The Salmon River watershed is located in the Klamath Mountains of far Northwestern California. The sub-ranges of the Trinity Alps, Russians, Marble Mountains, and the Salmon Mountains form rugged topography that is deeply incised by the river and its tributaries. Nearly all of the watershed is forested.
Almost 99% of the watershed is public land and is managed by the US Forest Service as the Klamath National Forest. The national forest itself lies at the heart of a vast region of publicly-owned land--mostly National Forest but also BLM, state, US Fish & Wildlife Service, and National Park Service land--that includes much of Southwest Oregon and Northwest California. The larger region, known as the Klamath-Siskiyou Bioregion, shares a distinct and rich assemblage of geological and ecological characteristics.
By volume, the Salmon River is the second largest tributary to the much larger Klamath River system (the Trinity River is the largest tributary). There are no dams, diversions, or significant irrigation withdrawals in the Salmon River watershed. Additionally, there are no dams or barriers between the Salmon River and the Pacific Ocean, making the river completely accessible to anadromous fish.
The watershed occupies 1,945 km² (751 mi²) in the southwestern corner of Siskiyou County. The watershed’s southern divide adjoins Trinity County and Humboldt County. The river has a 29 kilometer (18 mile) long mainstem and two longer forks, the North Fork and the South Fork. The confluence of the two forks is in Forks of Salmon, California. Wooley Creek is the largest direct tributary to the mainstem and, by flow volume, is often just slightly smaller than the North Fork. Elevations in the watershed range from 139 meters (456 feet) at its mouth to 2,609 meters (8,560 feet) at Caribou Mountain in the Trinity Alps.
The Salmon River experiences a Mediterranean climate. Summers are hot, sunny, and very dry as a seasonally-permanent high pressure system dominates the weather. Thunderstorms are infrequent and typically do not produce much, if any, precipitation. Winters are cool, cloudy, and wet as progressive synoptic-scale weather systems alternately bring storm systems from the southwest and cold air from the north. The area receives nearly all of its annual precipitation between November and May.
Microclimates vary substantially throughout the watershed due to elevation, aspect, wind protection, proximity to rivers and lakes, and solar exposure. The wettest area in the watershed is on the Crapo Mountain triple divide between Wooley Creek, the Little North Fork, and upper North Fork in the southern Marble Mountains. However, the South Fork Salmon River typically has the greater flow of the two forks due to its larger drainage and higher elevations.
The Salmon River watershed has a complex geologic history. The rocks forming the Klamath Mountains began as sea floor sediments off the West coast of North America about 380 million years ago. Then between 170 and 120 million years ago, these compacted sediments and some attached oceanic crust were uplifted by tectonic forces during a major mountain-building event. The Sierra Nevada range was formed during this same time period and bears close geologic relationships to the Klamath Mountains.
Shortly after the initial creation of the Klamath Mountains, continuing subsurface activity caused molten magma to intrude into the core of the mountains. This magma slowly cooled to form the granite which can be seen today in the Wooley Creek watershed, the English Peak area on the North Fork and in the Trinity Alps. Hot liquids associated with the magma deposited minerals—including gold—in the surrounding rock.
Following this, the young (and still uplifting) Klamath Mountains were surrounded by a shallow ocean, creating an island just off the coast of North America. Eroded sediments from the mountains were deposited in this shallow sea before sea levels dropped in the Tertiary Period, about 65 million years ago. Since that time the Klamath Mountain have been slowly eroding, ultimately forming the combination of sharp and rounded peaks we see today.
The Salmon River watershed has experienced at least four major glacial periods within the past two million years, the most recent of which ended about 13,000 years ago. These repeated glacial events carved signature U-shaped glacial valleys and left behind the multitude of glacial lakes and moraines we find in the high country today. The last remaining glacier in the Klamath Mountains is on Thompson Peak in the Trinity Alps, just over the divide in the Trinity River watershed. Caribou Mountain, the highest peak in the Salmon River watershed has perennial ice fields.
The Salmon River system displays a dendritic drainage pattern.
The river itself carries a high bedload of coarse (gravel to boulder-sized) material and, except in periods of flood, a low suspended load. The result is a boulder-lined channel and banks in areas of low gradient, bedrock channel and banks in high gradient reaches, and translucent water quality.
The Salmon River is now fairly quiet in geologic terms. Erosion continues to be the primary force at work. Landslides and rock falls occur frequently, sometimes blocking roads or the river itself. Occasionally, rather small earthquakes are centered in or near the watershed.
The Salmon River is one of the most biologically intact river systems in the Western United States.
There are no polluting industries, agriculture, or municipal centers in the watershed, making it the most pristine major tributary of the entire 41,000 km² (16,000 mi²) Klamath River system.
The Salmon River provides abundant amounts of clean, cool water into the Klamath River system ( gallons per minute as you read this). In late summer, this cool water is crucial to the survival of migrating salmon. The Salmon River has long been renowned for its exceptionally high quality waters.
The Salmon River hosts all native anadromous fish runs present in the Klamath watershed: spring Chinook, fall Chinook, coho, steelhead, green sturgeon, and Pacific lamprey. Unlike all other major tributaries to the Klamath (and most other Pacific rivers) there are no hatchery fish in the Salmon River. All runs retain their full wild character and genetics, making the Salmon River a repository of anadromous fish genetics that can be used to help restore fish runs in the rest of the Klamath watershed.
Despite this, the fishery of the Salmon River is a remnant of what it once was. Several species of the river's fish are at risk of extinction in the Klamath watershed: summer and winter runs of wild Klamath Mountains Province Steelhead, spring and fall Chinook salmon, and coho salmon.
Beginning in the 1850's, large scale hydraulic mining and related activities greatly altered the river channel, tributaries, and riparian areas. The naturally translucent green river probably flowed rich with brown, redd-choking sediment for several decades. River temperatures have likely increased due to reduced shade cover. The fishery suffered immensely but due to a lack of any reliable record keeping, we will never know for sure just how much things changed. Various anecdotal accounts refer to massive historic fish runs.
Logging, road-building, wildfire, and over-fishing at sea have also substantially compromised the fishery. Compromised water quality and high summer water temperatures in the Klamath River--caused primarily by a series of dams and reservoirs far upriver--affect both in- and out-migrating fish from the Salmon River.
Recent fish counts indicate alarmingly low fish populations some years--especially for Spring Chinook--and only small to modest populations in better years.
The Salmon River lies at an important biological corridor connecting the interior Basin and Range biomes with the Pacific Coast. Many plants and animals find the combination of geology, climate and biology to be ideal habitat and make the Salmon River watershed their home. Others see a prime migration corridor and move through the area to spread their populations to others points or on their way to or from their seasonal homes. The Salmon River lies between the coastal and interior routes of the Pacific Flyway and is a transitory home for dozens of varieties of migrating birds.
The watershed is a land of biodiversity superlatives and is one of the key areas of biodiversity in the Pacific Northwest. It boasts one of the greatest coniferous tree diversities in the world (including endemics, such as the Brewer spruce), a convergence of trees found in both Alaska and Mexico, a wide variety of Ceanothus species, and astoundingly diverse butterfly and forest-type mollusk populations. The world’s largest diameter incense cedar grows high in the Little North Fork drainage within the Marble Mountain Wilderness Area.
Part of the explanation for this extraordinary biodiversity lies in the geologic history of the Klamath Mountains. During the Wisconsin Glaciation from about 25,000 to 13,000 years ago, this area escaped the burden of continental ice coverage and served as a biologic refugia for plant and animal species not adapted to glacial climates. After the glaciers retreated from areas to the north, these species remained in the cool, high elevations of the Klamath Mountains where they can still be found. Some species, such as the Brewer Spruce, Port Orford Cedar, and Sadler Oak no longer exist anywhere else.
The Klamath-Siskiyou Bioregion, in which the Salmon River flows, is a global center of biodiversity and has been designated as a UNESCO World Heritage Site, a UNESCO Biosphere Reserve, and an Area of Global Botanical Significance by the World Conservation Union.
Forty-six percent of the Salmon River watershed is federally-designated wilderness in the Marble Mountain, Trinity Alps, and Russian Wilderness Areas.
An additional 25% of the watershed is classified as Late Successional Reserve (LSR) under the Northwest Forest Plan. LSR is to be managed to protect and enhance conditions of late successional and old-growth forest ecosystems.
California governor Ronald Reagan signed the California Wild and Scenic Rivers Act in 1972, designating the North Fork, South Fork, mainstem Salmon River, and Wooley Creek as state Wild and Scenic Rivers. These same sections of river were added to the federal Wild and Scenic Rivers System on January 19, 1981 for their outstandingly remarkable fisheries. A total of 98 km (61 miles) of river are currently designated as either wild, scenic, or recreational.
Wild and Scenic designation prohibits federal or federally-licensed damming or diverting of the river and mandates that federal agencies manage the river and its corridor to enhance and protect its free-flowing character and the values for which it was designated. Sections of river designated as wild, such as the upper NF Salmon and Wooley Creek, are withdrawn from mineral entry. Private lands are unaffected by Wild and Scenic status, however, government agencies may provide assistance to willing private landowners so that their riverside land is properly in accordance with Wild and Scenic principles.
The Klamath River is also a designated Wild & Scenic river, creating source-to-sea Wild and Scenic status for waters originating in the Salmon River. Combined, the North Fork Salmon, mainstem Salmon, and Klamath River constitute the second-longest continuous reach of designated Wild and Scenic river in the contiguous United States (over 177 km / 110 miles).
The high biological integrity of the Salmon River is a function of its remote location, high percentage of public ownership (98.7%), and proportion of legally protected land area. The absence of alluvial valleys in the watershed has limited development and settlement.
Large tracts of inventoried roadless area remain unprotected and vulnerable to harmful land use practices such as road building, mining, and commercial logging.
A substantial portion of non-Wilderness land in the watershed has been logged and roaded. The impacts of past land management are evident.
The watershed is a fire-dependent landscape and, as such, experiences frequent wildfires. Most are relatively small, however, several major wildfire complexes have burned in recent history. More than 69% of the watershed has burned since 1911 with some of these areas burning multiple times. Changes in the natural fire regime have exacerbated wildfire frequency and severity. Read more about the fire history of the Salmon River.