Amphibian and Reptile Studies of the Trinity River Riparian Zone

The U.S. Forest Service Research Experiment Station in Arcata, California (Redwood Sciences Lab) conducted extensive studies of use of Trinity River riparian habitats by amphibians and reptiles between Lewiston Dam and the North Fork Trinity River. The studies focused on two species of concern, the yellow-legged frog and the western pond turtle. Direct observation and pit traps were the two methods of enumerating biota. Maps of yellow-legged frog and western pond turtle locations as well as riparian habitat types are contained in KRIS Map. Data under amphibian/reptile topic in KRIS Main Trinity is from Wilson et al. (1991). See also Lind and Welsh (1996). See the Redwood Sciences Lab website ( for more publications.

Riparian Assessment

Changes in riparian conditions along the Trinity River from Lewiston to Douglas City were analyzed by Randy Wilson at the U.S. Forest Service Research Experiment Station in Arcata, CA (Redwood Sciences Lab). Stereo pairs of aerial photographs were studied from 1960, before dam construction on the Trinity River, and from 1989. Vegetation types, gravel bar, bedrock and other features were identified and mapped and the width of the riparian zone measured. Mapping was done in PC Arc Info at both Redwood Sciences Lab and at BLM in Redding. For a complete description of methods of analysis and findings see Wilson (1993).

Lower Trinity Mainstem Fall Chinook Salmon Redd Counts and Creel Census 

The Hoopa Tribe Fisheries Department has collected very useful data on lower mainstem Trinity River: fall chinook redd numbers by reach and angler catch of salmon and steelhead. The redd data were collected on five reaches of the mainstem Trinity River that extend from Hawkins Bar to Weitchpec. Creel census data are gathered from Willow Creek downstream to the Hoopa Square. Only data through 2001 were available for KRIS Version 3.0, and creel data for 1996 were not used because they covered a different area than 1997-2001 surveys. There were no redd surveys conducted in 1998.

Trinity River Salmon and Steelhead Adult Population Assessment

The California Department of Fish and Game has the responsibility of estimating salmon and steelhead populations in the Trinity River basin. Weirs have been erected to intercept salmon and steelhead so that they can be counted and tagged at Willow Creek and Junction City. All adult salmonids captured are measured and a sub-sample are marked. Tagged fish are recovered in sport fisheries, during carcass surveys and at Trinity River Hatchery. The population estimates are done by using a ratio of the tagged versus untagged fish counted. All data are reported annually in the Klamath River Basin Fall Chinook Salmon Spawner Escapement, In-river Harvest and Run-size Estimates (CDFG, 2003).

Carcass and redd counts are conducted between mid-September and late-December. The length and sex of fish are noted as well as if the fish are of hatchery origin. Pre-spawn mortality is also measured. The CDFG Trinity River mainstem reach designations changed somewhat between the period of  1977-1995, when surveys were from Lewiston Dam downstream to the North Fork. In more recent years, surveys have covered areas further downstream (see 2000-2002 Reaches).  

The California Department of Fish and Game has published annual reports for the Trinity River which are linked below:

Trinity Mainstem Spawning Gravel Bulk Samples, Pebble Counts, Permeability and Cross Sections  

Graham Matthews and Associates conducted the Mainstem Trinity River Spawning Gravel Quality Investigation (GMA, 2001) to: 1) establish baseline substrate composition and permeability conditions for long-term trend monitoring in the Trinity River and tributaries; 2) assess the relationship between substrate composition and permeability; (c) evaluate the longitudinal changes to gravel quality along the mainstem Trinity River to assess the influence of tributary derived sediments; and (d) estimate survival rate of eggs to fry emergence for chinook salmon along the mainstem Trinity River using several indices. The specific tools used were cross-sections, bulk samples, gravel permeability and Wolman pebble counts. Healthy salmonid spawning habitat will have fine sediment less than 14% fine sediment of 0.85 mm or less and less than 30% fine sediment of 6.4 mm or less (U.S. EPA, 1998). The 6.4 mm and smaller size class is sand sized material which is particular concern on the Trinity River where disturbance of areas with weak soil types has increased contributions of sand. See the Sediment KRIS Background page for more on sediment sampling.

Trinity River Coarse Sediment Management Plan  

The McBain and Trush (2003) Coarse Sediment Management Plan Lewiston Dam to Grass Valley Creek, Trinity River, CA provides monitoring data for the mainstem Trinity River and was prepared as a guideline for supplementing sediment-depleted reaches below Trinity and Lewiston Dams. The conceptual foundation for this plan is based on: 1) restoring fluvial geomorphic processes to the Trinity River below Lewiston Dam, by 2) restoring adequate coarse sediment storage to the channel in which the river can restore its ability to create and maintain high quality aquatic habitat, and then 3) maintaining coarse sediment storage by a combination of mechanical coarse sediment introduction, tributary sediment management, and high flow releases. 

The coarse sediment management plan was developed in two phases. Phase I, identifies potential coarse sediment addition locations, volumes and size ranges of sediment to be introduced, describes potential placement methods, and presents a monitoring program to evaluate the evolution of introduced sediments. Phase II, which will be completed at a later date, will focus on the potential use of dredge mine tailings as a source of spawning gravel for future additions to the river. The technical sections of the Phase I report present: coarse sediment introduction, including site identification, placement methods, and placement recommendations, tributary delta management, and the coarse sediment management monitoring plan.

Trinity River Basin Sediment Source Investigation 

The Sediment Source Analysis for the Mainstem Trinity River, Trinity County, CA (Graham Matthews and Assoc., 2001) assessed landsliding, surface erosion, legacy erosion sources, fluvial erosion and, channel storage. The assessment relied on photo-based mapping and considerable field verification surveys. Detailed sample plots were used to estimate the occurrence of small-scale erosional features, as well as legacy roads. Detailed road inventories were used to establish erosion rates by geologic type, road position, and road surfacing. Estimates of fluvial erosion were based field inventories and applied on a stream order basis. Sources of sediment in the Trinity River basin include landsliding (deep-seated landslides, shallow-seated landslides or debris slides, and debris flows or torrents), surface erosion (hillslope erosion and road erosion), and fluvial erosion (gullying and streambank erosion). 

The assimilated data were used to develop a sediment budget for the basin. The budget included input and output terms. Change in storage is not available for a sufficient portion of the watershed to have meaningful results. Inputs are from landsliding, road surface erosion, harvest area surface erosion, bank erosion, fluvial hillslope erosion (gullies), legacy roads and mining, and creep. Output values are based on measurements of sediment transport at the gauging stations near the confluence of each tributary with the mainstem. 

A major constraint on implementation of this study involved access limitations, primarily involving lack of access to private lands, especially industrial timberlands. Information on these private lands was only developed by indirect methods involving aerial photo analysis and GIS analysis. Sediment source and budget data shown in KRIS charts of sediment supply and transport have some qualifications regarding use, which are stated in the final report, but can be viewed as a note.

Flow Periodicity at Four Trinity River Bridges Below Lewiston Dam

McBain and Trush (2001) published the Estimation of 50-and 100-Year Tributary Accretion Floods Lewiston Dam to Treadwell Bridge, Trinity River, California. The study estimates the 50 and 100-year tributary flood magnitude at the four bridge sites between Lewiston Dam (RM 112) and Treadwell Bridge (RM 97.4) under the winter flood season (November-March) and the snowmelt runoff season (May-June). These flood magnitude estimates were made to help facilitate bridge design. The report evaluates multiple methods for estimating flood magnitudes and rates the results based on the expected accuracy of the flood magnitude prediction. The ranking is based on the quality of data, length of data, applicability of data, and applicability of analysis. Concurrent with this report, the Bureau of Reclamation is evaluating whether anticipated future Safety of Dam releases from Lewiston Dam are larger than 50 and 100-year tributary floods.

Trinity River Flow Data

Trinity River flow records are taken mostly from data collected by the U.S. Geologic Survey, except for U.S. Bureau of Reclamation data on inflow into Trinity Reservoir. Much of the flow data used in KRIS for the Trinity Basin was previously compiled by McBain and Trush for studies related to the flow evaluation. Flow duration curves are patterned after their work. For more information see McBain and Trush (1997). Flow data for years since 1997 were downloaded from the USGS Internet site and added to flow databases within KRIS. To learn more about USGS flow data and applicable terminology, see an excerpt from Wahl et al. (1995). 

Trinity River Restoration Program Summary Data

KRIS Version 3.0 contains restoration data on projects implemented between the years of 1984-2003 in the Trinity River basin. These data were collected for the Trinity River Basin Tributary Restoration Database by the Trinity River Restoration Program and Trinity County. This was done in part to provide a link between restoration projects in the tributaries and watersheds to the restoration objectives of the Trinity River Basin Fish and Management Act of 1984. For an overview of the Trinity River Restoration Program, see McBain and Trush (2002).

Data are from the following agencies and entities: Bureau of Land Management, Bureau of Reclamation, California Conservation Corps, California Department of Fish and Game, California Department of Water Resources, Five Counties Salmonid Conservation Program, Hoopa Tribal Forestry, North Coast Fisheries Restoration, Natural Resources Conservation Service-Weaverville, Trinity County Resource Conservation District, Trinity Fisheries Improvement Association, Trinity County, Trinity River Consulting, USDA Forest Service- Lower Trinity Ranger Dist., USDA Forest Service - Big Bar Ranger Dist., USDA Forest Service - Hayfork Ranger Dist., USDA Forest Service Six Rivers National Forest (Lower Trinity Ranger District (RD), Shasta-Trinity National Forest (Hayfork RD, Yolla Bolla RD, Weaverville RD), Willow Creek Community Services District and the Yurok Watershed Restoration Department.

Trinity River Downstream Migrant Trapping of Juvenile Salmonids

The U.S. Fish and Wildlife Service has been operating downstream migrant traps on the mainstem Klamath and Trinity rivers since 1989 (Craig, 1991; 1992; Goldsmith, 1994, Scheiff et al., 2001).  The Trinity River downstream migrant trap at Willow Creek is operated from February through August as flows allow and during the fall season in some years. Downstream migrants captured are identified to species, measured and a sub-sample weighed using the displacement method. The trap efficiency has been calculated since 1991, which allows an estimate of the number downstream migrants by species has been made since 1991. Comprehensive trap records from all years were shared with the KRIS project for Version 3.0 and they were integrated into one large source table, although time and budget did not allow more chart development. For a summary of recent downstream migrant trap results for both the Klamath and Trinity, including inter-annual comparisons see Scheiff et al. (2001). See the Fish Population KRIS Background page for more information.

U.S. Fish and Wildlife Service Photographs

The U.S. Fish and Wildlife Service allowed the KRIS team to copy many its photographs from the field for this project. The photos were taken by personnel from the USFWS Weaverville and Arcata offices and show side channels, feather edge projects, downstream migrant trapping and fish population estimation in side channels. Many feather edge riparian projects have been carried out to restore slow moving edge water areas along the Trinity River below Lewiston Dam to benefit juvenile chinook salmon. Riparian encroachment as a result of reduced flows after completion of the Trinity and Lewiston Dams had reduced the amount of this habitat. These activities that remove decadent willow and alder trees that constrict the river channel (see Background on Feather Edge projects). 

Cross Sections of the Trinity River

Cross sections can show changes in river bed elevation at a particular transect. This information is useful to determine if a stream bed is filling in as a result of excess sediment transport or whether it is in recovery and scouring back down after sediment inputs have been decreased. KRIS contains McBain and Trush cross section data measured at feather edge and side channel restoration sites and at other locations as part of their sediment transport studies. See McBain and Trush (1997) for more information. 

Water Temperature Monitoring

There now hundreds of water temperature datasets for Trinity River basin locations in KRIS Version 3.0. Data come from the Shasta Trinity National Forest, Six Rivers National Forest, Trinity County Resource Conservation District, Weaverville Natural Resource Conservation Service and private companies. The region-wide temperature data assimilation by the Institute for Forest and Watershed Management (IFWM) at Humboldt State University, formerly known as the Forest Science Project, aided data acquisition for Version 3.0 greatly. IFWM published an access database of  stream temperature monitoring data for the northern California coast (Lewis et al., 2000). The IFWM database includes 128 sites in the Trinity basin, with 15 in the Lower Trinity sub-basin, 42 in the Middle Trinity sub-basin, and 71 in the South Fork Trinity sub-basin. Descriptions of monitoring site locations for the Trinity Basin can be viewed as a table

The U.S. Fish and Wildlife Service Arcata Field Office has deployed automated temperature sensors throughout the Klamath and Trinity River watersheds, including the a number of stations along the mainstem Trinity. U.S. Fish and Wildlife Service has published numerous reports which utilize the water temperature data they collect (Guillien, 2003; Zedonis, 2003). Water temperature references used in KRIS are based on Pacific Northwest wide literature on salmonids and temperature (Armor, 1990; McCullough, 1999; Sullivan et al., 2000; Welsh, 2001). See the KRIS Temperature Background page for more information.

Bureau of Reclamation Photographs, Including Historical Aerials

Many photographs of the Trinity River Basin and restoration activities within KRIS have been provided by Russ Smith of the Bureau of Reclamation. Slides were transferred to CD and then processed in Photoshop for final preparation before entry into KRIS. Aerial photographs in KRIS were scanned from Bureau of Reclamation (BOR) and California Department of Water Resources (CDWR) 9" X 9" prints. Photo series are from June 8, 1961, January 17, 1974 and May 19, 1989 and are at a 1:6000 scale. The original 1974 and 1989 photographs belong to the BOR regional office at Shasta Dam, while the 1961 photos are at CDWR Red Bluff office.

Rainfall and Snowfall Data

Rainfall data for the Trinity River has been collected at numerous U.S. Forest Service Ranger Districts, by private parties or by the Bureau of Indian Affairs at Hoopa with some records extending back to 1861. Data in KRIS are from the CDEC. All Trinity River watershed gauges have been captured in the California Department of Water Resources report entitled: Monthly Precipitation Averages In or Near the Trinity River Drainage Area Based on or Corrected to the Period 1905-06 to 1954-55. Although the report by J.D. Goodridge had a date of December 3, 1959 it actually went to press later and had actually been updated to 1962. This report is in the CDWR Northern District Office in Red Bluff. KRIS data on snowfall and more recent rainfall comes from the California Data Exchange Center web site. Snowfall data is often taken in varying months so comparisons in KRIS use only April values since it is the month for which values were most consistently available.
Below are the gauging stations for the main Trinity River area from Goodridge (1959).

LAT: 40 44 Elevation: 2050'
LONG: 122 56'
Observer: USFS
Station: Weaverville R.S.
Gauge Type: RRG & 8"
State No: F4 9490
Other No's: 40440-22560
WB 9490
Obtained from: C.D.

LAT: 40 52 Elevation: 650'
LONG: 123 35'
Observer: O.F. Westerburg
Station: Weaverville RS
CO: Trinity
Gauge Type: SRG
State No: F4 1731
Other No's: 40520-23350
Sec: 26
T: 6N
R: 5E
Obtained from: U.S.W.B. Climitological Data 12/15/52

LAT: 40 53' Elevation: 623'
LONG: 123 35' Observer:USFS
Station: Salyer RS
CO: Trinity
Gauge Type: SRG
Detail: South 0.1 mile from Sayler P.O.
State No: F4 7698
Other No's: 40530-23350
WB 7698
Sec: 14
T: 6N
Obtained from:HB,CD

LAT: 41' 0 Elevation: 2295'
LONG: 122 41'
Observer: USFS
Station: Trinity Center RS
CO: Trinity
Gauge Type: RRG (8' off gnd)
Detail: 2 miles south PO State No: F4 9023
Other No's: 41000-22410
WB 7698
Sec: 5
T: 36N
R: 7E
Obtained from: C.D.

LAT: 40 45 Elevation: 1248'
LONG: 123 15'
Observer: U.S.F.S.
Station: Big Bar RS
CO: Trinity
Gauge Type: SRG
State No: F4 0738
Other No's: 40450-23150
Sec: 5
T: 33N
R: 12W
Obtained from: U.S.W.B. Climitological Data

LAT: 40 23' Elevation: 2340'
LONG: 123 20'
Observer: Blanche Eslick 11/1/56
Station: Forest Glen
CO: Trinity
Gauge Type: SRG
Exposure Date: 5/1/30
State No: F4 3130
Other No's: 40230-23200
Sec: 22
T: 18
R: 8E
Obtained from: U.S.W.B. Climitological

LAT: 40 49' 30"
LONG: 123 30' 10"
Elevation: 2200'
Observer: J.F. Ambrose Box 6, Burnt Ranch Station: Burnt Ranch 3 NW
CO: Trinity
Gauge Type: SRG
Exposure Date: 9/5/58
State No: F4 1212
Other No's:
Sec: 10
T: 5N
R: 6E
Obtained: From observer

LAT: 40 48.3'
LONG: 123 28.6'
Elevation: 359'
Observer: Office of Indian Affairs
Station: Hoopa
CO: Trinity
Gauge Type: RRG
Exposure Date: 2/6/1941
Detail: 0.5 miles ssw of Hoopa PO
State No: F4 4082
Other No's: 41030-23410
Sec: 25
T: 8N
R: 4E
Obtained: 1949-50, '50-'51, USWB Climitological Data

LAT: 41 11'
LONG: 123 43'
Elevation: 1700'
Observer: M.E. Lathrop & G.S. Garner
Station: Weitchpec 7 NNE
CO: Humboldt
Gauge Type: SRG
Exposure Date: 1/1/1910
State No: F3 9505
Other No's: 41110-23430
Sec: 2
T: 10N
R: 4E
Obtained: USWB Climitological Data