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| ISBN-13: | 9780520952195 |
|---|---|
| Publisher: | University of California Press |
| Publication date: | 04/30/2012 |
| Series: | California Natural History Guides , #105 |
| Sold by: | Barnes & Noble |
| Format: | eBook |
| Pages: | 352 |
| File size: | 14 MB |
| Note: | This product may take a few minutes to download. |
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Field Guide to California Rivers
By Tim Palmer, William E. Avery
UNIVERSITY OF CALIFORNIA PRESS
Copyright © 2012 The Regents of the University of CaliforniaAll rights reserved.
ISBN: 978-0-520-95219-5
CHAPTER 1
THE NETWORK OF RIVERS
Most California rivers flow into the Pacific, but some flow into landlocked basins of the interior deserts. This field guide groups the rivers into six hydrologic regions. Each includes a specific basin (also called a watershed, which is all the land that drains into a river), or a collection of smaller but similar basins, such as the North Coast region.
Most water flows in just four rivers: the Sacramento, Klamath, Eel, and San Joaquin. The combined North Coast rivers along with the Sacramento and San Joaquin carry 90 percent of the state's total runoff. Most people and most farmlands lie south of Sacramento, and so the development of California's rivers has been a story of tapping these northern and Sierra Nevada rivers and diverting them south or to the coast.
California's Largest and Longest Rivers
The state's largest river in volume of flow is the Sacramento, followed by the Klamath and Colorado, though by the time the Colorado leaves the state it's diverted with little left in the channel. The longest river under one name is the 374-mile Sacramento, though substantial mileage is tidal in the delta and San Francisco Bay. The Pit, however, is the upper Sacramento's largest source, and when combined with the Sacramento River below its mouth, totals 540 miles. Similarly, though small in volume, the San Joaquin with its South Fork source totals 393 miles—longer than the Sacramento or Klamath. The table that follows lists the volume of the largest rivers plus the mileage of major rivers plus their key headwaters tributary—in effect the same stream under a separate name. For data methods, see the beginning of the river profiles.
North Coast Rivers
The North Coast region is soaked by winter rains, and rivers here account for 43 percent of California's runoff. They wind through conifer-clad mountains and green valleys that are fog-shrouded or sun-basked depending on the month of the year, and they carry powerful winter flows to sea-level estuaries or ocean beaches at the dramatic coastal escarpment that continues almost uninterrupted from San Francisco to Oregon. The Klamath is the largest waterway here, beginning in the interior mountains of Oregon and cutting an epic course across the southern Cascade, Klamath, and Coast ranges.
The other major river of the north is the Eel, with tributaries including the Van Duzen, Middle Fork, and South Fork. From the Smith, at the Oregon border, through the Eel, the rivers are relatively dam-free and clean, with much of their watershed acreages in public ownership, with surviving though imperiled runs of salmon and Steelhead, and with far less development pressure than elsewhere. Though not without problems, this watery hinterland of northern California is one of the most outstanding regions of wild rivers in America. South of the Eel, the rivers are relatively small, except for the Russian as it flows through an interior valley toward San Francisco Bay but then turns sharply out to sea.
Sacramento Basin
Draining the interior of northern California, this is the state's largest river, carrying about 31 percent of total runoff. Steep headwaters foam through shading forests until trapped behind Shasta Dam, followed by a long passage through the northern half of the Central Valley, where most of the frontage is confined by levees and farmland.
The Pit—a tributary that's larger in volume and longer than the Sacramento where they meet—collects hearty spring discharges of the Fall River along with Hat and Burney creeks. This remote northeastern corner of California is the fly-fisherman's paradise, with spring creeks that rival the legendary streams of Yellowstone. Farther south, a series of fairly intact creeks aim west from Lassen Peak at the southern limits of the Cascade Mountains.
A small set of Sacramento tributaries drains the eastern slope of the coastal mountains, but most streams there sink into gravel or are depleted for irrigation before reaching the river. In the lower basin, Cache Creek is the largest Sacramento tributary from the west and carves wild canyons.
The third set of tributaries drains the Sierra Nevada and provide by far the greatest flows to the Sacramento, beginning with the Feather River and continuing through the American. The lower Sacramento eases past the state capital nearly at sea level, and just below, the Sacramento Delta is one of the largest deltas in the nation.
San Joaquin Basin
California's third hydrologic region, the San Joaquin River Basin covers the southern half of the Sierra and occupies the southern Central Valley. Though it's larger than the Sacramento Basin in area, precipitation decreases in the south, so this river carries only 11 percent of the state's runoff—one-third the Sacramento's volume—and most is diverted by irrigators. Nearly all the water comes from Sierra Nevada tributaries extending from the Cosumnes south through the high-mountain headwaters of the San Joaquin.
South of the San Joaquin, the added volume of the Tulare Lake Basin, which historically overflowed into the San Joaquin, would raise the greater San Joaquin's total to about 16 percent of California runoff. Flowing toward the dried-up Tulare Lake, the Kings River churns from alpine terrain through its Middle and South forks in Kings Canyon National Park. The Kaweah, Tule, and Kern likewise flow from high mountains to the southern Central Valley.
All the major San Joaquin tributaries are dammed except the diminutive Cosumnes and Clavey, along with some forks of the larger streams. Hydropower dams were built even at high elevations. Yet impressive free-flowing mileage remains. Stellar reaches in the Sierra Nevada later tumble with rapids through the pines, oaks, and chaparral of the foothills, followed by languid windings through the CentralValley. These lower reaches are typically entrenched with wooded banks 10 to 20 feet high and farmland just beyond. Occasional parks are found, but most valley reaches are inaccessible to the public. The west side of the San Joaquin Valley—draining the interior Coast Range—sees little runoff because of a dry climate, the intervening Salinas River Valley to the west, and the rain-shadow effect of coastal mountains.
Central and South Coast
The state's fourth hydrologic region is composed of the rivers at the Central and South coasts and accounts for 5 percent of statewide runoff. Streams flush quickly from the 500-mile-long Coast Range that rises south of San Francisco—longer than the Sierra but producing a small fraction of the water. Springtime—with streams flowing, riparian forests leafing, and hillsides green with grass and flowers—is the best time to see these small rivers.
The San Lorenzo is a major stream of the Central Coast as it bubbles down from redwood forests of the Santa Cruz Mountains. On the east side of the coastal mountains, the depleted Salinas riffles north to Monterey Bay. Along the South Coast, streams are even smaller. As they exit rugged canyons they drop bedloads of gravel in broad alluvial plains where remaining water seeps underground except during peak storms.
Eastern Sierra Nevada
Rivers of the Eastern Sierra account for only 4.5 percent of statewide runoff but are spectacular with steep gradients; this is unlike any other group of streams in America. The Truckee, Carson, and Walker fall from the Sierra escarpment. To the south, the Owens River picks up Sierra snowmelt from stunning tributaries and takes a remarkable path through the desert before being diverted to Los Angeles.
Deserts
In one of America's driest regions, these streams provide only 0.3 percent of the California runoff, not including the giant Colorado River, whose volume comes entirely from other states. In the heart of the Mojave Desert, the Amargosa River ends in Death Valley. Palm Canyon Creek nourishes rare oases of fan palms. Marking the border of California and Arizona, the Colorado carries prodigious runoff from the Rocky Mountains but is completely tapped before reaching its estuary at the Gulf of California in Mexico.
All these rivers and streams are formed and governed by the great natural systems that surround them. Geologic processes and climate shape the hydrologic makeup of each stream and ultimately determine what plants and animals will thrive. Those natural processes and the life forms they support are the topics of the next section.
THE NATURAL HISTORY OF RIVERS
The fundamental nature of any river—the way it looks and works—is a result of five factors. First, geologic events created the mountain ranges, topography, and bedrock that a river flows through—the big backdrop. Second, climate governs the amount and timing of the all-important rain and snow. Third, the forces of geology and climate together determine the hydrology, or characteristics of flow, including cycles of floods and drought. This flow is what has sculpted valleys and canyons into the profiles we recognize today, and it continues to determine the morphology or shape of riverbeds as well as that of shorelines and floodplains. Fourth, the combined effects of geology, climate, and hydrology govern what plants can live in and along a river. Finally, plant life and all the other factors define what fish and wildlife will thrive. Fascinating relationships between flora and fauna affect the population and health of each species. The extraordinary physical and biological diversity of California rivers is due to the multitude of ways that all these interactions vary across the state.
Geology
Plate tectonics is the process that initially created the landscapes we now know. Distinct sections of the earth's crust float on a mantle and molten core, which allow the surface crust to move. In and along California, the Pacific Plate is slowly migrating north along the edge of the North American Plate, and the abrasive meeting place of the two is the San Andreas and related faults. The Pacific Plate boundary turns sharply out to sea at Cape Mendocino (not the town of Mendocino, but the westward-jutting headland north of the Mattole River), where the undersea Gorda Plate lies next to the North American Plate. Most of this heavier sea-bottom plate is pushed underground while the larger, lighter terrestrial plate glides westward over it. In the process, fragments of the down-bound crust break off at the subduction zone and accumulate as the Coast Ranges. As the subducted material is buried deeper and deeper, it heats, melts, and later erupts in volcanoes of the southern Cascade Range including Shasta and Lassen. A similar tectonic process formed the Sierra Nevada. Here a pluton of molten underground rock hardened into granite and then through faulting emerged to become the spectacular mountain chain we know, once overlying rock eroded away. Meanwhile, the Great Basin landscape east of the Sierra has been rifting or spreading apart to form parallel ranges that trap waters traveling between them. With this creation story of plate tectonics and mountain formation in mind, we'll now consider some of the geologic forces specifically affecting rivers (for individual streams, see the river profiles).
In northwestern California, ancient plates or terranes long ago collided with the West Coast and pushed up today's more easterly outliers of the Coast Range complex—for example, the Marble and Yolla Bolly ranges. Rivers forming in these mountains and progressing seaward became blocked by the rising of the newer and westerly coastal ranges and repeatedly found their paths of least resistance along the weakest rock strata following fault lines. These typically run northwest to southeast (parallel to the plate boundaries), and a number of streams flow on strikingly similar northwest routes to the ocean. This cant is evident at the lower Smith, Klamath, and Trinity; also in the northwest aim of Redwood Creek, Mad River, and the Mattole; and along much of the Eel and its South Fork (see map). The more southerly Russian and Salinas rivers parallel northwest–southeast fault lines in similar ways.
Pushed up by tectonic action where the Pacific and North American plates meet, and stretching north to south along much of the coastal edge of northern California, the Franciscan Complex is a large formation of mixed rock scraped off the bottom of ancient seafloors. Thoroughly fractured by seismic action, it was crumpled against the western edge of North America as part of the Coast Ranges. This broken, bent, and altered rock is highly susceptible to weathering, and is one reason that North Coast rivers have exceptionally erodible watersheds. The Eel, for example, carries the highest load of sediment as a percentage of water volume in the United States—even higher than the muddy Mississippi (one would not guess this from the Eel's lucid green pools in summer; the silt is transported mostly during winter floods).
Farther inland, but still within the Coast and Klamath ranges, millions of years of seismic activity have mixed soft rock strata with outcrops of harder sandstone and granite. Where these resistant formations intersect with rivers, they create rapids. Gabbro and basalt are also hard rocks that resist erosion and result in gorges such as Oregon Hole on the Middle Fork Smith and Burnt Ranch on the Trinity. Throughout the greater coastal ranges, metamorphic and sedimentary rocks from previous ocean floors generally characterize the stream channels, unlike the northeast and the Sierra Nevada, where igneous rocks either monopolize or dominate.
In the northeastern reaches of the state, the Cascade Mountains were formed by volcanic eruptions. These included the great volcanoes, Shasta and Lassen, and also widespread lava flows at lower elevations. Once it hardens, lava is porous and allows water to accumulate in air spaces. These subterranean reservoirs ultimately discharge as groundwater and contribute to the network of spring-fed streams at the Modoc Plateau and Cascades. The Fall, Pit, McCloud, upper Sacramento, and Shasta rivers are all fed by spring discharges that emanate from hardened lava.
Lava serially seeped out of the earth in sheets, forming layers up to several hundred feet thick. This hard rock now resists erosion, and so streams in the volcanic regions drop over falls when they come to a fracture or to the edge of a lava formation. Burney Falls and the falls of the McCloud are spectacular examples.
All these northeastern groundwater-fed streams have cold currents due to the dark and chilled nature of their underground sources. They also have relatively steady flows, because the groundwater seeps slowly as spring discharges from natural reservoirs. The dual qualities of coldness and steadiness make these rivers prime trout habitat.
Though it's not plentiful in the north or statewide, limestone is another ingredient that makes for biologically rich waters. Where it does occur, the carbonate breakdown products provide excellent building blocks for aquatic life. Even without limestone, many California streams are somewhat endowed with calcium, and with it, mussels and crustaceans readily form their shells and carapaces, and aquatic insects multiply, together forming the basis of aquatic food chains that support a host of fish, birds, and other wildlife.
South of the volcanic Cascades, the signature rock of the Sierra Nevada's 400-mile-long range is granite. Boulders, cobbles, and gravel of gray and nearly white granite typify rivers from the North Fork of the Feather southward through the Kern. Unlike the porous volcanic rock of the Cascades, the Sierra granite sheds snowmelt rapidly in flushes of springtime and early-summer runoff followed by several months of low flow. In the high Sierra, rapids are often formed when rockslides of the resistant granite clog river channels. The magnificent waterfalls that characterize upper sections of many Sierra streams—especially from the Tuolumne southward—occur where water flows over massive slabs of granite. Other waterfalls occur where tributary streams from "hanging valleys" enter larger valleys scoured deep by glaciation. Ice filled these larger valleys to a height where the tributaries and their own glaciers flowed directly onto the great mass of trunk ice, and were unable to keep pace with the erosive rate, as side streams usually do.
(Continues...)
Excerpted from Field Guide to California Rivers by Tim Palmer, William E. Avery. Copyright © 2012 The Regents of the University of California. Excerpted by permission of UNIVERSITY OF CALIFORNIA PRESS.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.
Table of Contents
Welcome to the World of California RiversAcknowledgments
A Word of Warning
AN INTRODUCTION TO THE RIVERS
The Network of Rivers
The Natural History of Rivers
The Problems, Protection, and Restoration of California Rivers
Fifty Common Species of River Plants and Animals
RIVER PROFILES
North Coast
Sacramento Basin
San Joaquin Basin
Central and South Coast
Eastern Sierra Nevada
Deserts
Appendices
Sources
Additional Captions
Index
What People are Saying About This
"Here's the definitive field guide on the Golden State's rivers. . . . Whether you fish, kayak, or just enjoy exploring on foot the banks of these waterways, this is a book you will want to have at your fingertips."—Salinas Californian
"It belongs in every river lover's book collection, boat, and backpack. . . . Anyone exploring California rivers will want this book!"—Birdbooker Report
"An excellent little guide, this is one book you won't want to leave home without if you plan on river rafting, hiking, or a fishing trip."—Bookloons.com
"One of an extensive series of compact, lushly photographed and illustrated guides put out by the UC Press on the naturalist's paradise that is California."—Sf / Sacramento Book Rev / 1776 Prod