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...

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...

California rivers make possible a diverse assemblage of fish, birds, and other wildlife. They deliver the water used in cities and towns, and provide for a large share of the nation’s food production. They nourish important fisheries in the ocean. They transport sand needed to replenish ocean beaches, and they offer recreation to millions of people, along with the opportunity for everyone to know a small part of the original California. But most of the streams have been severely diminished from what nature once provided. Regarding just one species of fish, the charismatic Chinook salmon, biologist Peter Moyle wrote in...

Drawings and descriptions of 50 plants and animals in and along California’s rivers follow. This limited cast of characters barely scratches the surface of what you’ll see along the water, but it includes many of the most common or important life forms.

A valuable member of the riparian community offering shade, shelter, and food, box elders grow at streamfronts across much of California except the desert. Maplelike seeds are relished by squirrels and songbirds, and the seeds, bark, and twigs are especially important in the diets of Evening Grosbeaks, porcupines, and deer. Compound trifoliate leaves look a lot like poison...

As the heart ofField Guide to California Rivers, this part of the book offers profiles of 150 different waterways and mentions many others. Streams have been selected based on importance, size, biologic significance, and appeal for hiking, fishing, and nonmotorized boating. They’re organized by larger hydrologic regions and appear from north to south.

Space doesn’t allow for some of the finer details about hiking, fishing, or boating, but I strived to include enough guidance for you to successfully explore on your own. Keep in mind that conditions change, and always watch for hazards not identified here. I find surprises...

The Smith is the largest completely undammed river in California, and the entire watershed is one of the best-protected major basins on the West Coast. It empties into the Pacific 3 miles south of Oregon. The main stem forms at the South Fork Middle Fork confluence, and the final 12 miles glide across a coastal plain to a spectacular natural mouth.

The entire watershed lies within the Siskiyou Mountains and Coast Range, and cuts through erodible rocks including the Josephine ophiolite a large formation of former oceanic crust overlying peridotite (upper mantle rock), which is often altered to serpentinite and...

As California’s largest river, the Sacramento flows south from Mount Shasta to tidewater at the city of Sacramento, then wends westward through the delta to San Francisco Bay. Only the giant Columbia carries more water into the Pacific south of Canada. The San Joaquin enters the Sacramento Basin within the delta but is considered separately in this book.

The river begins with runoff from both the Trinity Mountains and Mount Shasta of the Cascade Range and is soon impounded at Box Canyon Dam. Below this, the Sacramento runs through 36 miles of forested canyon with I-5 slicing into higher slopes...

Wedged into mid-terrain between the higher elevation American and Mokelumne basins, this watershed does not reach up to the Sierra belt of greatest snowfall, and so the stream is smaller. After winding through miles of forested mountains, the 44-milelong Middle and 49-mile North Fork join just above the Hwy. 49 bridge, 14 miles south of Placerville. The main stem then crosses foothill grasslands to the Central Valley and enters the delta at the far-northern extent of the San Joaquin Basin.

The Cosumnes is often cited as the only dam-free Sierra river. Yet the South Fork Merced, Middle Fork Kings, and...

The second-largest stream between the Golden Gate and Monterey Bay, heavily forested Pescadero Creek runs to sea from the Santa Cruz Mountains. It flows through Portola State Park and the expansive Pescadero Creek County Park, which combined with adjacent reserves total 8,000 acres. Steelhead and a few Coho Salmon spawn here, with potential for restoration. The lower creek meanders through one of the larger coastal marshlands.

An Army Corps of Engineers dam proposed in 1971 would have flooded much of the creek up to the county park, but was defeated by citizen action. Subsequent plans to develop the area were...

Beginning in the Caribou Wilderness east of Lassen Peak, this small river runs southeast through a forested canyon to Susanville. The flows that remain undiverted supply the landlocked and evanescent Honey Lake in the Great Basin.

Lower reaches can be seen by walking or mountain biking along a National Recreation Trail—an abandoned railroad grade climbing west from the Susanville Depot through the Susan River Canyon for 16 miles. In Susanville, go west on Rte. 36, turn left on Weatherlow Street, go half a mile, and park at the historic depot. Fall colors are good along the trail in late...

The obscure Amargosa is the state’s only reasonably intact river system in the vast Mojave and Sonoran deserts, which comprise 12 percent of the state. It’s also the only California stream that lies fully in the desert area from source to mouth. The channel is usually dry except for one section and for flash floods and very wet years.

Responding to the seismically riven landscape of the Great Basin, this watercourse dodges the Amargosa Range and related mountains by trending south, west, and finally north. Its path begins in the aptly named Thirsty Canyon of the Nevada Test Site, flows...