South Fork Trinity River

The South Fork Trinity River is a major tributary of the Trinity River, in the northern part of the U.S. state of California.^[1] It is part of the Klamath River drainage basin. It flows generally northwest from its source in the Klamath Mountains, draining about 980 square miles (2,500 km²) of mountainous terrain. Flowing from its headwaters in the Yolla Bolly Mountains 92 miles (148 km) through Humboldt and Trinity Counties, tributaries to the undammed and Wild and Scenic-designated river include Hayfork Creek and the East Branch South Fork Trinity.^[2] The river lies in very remote topography and is one of the least developed tributaries of the Trinity River. The resulting pristine habitat is important for several endangered species and rare plants. Historically, the South Fork Trinity was known for its prodigious anadromous fish population and dense old-growth forests, but extensive logging and resource exploitation in the watershed have hurt both of these resources.^[3]

Course

The South Fork Trinity River begins in a semicircular amphitheater on the west slope of the Brooks Ridge near North Yolla Bolly Mountain, and winds northwest for a distance variously stated to be from 60 to 92 miles (97 to 148 km). The headwaters are in an unnamed spring at an elevation of 4,460 feet (1,360 m).^[1] From there, it flows west briefly and turns to the north, receiving numerous small tributaries that together form its headwaters in a series of steep and forested valleys. At about 4 miles (6.4 km) from its source, the Humboldt Trail drops down to river elevation and crosses it, and the river receives north-flowing Shell Mountain Creek from the left. Not long after this point, the East Branch South Fork Trinity River flows in from the right, after having traveled north then west a distance of about 10 miles (16 km).^[1][4][5]

The South Fork then shortly after receives Happy Camp Creek from the left and Smoky Creek from the right, then entering an increasingly wide valley, it receives Rattlesnake Creek on the right and flows by the town of Forest Glen, which is also on the right, crossing underneath California State Route 36. Steadily increasing in volume, the river winds west then turns north, sweeping across the valley floor in wide arcs. At this point, it begins to parallel the Mad River, separated by an approximately 2,000-foot (610 m) divide. The valley then narrows again and turns northeast, while the river receives the water of Butter Creek, and its tributary Indian Valley Creek, on the right bank.^[1][4][5]

The river then enters the far wider Hyampom Valley, where Hayfork Creek, its largest tributary, enters from the right as the river winds past the town of Hyampom. It then passes the Hyampom Airport also on the right bank while receiving Pelletreau Creek from the left. Here, the river is already wide and powerful, winding across a braided channel through a wide floodplain. The river enters another narrow canyon, thundering northwest through frequent rapids. It receives Mingo Creek, which has its source in a small meadow from the left, then veers sharply eastward and then turns sharply north. Flowing west then turning sharply east around a ridge, the river receives Madden Creek from the left and crosses underneath California State Route 299. Directly after this stream crossing, the South Fork meets the Trinity River.^[1][4][5]

Geology

Over hundreds of millions of years, the westward movement of North America caused it to accrete many terranes from the Pacific Ocean region along its west coast. Four major terranes have so far collided with the northwest coast of California—the oldest dating to pre-Jurassic times—crumpling the crust upwards into the 10,000-foot (3,000 m)-high massif of the Klamath Mountains. Most of the Klamath Mountains consist of granite and batholiths underlie most of the major peaks. The second most recent of the terranes—dating to the Cretaceous—which is composed almost entirely of granite, brought with it a strip of mica that roughly aligns with the present course of the South Fork Trinity River. The mica caused the granite to become weaker than the surrounding rock, so this area was subjected to greater erosion that created the valley of the South Fork, the lower Trinity River, and the lower Klamath River. This is also why the Klamath and Trinity rivers have this sharp northwest bend on their generally southwest courses, and the South Fork Trinity River valley is the southernmost extension of the roughly 200-mile (320 km)-long gorge formed by this abundance of mica.

The vast majority of the South Fork watershed is mountains, with the only level land found in the Hyampom Valley at the confluence of the river and Hayfork Creek, along the Hayfork valley, and along narrow river terraces. There are large parts of the watershed where the ground is composed of stable bedrock, while large portions of hillsides are composed of loose soil and rock. Historically, riverbeds in the watershed were narrow and rocky, but due to vast amounts of silt washed down by poor logging practices, streambeds have become wide, braided, elevated and shallow.^[6]

Watershed

The river and its tributaries drain 980 square miles (2,500 km²) in Humboldt County in the south and Trinity County in the north, comprising 34 percent of the 2,853-square-mile (7,390 km²) Trinity River watershed. The Hayfork Creek sub-watershed contains 379 square miles (980 km²), or 38 percent of the entire South Fork Trinity watershed. Most of the watershed lies on public lands (79 percent), while for Hayfork Creek, 78 percent of its watershed lies on public lands.^[2] With the Yolla Bolly Mountains in the south and the Klamath Mountains in the north, the topography of the South Fork Trinity's watershed is dissected by deep gorges and valleys separated by narrow ridges. The South Fork is the largest and longest undammed National Wild and Scenic River in California.^[7] (The Eel River, also a Wild and Scenic River, is over twice as long, but is dammed near its headwaters.)

While along the length of the South Fork itself there is little human development, it receives agricultural pollutants from Hayfork Creek, whose valley contains over 52,000 acres (210 km²) of ranchlands and farmlands. In fact, there have been sightings of frequent fish kills in Hayfork Creek and it is said to have "severe water quality problems in the summer".^[6] Diversions off Hayfork Creek have only furthered the pollution problem by concentrating it. Logging and road-building are the two primary negative factors affecting the South Fork mainstem. Clearing hillsides has accelerated erosion, clouding the water and causing difficulties for steelhead trout and chinook salmon, which once spawned in the river in prodigious numbers. Although logging has mostly ceased since the designation of the national forest, the landscape has not yet fully recovered from its impacts.^[3]

Much of the South Fork Trinity River's watershed is the Shasta-Trinity National Forest, which covers most of the mountainous areas in the southern and central part of the watershed, and the Six Rivers National Forest, which covers most of the northern third of the basin. Nearly the entire length of the South Fork above the Hayfork Creek confluence is inside the Shasta-Trinity National Forest, while below the confluence, national forest lands peter out into privately owned land and the river then enters Six Rivers National Forest. Most of the upper and lower Hayfork Creek reaches also are in the Shasta-Trinity forest, while a large amount of private land surrounds its middle reach. Throughout nearly the entire watershed, there are sporadic patches of private lands and Bureau of Land Management-owned lands.^[5]

Streamflow

The United States Geological Survey monitors the South Fork Trinity River's flow at four gauges; these are at Salyer, downstream of Hyampom, at Hyampom upstream of the Hayfork Creek confluence, and Forest Glen (from mouth to source).^[8] The average flow of the river at its mouth is 1,807 cubic feet per second (51.2 m³/s).^[9] For Salyer, closest to the mouth, the highest peak flow was 95,400 cubic feet per second (2,700 m³/s) on January 20 in the 1964 flood, while the lowest was 8,480 cubic feet per second (240 m³/s) on 31 December 1954.^[10] For the location downstream of Hyampom, the highest recorded peak flow was 88,000 cubic feet per second (2,500 m³/s) on 22 December 1964, while the lowest was 620 cubic feet per second (18 m³/s).^[11] For the location at Hyampom, the highest peak was 57,000 cubic feet per second (1,600 m³/s) on 22 December 1964, while the lowest was 5,020 cubic feet per second (142 m³/s) on 13 February 1962.^[12] For Forest Glen, the largest peak was 41,200 cubic feet per second (1,170 m³/s) on 22 December 1964, and the lowest was 3,530 cubic feet per second (100 m³/s) on 13 February 1962.^[13]

History

For a yet unclear length of time likely stretching into the hundreds of years, the South Fork Trinity River had a rich history of Native Americans. The river annually produced enormous salmon runs, one of the richest sub-basins in the Trinity watershed, and virgin old-growth forests covered most of the watershed. In the 19th century, many events the largest of which was the California Gold Rush spurred Europeans, Americans and others to flood the region in search of furs, and later gold. One particular trail crossed through the Yolla Bolly Mountains, then wound down to Hayfork Creek and west to the South Fork Trinity.^[14]

In the 1930s, hydraulic mining was already taking place at the Swanson Mine near the mouth of the river. Beginning in the late 1940s, logging activity took place on mountainsides in the South Fork Trinity's watershed. It was said that the "big logging started when Pat Veneer came in",^[15] referring to a logging company from the state of Oregon. It was not long before debris and silt began to cloud the creeks feeding the South Fork, many of which were still located on United States Forest Service land. In the 1960s, specifically in 1964, heavy rains washed enormous amounts of silt from logged lands into the river and its tributaries, clouding the water and killing enormous quantities of wildlife. The flood peaked on 22 December at 95,400 cubic feet per second (2,700 m³/s).^[16] It was said that the "South Fork is a lost cause, a dead river which will never recover from the devastation of the 1964 storms.^[15] In the 1970s, anadromous fish populations finally began to decline as a direct result of this constant clouding.

In 1947, Six Rivers National Forest, which encompasses most of the northernmost quarter of the South Fork Trinity's watershed, was established.^[17] By 1954, the Shasta-Trinity National Forest, which covers the vast majority of the South Fork Trinity River's watershed, was established, bringing nearly 70 percent^[5] of the South Fork watershed under federal protection.^[18][19] In 1980, the United States Forest Service designated the South Fork National Recreation Trail, which runs from Forest Glen to near its headwaters.^[14]

Fish and wildlife

In 1964 before the floods, the spring chinook salmon run was estimated to be as large as 10,000 and with a minimum of 3,400, which declined to an annual run of between 345 and 2,460 prior to 1990. Due to the gradual recovery of the mountainsides after logging, salmon runs have once again begun to return, averaging 2,000 to 4,000.^[20] Although the water from the South Fork continues down the Trinity to the Klamath and eventually, the Pacific Ocean, undammed, the diversion of most of the Trinity mainstem's water and pollution in the Klamath have made difficult access to the river by migrating fish. It is of note that part of the reason of the declined population is a high mortality rate of female salmon, resulting in less offspring. Generally in summer, temperatures in the river can rise to over 80 degrees Fahrenheit (27 degrees Celsius), during which introduced species, including green sunfish.^[6]

Remaining old-growth forests in the South Fork watershed provide vital habitat for several threatened and near-threatened species, including the Northern Spotted Owl and wolverine.^[3]

See also

• South Fork Eel River, which has ecology, geography, and a history of logging very similar to that of the South Fork Trinity.
• List of rivers of California

References

External links

• South Fork Trinity River Watershed Restoration Projects