed to such an “isolated conveyance,” are now divided or conflicted. The present system is messy and destructive; a more elegant one that took more water would be worse. “It’s not really a question of the plumbing,” says Tina Swanson of the Bay Institute. “The real issue is how river flows and freshwater flow to the estuary are managed.” How much diversion can there be if the ecosystem protection goal, now spelled out in law, is to be met? Multiple lines of evidence suggest the answer: much less than there is now.

Which Way for the Delta?

10-328-Turner-Levee Look Out.jpg
A winter storm looms over Twitchell Island, seen here across Sevenmile Slough from a levee road on Andrus Island. Photo by Rich Turner, turnerphoto.com.

At a recent hearing, a resident complained: “You are deconstructing the Delta as Delta people know it.” But human memories are short. The history of the modern Delta belies the image of the region as a static landscape. Reclamation was a battle with many setbacks, almost given up for lost in the 1870s. In the 1880s the “crisis” was the clogging of channels by hydraulic mining debris. In the 1920s, salinity was on the march. A brief calm at midcentury gave way to the ever-spiraling tension over water exports and ecosystem decline. The Delta seems always to have been in crisis, under intensive study, and at the intersection of hostile interests.

The Sacramento-San Joaquin River Delta is not going to disappear under the waves. Even if some fields become marshes, streamside forests, or open waters, the essence of the region–a honeycomb of farmlands and waters patterned by dikes–will probably be unchanged for centuries to come. But with luck–and political will, and good science, and a lot of money–the Delta might also become again what it has not been for decades: a functioning, changeful part of the greatest estuary on the Pacific coast of the Americas.

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