Redwood Creek – Progress Report on

Erosion Control Work 

and 

Sediment TMDL

Prepared for the participating landowners in the Redwood Creek watershed, the California 

Department of Fish and Game, and the Pacific Coast Fish, Wildlife and Wetlands 

Restoration Association

By Redwood National and State Parks.

June 20, 2011

Redwood Creek – Progress Report on

Erosion Control Work and Sediment TMDL

Prepared by:

Greg Bundros

Darci Short

June 20, 2011

This report was prepared for the participating landowners in the Redwood Creek watershed, the 

California Department of Fish and Game, and the Pacific Coast Fish, Wildlife and Wetlands 

Restoration Association by Redwood National and State Parks.

Bundros, G.J. and Short, D. 2011. Redwood Creek – Progress Report on Erosion Control Work and 

Sediment TMDL. Redwood National and State Parks report to the Pacific Coast Fish, 

Wildlife and Wetlands Restoration Association, unpublished, 84 pp.
Page intentionally left blank
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL i

EXECUTIVE SUMMARY

The Redwood Creek watershed, in north coastal California, has unique characteristics that 

significantly increase the likelihood for successful watershed restoration and recovery. Redwood 

Creek is a moderate sized watershed that supports anadromous salmonid species. It has a National 

and State Park in the lower third of the watershed and the upper two-thirds is 90 percent owned by 

just eight landowners who manage lands for timber and ranching. Cooperative partnerships have 

formed to improve conditions throughout the watershed.

Cooperative efforts to control and prevent erosion from logging roads in the upper Redwood Creek 

watershed (areas upstream of the park) started in earnest in 1996. Detailed road assessments 

identified potential erosion sites, estimated sediment yields and recommended treatments. 

Subsequent road treatments have been completed through cooperative erosion control projects, 

separate landowner projects and timber harvest plan road work. About 120 miles have been 

upgraded and about 61 miles have been decommissioned. Total funding for all cooperative erosion 

control projects in the upper watershed through 2009 was about $5.8 million. Landowners have 

contributed about 33% of the funds. 

Analysis of detailed volumetric data shows road treatments have reduced the potential sediment 

yield from logging roads in the upper watershed by about 531,000 cubic yards. This is about 30 

percent of the potential sediment yield estimated at assessed sites or about 19 percent of the 

estimated total for the upper watershed.

Completed work has reduced potential sediment loading by about 36 percent of the TMDL’s 

required 60 percent load reduction. However, 71 percent of the total reduction occurred in the 

lower watershed, on park lands, compared to a 29 percent reduction in the upper watershed, 

mostly private lands. While both represent significant reductions, more work is needed in the 

upper watershed to more fully distribute load reduction throughout the watershed. For watershed 

recovery, the work is necessary and achievable. 

The analyses presented in this report prioritize erosion control and prevention treatments based 

on work completed through 2009. Each analysis works at a different scale and provides 

prioritizations that can be used individually or in combination appropriate to the scale and 

objective of the erosion prevention project.

A Watershed Improvement Plan is presented that identifies road management practices that can 

protect aquatic and riparian habitats, and move the watershed closer to recovery and meeting the 

objectives of the Redwood Creek TMDL.
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL ii

ACKNOWLEDGEMENTS

The road assessments and treatment projects in Redwood Creek would not have been possible 

without the generous funding by California Department of Fish and Game SB 271 grants, California 

Propositions 50 and 84, California State Water Resources Control Board, 319(h) grants, U.S. Fish 

and Wildlife Service, Bureau of Land Management, National Park Service, Resources Legacy Fund 

Foundation, and private landowners.

The project would also not have been possible without private landowner cooperation. The private 

landowners in Redwood Creek are willing partners who have provided access to their lands, 

funding, opinions and perspectives, and an optimistic outlook for improved watershed conditions. 

It is our hope that the report information is used appropriately and private landowners in Redwood 

Creek are never penalized for their trusting cooperation.

This report was prepared for Mitch Farro of Pacific Coast Fish, Wildlife and Wetlands Restoration 

Association (PCFWWRA) by Redwood National and State Parks under a cooperative agreement. We 

are grateful to Mr. Farro for his leadership role in Redwood Creek, as the project would not have 

occurred without his leadership. Pacific Watershed Associates provided invaluable technical 

oversight, training and quality control during this work as a sub-contractor to PCFWWRA. We are 

extremely grateful to Randy Lew who provided consistent quality control. Most importantly, we 

acknowledge the field crews who worked so diligently under sometimes adverse field conditions. 

They are dedicated and highly skilled, and did an outstanding job.

Thanks to Randy Klein, Mary Ann Madej and Vicki Ozaki for synthesizing sediment load data for 

Redwood Creek and review of the TMDL discussion. We also thank Judy Wartella for her expertise 

completing many of the GIS analyses contained in the report.
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL iii

TABLE OF CONTENTS

EXECUTIVE SUMMARY ...........................................................................................................................................................i

ACKNOWLEDGEMENTS........................................................................................................................................................ ii

TABLE OF CONTENTS........................................................................................................................................................... iii

INTRODUCTION....................................................................................................................................................................... 1

BACKGROUND........................................................................................................................................................................... 2

Watershed Description.................................................................................................................................................... 2

Land Use................................................................................................................................................................................. 2

Roads....................................................................................................................................................................................... 2

Cooperative Erosion Control and Prevention Efforts ......................................................................................... 4

ACCOMPLISHMENTS OF THE COOPERATIVE EROSION CONTROL PROGRAM 1996-2009.................... 4

Road Assessments.............................................................................................................................................................. 4

Completed Road Treatments......................................................................................................................................... 5

Accomplishments and the Total Maximum Daily Load for Redwood Creek ............................................. 8

TMDL for Redwood Creek......................................................................................................................................... 8

Hillslope Numeric Targets and Progress Made Attaining the Targets..................................................11

Sediment Load Reduction 1998-2009................................................................................................................14

Long-Term Average Annual Sediment Loads and 10-Year Rolling Annual Average ......................16

Discussion ......................................................................................................................................................................16

CURRENT ROAD CONDITIONS.........................................................................................................................................20

Drivability and Maintenance Status .........................................................................................................................20

Potential Sediment Yield...............................................................................................................................................21

Fluvial erosion sites ...................................................................................................................................................22

Landslide sites..............................................................................................................................................................23
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL iv

Estimated Costs for Treating Remaining Roads..................................................................................................24

TREATMENT PRIORITIES..................................................................................................................................................25

Prioritizing Roads and Sub-Watersheds Using Database Queries...............................................................25

Roads................................................................................................................................................................................26

Sub-watersheds ...........................................................................................................................................................27

Prioritizing Areas within the Watershed Using a GIS Spatial Analysis......................................................29

Prioritizing Sub-Watersheds Using Risk Analyses .............................................................................................29

Resource Threat..........................................................................................................................................................29

Resource threat and resource at risk..................................................................................................................34

Critical Crossings..............................................................................................................................................................34

WATERSHED IMPROVEMENT PLAN.............................................................................................................................39

CONCLUSIONS.........................................................................................................................................................................43

REFERENCES...........................................................................................................................................................................46

GLOSSARY.................................................................................................................................................................................49
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL v

Appendixes

Appendix A: Average road density by sub-watershed and interfluve

Appendix B: Field form used by RNSP and PCFWWRA

Appendix C: Redwood Creek road assessment site maps

Appendix D: Projects and grant funding

Appendix E: Methods used to estimate TMDL load reductions

Appendix F: Ranking criteria for assessed roads

Table F-1. Roads ranked by potential sediment yield.

Table F-2. Roads ranked by potential sediment yield per mile.

Table F-3. Roads ranked by cost-effectiveness.

Appendix G: Sub-watershed ranking with weighting values for risk analysis

Table G-1. Sub-watersheds ranked by total potential sediment yield. 

Table G-2. Sub-watersheds ranked by number of critical crossings in each subwatershed.

Table G-3. Sub-watersheds ranked by the number of Shalstab sites in each subwatershed.

Appendix H: Salmonid distribution in the Redwood Creek watershed

Figure H-1. Salmonid distribution in the Redwood Creek watershed.
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL vi

List of Figures

Figure 1. Location of the Redwood Creek watershed and road assessment areas. .....................................3

Figure 2. Reduction of potential sediment yield by decommission and upgrade treatments in upper 

Redwood Creek. ....................................................................................................................................................7

Figure 3. Treatment priorities based on threat and resource at risk, 2004....................................................9

Figure 4. Reduction in potential sediment yield, 2009.........................................................................................10

Figure 5. Total annual sediment loads for Redwood Creek, 10-year rolling annual average and 

TMDL target......................................................................................................................................................... 17

Figure 6. Annual sediment ‘savings’, TMDL target, and average annual sediment load in Redwood 

Creek 1998-2009............................................................................................................................................... 18

Figure 7. Cumulative annual sediment load (Qtl) at Orick with and without ‘savings’ from erosion 

control and prevention efforts 1998-2009.............................................................................................19

Figure 8. Potential sediment yield density................................................................................................................. 31

Figure 9. Sub-watershed ranking based on threat. ................................................................................................32

Figure 10. Resource threat and resource at risk. .....................................................................................................35

Figure 11. Critical crossing density............................................................................................................................... 37
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL vii

List of Tables

Table 1. Road assessments in the upper Redwood Creek watershed. ..............................................................5

Table 2. Sites treated and sediment saved for projects assessed by RNSP and PCFWWRA. ...................6

Table 3: Sediment ‘saved’ from delivery from fluvial and landslide sites. .....................................................7

Table 4. Summary of stream crossings, crossings with diversion potential and critical crossings. .....8

Table 5. Treated roads and hillslope position. ......................................................................................................... 12

Table 6. Controllable loads and reductions, Redwood Creek, 1998-2009. ..................................................15

Table 7. Average annual sediment loads at Orick gage for selected time periods. ...................................16

Table 8. Projects and data used in summary statistics and analysis for remaining (not 

decommissioned) roads. ..................................................................................................................................20

Table 9. Drivability of all assessed roads through 2009. .....................................................................................21

Table 10. Maintenance status of all assessed roads through 2009..................................................................21

Table 11. Potential sediment yield for remaining (not decommissioned) sites assessed by 

PCFWWRA and RNSP with proposed treatments. ..............................................................................22

Table 12. Selected information for fluvial erosion sites.......................................................................................23

Table 13. Class I stream crossings with medium or higher urgency...............................................................23

Table 14. Selected information for landslide sites. ...............................................................................................24

Table 15. Estimated treatment costs for roads not yet treated and extended to all roads....................25

Table 16. Treatment priority for roads based on potential sediment yield, yield per mile and/or

treatment cost-effectiveness......................................................................................................................... 26

Table 17. Sub-watershed treatment priority based on potential sediment yield per mile of road....28

Table 18. Sub-watershed treatment priority based on resource threat. ......................................................33

Table 19. Sub-watershed treatment priority based on resource threat and resource at risk. ............36

Table 20. Sub-watersheds and interfluves affected by state Highway 299. ................................................42
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 1

INTRODUCTION

The Redwood Creek watershed is unique from other north coastal California watersheds. It is 

relatively small (180,000 acres) and a national and state park occupies the lower-third of the 

watershed. Most of the land upstream of the park is used for forest products and ranching, and is 

owned by a relatively small number of large landowners which makes watershed-scale planning 

feasible. The Redwood Creek Watershed Group whose membership represents about 90 percent of 

the ownership and/or management of land in the watershed formed to improve water quality 

conditions throughout the watershed (RCWG, 2006). There are no major water diversions in the

watershed, and the only developed municipality is the town of Orick, located along the lowermost 

reach of Redwood Creek. These attributes significantly increase the likelihood that recovery and 

restoration efforts in Redwood Creek can succeed.

Studies performed in Redwood Creek have documented that erosion and sedimentation from past 

floods impact the channel for decades (Madej and Ozaki, 2009) and affect many life cycles of 

anadromous salmonids. Erosion from logging roads has been identified as the largest controllable 

source of sediment in the watershed (RNSP, 1997; USEPA, 1998). The sediment TMDL for 

Redwood Creek (USEPA, 1998), the Recovery Strategy for California Coho Salmon (CDFG, 2004), the 

Redwood Creek Watershed Assessment Report (Cannata et al., 2006), the Redwood National and 

State Parks (RNSP) General Management Plan/General Plan (NPS-CDPR, 1999), and the Integrated 

Watershed Strategy for Redwood Creek (RCWG, 2006) all encourage completion of road 

assessments, and implementation of road decommission and upgrade projects to protect and 

restore aquatic and riparian habitat and water quality. In Redwood Creek, cooperative efforts to 

control and prevent erosion from logging roads on private lands started in 1996.

This report is an update to previous reports that summarized road assessment data collected in the 

upper Redwood Creek watershed and described treatment priorities based on analysis of the data. 

In this update, we: 1) describe the accomplishments of the erosion control work since cooperative

efforts began and place the accomplishments in the context of the Redwood Creek sediment TMDL; 

2) summarize the conditions of the remaining assessed roads in the upper watershed, and; 3) 

present updated treatment priorities for areas in the upper watershed based on work that has been 

completed through 2009. Similar to previous reports, a watershed improvement plan is also 

presented. The erosion control work described in this report includes projects completed through 

cooperative efforts, completed timber harvest plans and individual landowner projects for which 

we have data.
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 2

BACKGROUND

WATERSHED DESCRIPTION

Redwood Creek drains a 285 square mile watershed located in the Coast Range of northern 

California (Figure 1). The upstream two-thirds of the watershed is mostly private lands managed 

for timber production and ranching. Redwood National and State Parks occupies the lower-third of 

the watershed. 

The watershed is steep and mountainous, and located within a tectonically active area with 

relatively rapid uplift. Weak, pervasively sheared rocks underlie the watershed. Mean annual 

watershed-wide precipitation averages about 80 inches. The combination of steep terrain, weak 

underlying geology and soils, and moderately high precipitation contribute to naturally high 

erosion rates and susceptibility to accelerated erosion.

The watershed is unusually long and narrow, and has a very large number of small tributary subwatersheds. There are no major tributaries to Redwood Creek above Prairie Creek. Most

tributaries are low-order and high gradient streams. Their channels are generally deeply incised, 

and steep hillslopes adjacent to channels are particularly landslide prone (Pitlick, 1982).

LAND USE

The primary land use in the watershed during the past 80 years has been timber production and 

ranching. Historically, roughly 82 percent of the Redwood Creek watershed supported old-growth 

coniferous forests. Harvesting of the coastal redwood forests in portions of the lower Redwood 

Creek watershed began in the latter half of the 1800s. Mechanized timber harvesting was 

established throughout the watershed by the late 1930s. Timber harvesting and associated road 

construction accelerated in the watershed in the late 1940s to 1950s in the Douglas-fir dominated

upper watershed. During the 1960s timber harvest was concentrated more in the lower watershed, 

and logging continued steadily until expansion of Redwood National Park in 1978. By 1978, about 

81 percent of the original forest in the watershed had been logged (Best, 1984).

ROADS

The earliest roads in the Redwood Creek watershed coincided with settlement in the mid-1800s. 

New roads were built as settlement and ranching expanded. A rapid rise in road construction 

occurred along with increased timber harvest in the mid-1900s. The road construction history for 

the Redwood Creek watershed was researched by RNSP and is described by Bundros et al. (2003).

The history of forest practice rules partly explains the legacy road conditions in the watershed 

today. State regulation of timber harvest activities began in 1945, but was not fully implemented 

until the passage of the Z’berg-Nejedly Forest Practice Act of 1973. The first substantive erosion 
Klamath

River

Trinity

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Miles

Ma d

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Humboldt

Bay

Source: N:\GIS_Maps\user_maps\60_UBErosionPreventionRanking\2010 Update

Compiled: February, 2011

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California

STUDY

AREA

Road Assessments

Roads Surveyed

Limited Data

Roads Unsurveyed
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 4

control rules for logging roads appeared in 1983. By then, more than 1,000 miles of roads in the 

upper watershed had been built to inadequate standards. More than 88 percent of the roads in 

existence today were built before forest practice rules had been fully implemented. Today, there

are about 1,040 miles of roads in the upper watershed of which about 907 miles are privately 

owned and managed. Road density averages 6.4 miles/mile2 and ranges from 3.6 to 10.7

miles/mile2 in tributary watersheds. The road density for all sub-watersheds is shown in 

Appendix A.

COOPERATIVE EROSION CONTROL AND PREVENTION EFFORTS

Cooperative efforts to control and prevent erosion from logging roads in upper Redwood Creek 

(areas upstream of the park) started in earnest in 1996. These efforts were built on trust. A small 

pilot project in 1995 was completed by RNSP and Green Diamond Resource Company (GDRCo -

formerly Simpson Timber Company) in Coyote Creek. In 1996 and in cooperation with the Stover 

family, RNSP completed the first large assessment and implementation project in Garrett Creek. 

This was followed by a larger assessment completed by RNSP and multiple implementation 

projects on Sierra Pacific Industries lands. The success of these earlier projects led to a partnership 

between numerous landowners, RNSP and Pacific Coast Fish, Wildlife and Wetland Restoration 

Association (PCFWWRA) to advance cooperative erosion control efforts in the upper watershed.

The cooperative erosion control efforts in Redwood Creek would not have been possible without 

agency grants and landowner funding. The U.S. Fish and Wildlife Service, Jobs-in-the-Woods 

program, provided grant funds during the development of this cooperative program. The California 

Department of Fish and Game’s (CDFG) Fisheries Restoration Grant program provided funding for 

subsequent assessments and implementation projects. Landowners have provided access, funding 

and support for all of the efforts described in this report.

Data from the initial road assessments completed in Redwood Creek were summarized in previous 

reports (Bundros et al., 2003; Bundros et al., 2004; Bundros and Short, 2009). Bundros et al.

(2003) also contains detailed discussions on road construction history, road density, timber harvest 

in the inner gorges along Redwood Creek and landslide history, channel erosion and riparian 

conditions and restoration opportunities.

ACCOMPLISHMENTS OF THE COOPERATIVE EROSION

CONTROL PROGRAM 1996-2009

ROAD ASSESSMENTS

Road assessment projects were developed with willing landowners and implemented as funding 

became available. Eleven distinct assessment projects, shaped by watershed boundaries, willing 

landowners and grant opportunities have been implemented by four different investigators – RNSP,
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 5

PCFWWRA, Natural Resources Management Corporation (NRM) and Five Counties Salmonid 

Conservation Program (SCP). Quality control for road assessments completed by PCFWWRA was 

provided by Pacific Watershed Associates and RNSP. Of the 1,100 miles of road existing in the 

upper watershed at the beginning of the program, about 773 miles (70 percent) have been 

assessed. The remaining 328 miles of roads are owned by landowners who have not participated in 

the cooperative erosion control efforts. 

All road assessments included field work that identified potential erosion sites, estimated the 

volume of sediment that could deliver to a stream if erosion occurred, and prescribed corrective 

treatments. All sites assessed by PCFWWRA also included cost estimates for equipment and labor 

needs. Data were compiled on field forms (Appendix B) and sites located on airphoto mylar 

overlays. All field data were entered into a database and the location of each site was entered into 

GIS as a point coverage (Appendix C). Both database and GIS coverages are maintained by RNSP. 

Table 1 describes the road assessments in upper Redwood Creek.

Table 1. Road assessments in the upper Redwood Creek watershed.

Road Assessments

(miles)

% of Beginning 

Length

 PCFWWRA Assessed 567 51%

 RNSP Assessed 93 8%

 NRM Assessed 88 8%

 Five Counties SCP Assessed 25 2%

Total Assessed 773 70%

Not Assessed 328 30%

Total Miles 1,101 100%

1

 Mileages shown differ from those reported in previous reports due to: Reassessment of Minor Creek by 

PCFWWRA ‘replacing’ the roads assessed by NRM, new road construction associated with THPs, assessment of 

roads subsequent to previous assessments and, to a lesser extent, clean-up/editing of minor GIS errors. 2

 Totals may differ slightly from those shown in other tables in this report due to rounding.

In all road assessments, investigators followed generally similar methods to collect and record 

information. However, subsequent data analysis revealed inconsistencies between some 

investigators which prevented the use of data collected by NRM and Five Counties SCP in most of 

the analyses in this report.

COMPLETED ROAD TREATMENTS

Projects to control and prevent potential erosion identified by road assessments in the upper 

watershed have been implemented since 1996. As assessments were completed in specific areas, 

projects were implemented soon afterward to treat the obvious high priority roads and sites. 

Projects were implemented where assessments were completed while further assessments were 

occurring in other areas. After most of the assessments had been completed, treatment priorities 

for areas in the upper watershed were based on results from analyses reported by Bundros et al. 

(2003 and 2004).
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 6

Roads have been treated through cooperative erosion control projects, separate landowner projects 

and timber harvest plan (THP) road work. RNSP has reviewed all reports of cooperative projects 

completed from 1996 through 2009 and all CDF approved THPs within assessment areas through 

2007. Most treated roads have been field reviewed by RNSP geologists to evaluate completed 

treatments. Some decommissioned roads were not field reviewed by RNSP, but were described in 

project completion reports prepared by Pacific Watershed Associates. BLM geologists provided 

similar reports and data for work completed in Lacks Creek.

Of the approximately 660 miles of roads assessed by PCFWWRA and RNSP, about 181 miles have 

been treated since 1996. About 120 miles have been upgraded and about 61 miles have been 

decommissioned. Total funding for all cooperative erosion control projects in the upper watershed 

through 2009 was about $5.8 million. Landowners provided about $1.9 million (33%) in funding 

with the remainder provided by various grant sources totaling about $3.8 million (67%). Costs 

associated with work completed independently by landowners and in association with THPs are 

not included. A list of projects and funding is included in Appendix D.

Table 2 shows selected statistics for sites that have been treated. Of the 4,955 sites assessed 

between 1996 and 2009, 1,090 sites (22 percent) have been treated. More than 13 percent of all 

assessed sites were decommissioned and about 9 percent of all assessed sites were upgraded. 

Combined, the sediment “saved” (the potential sediment yield prevented from entering a stream) 

by all treatments was over 531,000 yds3. Figure 2 shows these data graphically.

Table 2. Sites treated and sediment saved for projects assessed by RNSP and PCFWWRA.

No. of 

Sites

Potential 

Sediment 

Yield 

(yds3)

% 

Number

of all 

Sites

% of 

Potential 

Sediment 

Yield

Sites in Initial Assessments (1996 – 2009) 4,955 1,765,000 100% 100%

Sediment Saved from Delivery

 Decommissioned Sites 660 414,000 13% 23%

 Upgraded Sites 423 117,000 9% 7%

 Maintained Sites 7 0 0% 0%

Totals 1,090 531,000 22% 30%

 Sites Treated under THPs 177 39,000 4% 2%

 Sites Treated under Cooperative Erosion Control Program 913 492,000 18% 28%

 New Sites Treated, Not in Initial Road Assessments 146 Not avail. 3% Not applic.

 Totals 1,236 531,000 25% 30%

1

 All THPs filed through 2007, all cooperative projects through 2009.
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 7

Figure 2. Reduction of potential sediment yield by decommission and upgrade treatments in upper 

Redwood Creek.

Further breakdown of the 1,090 treated sites show that about 76 percent of the sites were fluvial 

and about 24 percent were landslide sites. The fluvial sites accounted for about 48 percent of the 

volume ‘saved’ (prevented from delivery to a stream), while landslide sites accounted for 52 

percent. Table 3 shows the sediment saved from fluvial and landslide sites that were in the initial 

road assessments.

Table 3: Sediment ‘saved’ from delivery from fluvial and landslide sites. 

(Includes decommission and upgrade treatments.)

Site type Count

Sediment 

‘Saved’ from 

Delivery

% of Count of 

all of Sites 

Treated

% of Potential 

Sediment Yield 

‘Saved’

All Sites Treated and in Initial Road 

Assessments 1,090 531,000 100% 100%

Fluvial Sites 833 257,000 76% 48%

 Stream Crossings 542 237,000 50% 45%

 Other Fluvial Sites 291 20,000 27% 4%

Landslide Sites 257 274,000 24% 52%

The initial assessments by RNSP and PCFWWRA included 2,540 stream crossing. Of those, 1,590

(63%) had a diversion potential. Of all stream crossings, 464 (18%) were ‘critical’ crossings

(stream crossings with an undersized culvert, diversion potential and at least a medium plug 

potential). Treatments, either decommission or upgrade, have corrected 340 diversion potentials 

and 110 critical crossings. These statistics are summarized in Table 4.
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 8

Table 4. Summary of stream crossings, crossings with diversion potential and critical crossings.

Type of Stream Crossing Number of Sites in 

Initial Assessments

% of all

Sites

Number of 

Sites Treated

% of Type 

Treated

Stream Crossings 2,540 100% 540 21%

 w/ Diversion Potential 1,590 63% 340 21%

 Critical Crossings 464 18% 110 24%

Another way to look at treatment accomplishments is spatially. Figure 3 shows the treatment 

priorities reported by Bundros et al. in 2004 that assigned treatment priorities to the subwatersheds in upper Redwood Creek. Priorities were based on a risk analysis that considered 

sediment, as the resource threat, and salmonids, as the resource at risk. Figure 4 shows that the 

greatest reduction of potential sediment yield has occurred in the areas where the treatment 

priorities were the highest in that analysis.

ACCOMPLISHMENTS AND THE TOTAL MAXIMUM DAILY LOAD FOR REDWOOD CREEK

This section places the erosion control and prevention work completed between 1998 and 2009 in 

the Redwood Creek watershed in context with the Total Maximum Daily Load (TMDL) for Redwood 

Creek. We attempt to answer the question, “To what extent has the road work completed 

throughout the watershed in the past 12 years met the objectives identified by the TMDL?” RNSP 

started decommissioning roads in the lower watershed in 1978 and cooperative erosion control 

and prevention work in the upper watershed (areas upstream of the park) started in 1996, before 

TMDL discussions began.

TMDL FOR REDWOOD CREEK

The sediment TMDL for the Redwood Creek watershed was developed primarily to promote 

activities that protect aquatic and riparian habitats and water quality from sedimentation 

associated with land use. Accelerated erosion from the combined effects of past land use practices 

and large storms impacted the migration, spawning, reproduction, and early development of 

anadromous fish such as coho salmon, Chinook salmon, and steelhead trout (EPA, 1998). The 

TMDL identified logging roads as the major source of controllable sediment.

Based on long-term annual sediment load records for Redwood Creek, the TMDL estimated the 

total annual sediment loading at about 4,750 tons per square mile per year. The total allowable 

sediment load, or TMDL, was estimated at 1,900 tons per square mile per year, a 60 percent 

reduction in total sediment loading. To allow for temporal variation, the allowable load was 

expressed as a 10-year rolling annual average.

The TMDL identifies both instream and hillslope numeric targets. Instream targets are meant to 

provide a measure of the quality of aquatic habitat and whether or not streams are recovering from 

sediment impacts associated with management activities. The TMDL envisions a monitoring 

program that would evaluate the instream targets through time. To our knowledge, such a 

monitoring program does not exist. In contrast, hillslope targets describe the desired condition for 

the watershed with respect to management activities that can affect sedimentation and water 
June

Debris Torrent

Lacks

Minor

Bridge

Coyote

Devils

Noisy

Panther

Lupton

Minon

Garrett

High Prairie

Pardee Bradford

Toss-Up

Lake Prairie

Dolly Varden

Captain

Windy

Emmy Lou

Simon

Gunrack

Pilchuck

Garcia

Headwaters_M

Upper Panther

Wiregrass

Moon

Loin

Last Gap

Squirrel Tail

George

Sweathouse

Cashmere

Stover

Six Rivers

Twin Lakes

Snow Camp

Joplin

Cool Springs

Lee

Santa Fe

Lineament

Marquette

Tom

Fern Prairie

Jena Cut-Off Meander

Ayers

Burley

Smokehouse

Greenpoint

Christmas Prairie

Johnson Prairie

Monroe Flat

Headwaters_W

Headwaters_E

Powerline

Timbo

Sub-watershed Ranking Based 

on Resource Threat and 

Resource at Risk

Upper Redwood Creek Watershed

Source: RNSP GIS - N:\GIS_Maps\user_maps\60_UBErosionPreventionRanking\Feb2004Updates

Compiled: February, 2004

*This map shows the result of a numerical risk analysis that is

based on resource threat and resource at risk (anadromous 

salmonids). Sub-watersheds are ranked only if at least 40% of 

the roads in the sub-watershed were assessed.

0 1.25 2.5 5 7.5 10

Miles

Sub-watershed Ranking*

Very High

High

Medium

Low

Very Low

Not Ranked

Status of Inventory Data

Limited Data

Currently Unsurveyed

Park lands

Streams (1:24k)

Watershed divides
Lacks

Minor

Garrett

Stover

Bradford

Coyote

Johnson Prairie

Molasses

Devils

Panther

George

Dolly Varden

Lee

Garcia

Cashmere

Pilchuck

Toss-Up

Sweathouse

Captain

Negro Joe

Windy

Squirrel Tail

Emmy Lou

Cut-Off Meander

Gunrack

Simon

Minon

June

Wiregrass

Loin

Santa Fe

Greenpoint

Lupton

Fern Prairie

Christmas Prairie

Jena

Noisy

Cool Springs

Six Rivers

Upper Panther

Last Gap

Lineament

Headwaters_E

Headwaters_M

High Prairie

Lake Prairie

Pardee

Marquette

Timbo

Powerline

Snow Camp

Smokehouse

Twin Lakes

Burley

Tom

Headwaters_W

Debris Torrent

Ayers

Beaver

Source: RNSP GIS - N:\GIS_Maps\user_maps\60_UBErosionPreventionRanking\2010 Updates

Compiled: February, 2011

0 1 2 4 6 8

Miles

Reduction in Potential Sediment

Yield 1996 - 2009

Upper Redwood Creek Watershed

*This map shows where the greatest reduction in potential

sediment yield has occurred in the upper watershed for the

period of 1996 through 2009. The analysis used all sites that

had or still have at least a medium erosion potential. Potential

sediment yield is considered for each sub-watershed and

interfluve area. Areas of limited data were not used in this analysis.

Reduction in

Potential Sediment

Yield (yds)*

60,000 - 80,000

40,000 - 60,000

20,000 - 40,000

10,000 - 20,000

< 10,000

No Change

Status of Inventory Data

Limited Data

Currently Unsurveyed

Park lands

Streams (1:24k)

Watershed divides
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 11

quality. Hillslope targets address the disconnect between the timing of improved hillslope 

conditions and channel recovery, and separate legacy channel effects from current hillslope 

conditions. Hillslope targets are also measureable and their improvements are immediate. The 

EPA believed that meeting hillslope targets would allow watershed recovery and attainment of 

instream targets through time. 

The following discussion focuses on the hillslope numeric targets because they relate directly to the 

erosion control and prevention work performed in the Redwood Creek watershed. Because many 

of the roads in the lower watershed, on park lands, had already been treated by 1998, the primary 

focus of the discussion will be on the work completed in the upper watershed, mostly private lands 

and for which we have data. Additional information about the Redwood Creek TMDL can be found 

in Appendix E.

HILLSLOPE NUMERIC TARGETS AND PROGRESS MADE ATTAINING THE TARGETS

The hillslope numeric targets in the TMDL describe the desired conditions with respect to road 

design, location, inspection and maintenance, and timber harvest practices in sensitive streamside 

areas. The following describes to what extent the hillslope targets have been met in the upper 

watershed through cooperative erosion control and prevention work, independent landowner 

projects or through completed timber harvest plans. The hillslope targets are listed individually, 

followed by a description of the accomplishments and a brief discussion that integrates the targets 

and accomplishments:

Target: No crossings have a diversion potential (i.e., crossings are reconfigured permanently 

to prevent stream diversion).

Accomplishments: The number of stream crossings with diversion potential has been reduced by 

21 percent on assessed roads. Initial assessments identified about 2,540 stream crossings of which 

about 1,590 (63%) had a diversion potential. Subsequently, about 340 have been either 

decommissioned or upgraded. Because 270 stream crossings were decommissioned, there are now 

about 2,270 crossings remaining in the assessment areas, of which 1,250 (56%) have a diversion 

potential.

These results can be extended to the unassessed roads in the upper watershed. The initial 

assessments identified about 2.4 crossings with diversion potential per mile of road. By applying 

this average density to all unassessed roads, we estimate there were about 2,650 stream crossings 

with diversion potential in the entire upper watershed prior to treatments. When the 340 treated 

crossings are considered, the number of stream crossings with diversion potential in the upper 

watershed has been reduced by about 13 percent since cooperative erosion control began in 1996.

Discussion: Progress has been made preventing stream diversions, but more work needs to be 

done. Language that acknowledges the sediment threat to water quality from stream diversion 

erosion has been in the state forest practice rules since 1983. The rules, however, have often relied 

on the maintenance of structures, such as waterbars, to prevent diversions rather than requiring 

construction of more permanent, maintenance-free structures such as dips. Since maintenance 

requirements expire one to three years after completion of a timber harvest plan, temporary 
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 12

structures eventually break down and become ineffective. Rules and enforcement of measures that 

prevent stream diversions have improved in recent years. New road rules under consideration at 

the time of this writing may finally address this critical issue (CDF, 2011).

Target: All culverts and crossings are sized to pass the 50-year flood and associated sediment 

and debris. Crossings and culverts in the snow zone (generally, upstream of Highway 299) are 

sized large enough to accommodate flows and associated sediment and debris caused by 

rainfall and snow melt runoff.

Accomplishments: The number of crossings capable of passing a 50-year flood in the assessment 

areas increased by about 22 percent. The improvement occurred by decommissioning and 

upgrading roads. Of the remaining crossings in the assessment areas, 43 percent of the culverted 

crossings will pass a 50-year flood, meeting the TMDL hillslope target, and 37 percent will pass a 

100-year flood, the current sizing standard in state forest practice rules. 

Discussion: Stream crossing culvert sizing requirements and methods have markedly improved. 

State forest practice rules changed culvert sizing requirements for stream crossings from a 50-year 

flood to a 100-year flood in 2001 (CDF, 2001). Guidance documents prepared by the California 

Department of Forestry and Fire Protection describe proper culvert sizing methods and 

considerations for passage of flood flows, including sediment and debris (Cafferata et al., 2004). 

Target: All landings and road fills on slopes >50% which could potentially deliver sediment to 

a stream are pulled back and stabilized.

Accomplishments: Based on GIS analysis of assessed sites with at least a medium treatment 

urgency, 43 percent of the sites on slopes greater than 50 percent were treated. When 

relationships from assessed roads that consider the number of sites per mile of road and the 

percentage of sites that occupy various slope categories are applied to the miles of unassessed

roads, about 31 percent of the sites on slopes greater than 50 percent were treated throughout the 

upper watershed.

Table 5 below classifies the road miles that have been treated by hillslope position. Hillslope 

position is based on an equal division of the hillslope area above a stream channel and is divided 

into three positions, including the upper-third, middle-third and lower-third.

Table 5. Treated roads and hillslope position.

Road Treatment Miles

% of Road Miles Treated Based

on Hillslope Position

Lower Middle Upper

Decommissioned 61 50% 38% 12%

Upgraded 123 28% 38% 34%

Discussion: Significant progress has been made treating landings, road fills and crossings on the 

steeper hillslope areas. Erosion control and prevention work in upper Redwood Creek has been 

guided by treatment priorities established through analyses of road assessment data (Bundros et 
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 13

al., 2003 and 2004). The treatment priorities considered, among other things, the proximity of 

roads to a stream channel and the likelihood of failure and sediment delivery. Generally, the 

steepest hillslope areas are found along streams and in the lowermost hillslope position. Results in 

Table 5 (above) are consistent with the GIS analysis of treated sites and slope steepness. The table 

shows that most of the decommissioned roads occupied lower hillslope positioned areas. In 

contrast, roads that have been upgraded tended to occupy the more gentle, mid- to upper- hillslope 

positions. Roads on gentler slopes are commonly used to access and treat the roads on steeper 

slopes, and they are nearly always treated too.

Target: All roads have surfacing and drainage facilities or structures which are appropriate 

to their patterns and intensity of use.

Accomplishments: The analysis of road assessment data cannot determine the degree to which this 

target is being met. 

Discussion: This target is affected primarily by land use regulations and, in general, we believe 

progress has been made in attaining this target. Provisions that address road surfacing, timing of 

road use and drainage facilities are found in multiple sections of the state forest practice rules. 

These measures were greatly improved with the implementation of the Threatened or Impaired 

Watershed rules in 2001 (CDF, 2001) and the Anadromous Salmonid Protection Rules (CDF, 2009). 

A good example of improved road management is Green Diamond Resource Company’s Aquatic 

Habitat Conservation Plan (GDRCo, 2006) which contains standards for road surfacing, timing of 

road use and drainage structures.

Target: All roads are inspected and maintained annually or decommissioned. 

Decommissioned roads are maintenance-free.

Accomplishments: Excluding roads that have been decommissioned, about 44 percent of all roads 

assessed are being maintained. About 10 percent of the roads assessed have been decommissioned 

and are maintenance-free. Including the decommissioned roads, about 54 percent of all roads 

assessed are being maintained or are maintenance-free, leaving 46 percent of the assessed roads 

unmaintained.

Discussion: In 2004, we reported that 32 percent of all roads assessed were being maintained 

(Bundros et al., 2004). The fact that 54 percent of the assessed roads are now being maintained (or 

are maintenance-free) is a substantial step towards reaching the TMDL target. It is possible that 

more roads are being maintained than we know about because work can occur without our 

knowledge. Road inspection and maintenance are affected more by land use regulations than by 

our cooperative erosion control and prevention program, but there are no regulations that require 

long-term annual road inspection and maintenance. Green Diamond Resource Company’s Aquatic 

Habitat Conservation Plan (GDRCo, 2006) contains explicit road inspection and maintenance 

standards for the 50-year life of the permit. Green Diamond Resource Company manages about 33 

percent of all roads in the upper watershed. The TMDL target would more likely be met if similar 

commitments were adopted throughout the watershed. Given the extensive road network in the 

upper watershed, it is unlikely the target will ever be met without significant incentives and effort. 
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 14

The enormous maintenance responsibilities for the roads in the upper watershed points to the need 

to: 1) decommission more roads in the upper watershed, and 2) make roads as maintenance-free 

as possible when they are in use and especially before THP inspection and maintenance 

requirements expire.

Target: Roads are not located in steep inner gorge or unstable headwall areas except where 

alternative road locations are unavailable.

Accomplishments: About 15 miles of roads have been decommissioned and 5 miles have been 

upgraded in the inner gorges of the upper watershed. Based on GIS analysis and excluding county 

and state roads, about 91 miles of inner gorge roads remain in the upper watershed. About 66 

miles of the remaining inner gorge roads have been assessed. Of these roads, about 20 miles (30%) 

are drivable and/or maintained; the balance are not drivable and/or maintained. We have no 

information on roads in unstable headwall areas.

Discussion: The vast majority of inner gorge roads were built before 1962. Current forest practice 

rules strongly discourage the construction or reconstruction of inner gorge roads. Based on the 

review of timber harvest plans submitted for Redwood Creek, no new inner gorge roads have been 

proposed for more than a decade. Residential subdivision and associated road construction may 

spawn construction of inner gorge roads without strong County oversight.

Target: Clearcut and/or tractor yarding are not used in steep, unstable streamside areas 

unless a detailed geological assessment is performed which shows there is no potential for 

increased sediment delivery as a result of using these methods.

Accomplishments: The analysis of road assessment data cannot determine the degree to which this 

target is being met. We have no information to address the metric requiring “no [emphasis added] 

potential for increased sediment”. 

Discussion: Improved forest practices have contributed significantly to attaining this TMDL target, 

because the rules now acknowledge the sensitivity of streamside areas to ground disturbance. The 

Report of the Scientific Review Panel on California Forest Practice Rules and Salmonid Habitat (Ligon 

et al., 1999) was a landmark study that, among other things, stressed the need for greater 

evaluation of steep streamside areas. As a result of this study and since 2001, state forest practice 

rules have required a detailed geologic assessment of proposed timber harvest operations on steep 

streamside areas, greater conifer retention in streamside areas and have discouraged tractor use in 

these areas (CDF, 2001). When harvest activities are proposed in potentially unstable streamside 

areas, findings from detailed geologic reports are reviewed during pre-harvest inspections by 

geologists from the California Geological Survey, the North Coast Regional Water Quality Control 

Board, and Redwood National and State Parks. The metric requiring “no [emphasis added] 

potential for increased sediment” is unlikely met by any ground disturbing activity.

SEDIMENT LOAD REDUCTION 1998-2009

The TMDL estimated that a 60 percent reduction in the long-term annual sediment load for 

Redwood Creek (4,750 tons/square mile/year) was needed for watershed recovery. Load 
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 15

reduction would be accomplished by treating controllable sources of sediment from roads as 

identified by the TMDL hillslope numeric targets. This section looks at how much of the 

controllable sediment load has been reduced throughout the watershed since 1998.

Controllable loads have been reduced by road decommissioning and upgrading projects. In the 

lower watershed, primarily park lands, an aggressive road decommissioning program has been 

underway since 1980. In the upper watershed, primarily private lands, roads have been 

decommissioned and upgraded through cooperative efforts, landowner projects and timber harvest 

activities since 1996. Properly decommissioned roads are maintenance-free and sediment sources 

are removed. In contrast, upgraded roads still contain potential sediment because the road is still 

in place, but the likelihood of failure during a large storm is low. 

In estimating the controllable load reductions (or sediment ‘saved’; i.e., the amount of sediment 

prevented from entering a stream by treating the road), the total volume of sediment treated 

through upgrades was also included, providing the corrective work met established standards, and 

the likelihood of site failure was low following treatment. Based on road assessment data for the 

upper watershed and records from the parks’ Watershed Restoration Program, Table 6 shows the 

reductions of controllable loads in the watershed since 1998.

Table 6. Controllable loads and reductions, Redwood Creek, 1998-2009 

(rounded to 1,000s).

Controllable Loads 

(tons) Load Reduction (sediment ‘saved’)

SubWatershed 1998 2009 Tons % by 

Sub-Wshd

% of 1998-2009 

Total Reduction

% of Total 1998 

Controllable Load

Lower 

Watershed 3,358,000 1,417,000 1,941,000 58% 71% 25%

Upper 

Watershed 4,289,000 3,511,000 796,000 19% 29% 10%

Totals 7,647,000 4,928,000 2,737,000 NA 100% 36%

Overall, controllable sources of sediment have been reduced by about 36 percent in the entire 

watershed, more than half the 60 percent reduction required by the TMDL. Most of the load 

reduction (71%) has occurred within the lower watershed where work has been reliably funded for 

a longer time. In the lower watershed, road decommissioning on park lands has treated about 58 

percent of the controllable loads in the lower watershed. In the upper watershed, road 

decommissioning and upgrade work has reduced watershed-wide controllable loads by about 29 

percent, or about 19 percent of the controllable loads in the upper watershed. Work on private 

lands has been funded by competitive grants and the landowners. Methods used to estimate load 

reductions are described in Appendix E
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 16

LONG-TERM AVERAGE ANNUAL SEDIMENT LOADS AND 10-YEAR ROLLING ANNUAL AVERAGE

The USGS operates a stream gaging station at Orick, about three miles upstream from the mouth of 

Redwood Creek. Stream discharge has been measured since 1954 and the total sediment load 

(suspended and bed load) has been measured since 1972. The more than six decade-long 

continuous record captures the variation in hydrologic conditions as well as the watershed’s 

response to land use and changing watershed conditions. Table 7 lists the average annual total 

sediment loads for Redwood Creek measured at Orick for selected time periods. The time periods 

were selected to show how the length of period considered and low to moderate flows can affect 

average annual sediment loads. 

Table 7. Average annual sediment loads at Orick gage for selected time periods.

Period Years Average Annual

Loads (tons/sqmi/yr) Comments

1954-2009 56 4,100 complete record (1954-1971 are synthesized data)

1954-1997 44 4,700 includes large storms; pre-TMDL

1990-2009 20 2,000 includes 1990s low flows and 1996-97 storms

1987-1993 7 870 low flow period

1998-2009 12 1,800 moderate flows during TMDL period

The EPA established the TMDL (allowable sediment load allocation) for Redwood Creek at 1,900 

tons/square mile/year expressed as a 10-year rolling annual average. The rolling average was 

meant to allow for variations in rainfall and runoff through time. Figure 5 shows the 10-year rolling 

annual sediment average for Redwood Creek from 1960 to 2009.

The total annual sediment load peaked in Redwood Creek by the early-1970s following periods of 

widespread sedimentation from the combined effects of early land use and large storms. Annual 

average sediment loads and the 10-year rolling average (plotted as the last year in a 10-year 

period) declined steadily for the next 20 years during a period of mostly low to moderate flows. 

During a period of low flows from 1987-1994, the 10-year rolling average fell below the TMDL 

target of 1,900 tons/square mile/year for the first time. The declining trend in the 10-year rolling 

average reversed following the storms in 1996 and 1997. Since 2007, the 10-year rolling average 

has once again dropped below the TMDL during a period of moderate flows.

DISCUSSION

Since the EPA established the TMDL in 1998, potential sediment loads have been reduced by about 

half of the required 60 percent load reduction at the watershed scale. But, the reduction has 

occurred to a greater extent by work completed in the lower watershed within park areas. Further 

reductions in controllable loads in the upper watershed are needed to more fully distribute load 

reduction efforts throughout the watershed. The 29 percent load reduction in the upper watershed 

was achieved by decommissioning and upgrading roads. Because upgraded roads are not 

maintenance-free, long-term maintenance of those roads will be critical to fully realize the benefits 

from the investments to reduce the potential for future road failures.
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 17

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

16,000

18,000

20,000

1960 1970 1980 1990 2000 2010

Sediment Load (tons/sqmi)

Water Year

TMDL target

10-year Rolling Ave.

Annual Sediment Load

Estimated Annual Sediment Load

Figure 5. Total annual sediment loads for Redwood Creek, 10-year rolling annual average and 

TMDL target.

The fact that the 10-year rolling annual average for sediment loads in Redwood Creek can fall below 

the TMDL target (1,900 tons/square mile/year) is very encouraging. We believe it shows the 

cumulative benefits and returns from erosion control and prevention efforts and improved land 

management practices. However, the 1996 and 1997 storms serve as reminders that more work 

needs to be done. Curry (HSU, 2007) reported that, in Redwood Creek and at the watershed scale, 

the storms were relatively moderate storms (12-year recurrence interval), but they triggered about 

250 landslides throughout the watershed that eroded more than 745,000 yds3 of material and 

reversed the declining trend of the 10-year rolling average curve. About 63 percent of the 

landslides were associated with roads (HSU, 2007). If large sediment inputs to Redwood Creek can 

be prevented during future large storms, sediment loads will drop as legacy sediment stored in the 

channel moves out of the system. Combined with cooperative efforts that decommission more 

roads, especially those in sensitive geomorphic settings, and upgrade and maintain the remaining 

road network, we believe the annual sediment loads will drop below the TMDL target and will be 

sustainable through the infrequent large storms.

There are about 1,040 miles of road in the upper Redwood Creek watershed and about 280 miles of 

road in the lower watershed. Road density in the upper watershed has fallen from about 7.2 

miles/square mile in 2004 to about 6.4 miles/square mile as of 2009. Road density in the lower 

watershed has fallen from about 4.9 miles/square mile in 1978 to about 2.4 miles/square mile. 

Both reductions are improvements, but we believe the road density in the upper watershed is still 

too high. At 6.4 miles/square mile, the road density in the upper watershed approximates the 
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 18

drainage density (7.5 miles/square mile) for all streams in the watershed. Thus, more roads need 

to be decommissioned in the upper watershed to reduce the sediment threats associated with 

roads.

When considering all work completed in the lower and upper watershed, the total amount of 

sediment ‘saved’ from 1998 to 2009 is approximately 2,737,000 tons, or about 9,900 tons per 

square mile of watershed area. This represents about 227,000 tons/year or 820 tons/square

mile/year. To put the sediment savings into perspective, the total sediment load for the same 

period in Redwood Creek was about 6,100,000 tons, or 22,000 tons/square mile, or 1,800 

tons/square mile/year. Because the amount of sediment reduction from erosion control efforts is 

not ‘realized’ in the same way as the annual sediment loads for Redwood Creek, it is difficult to 

make a direct comparison between the two. But, the fact that sediment reduction is about 46 

percent of the average annual load places a certain significance on the work accomplished. It will 

take large storms to test the effectiveness of the hillslope work and be able to observe the benefits 

from the completed work. 

Figure 6 shows the annual sediment ‘savings’ from work completed in the watershed from 1998 to 

2009. Also shown is the average annual sediment load for Redwood Creek for this same time 

period and the TMDL 10-year rolling average. While a direct comparison of sediment ‘saved’ to 

annual sediment transport rates is not possible because of the time delay in realizing the benefits of 

the work, showing this information together helps put the sediment ‘savings’ in perspective. As 

would be expected, the rate of work in the upper and lower watersheds varied, and years with no 

or minimal work coincided with a lack of project funding. Of the total sediment ‘saved’, about 29 

percent was saved from the upper watershed and 71 percent was saved from the lower watershed.

0

500

1,000

1,500

2,000

2,500

19981999

20002001

200220032004

20052006

20072008

2009

tons/sq.mi./yr.

UpperWshd

Lower Wshd

TMDL 10-year rolling average 1,900 tons/sq.mi./yr.

Average annual sediment load Redwood Creek 1,800 tons/sq.mi./yr.

Figure 6. Annual sediment ‘savings’, TMDL target, and average annual sediment load in Redwood 

Creek 1998-2009.
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 19

Figure 7 is another way to consider the benefits from the sediment savings from 1998 to 2009. It 

shows the cumulative annual sediment load for Redwood Creek measured at Orick and the savings 

from erosion control and prevention work. Sediment savings are shown along with both measured 

sediment loads and what the theoretical sediment loads might have been without these efforts. The 

plot shows that cumulative sediment loads would have increased by about 30 percent without 

completed erosion control and prevention treatments. The plot assumes the sediment ‘savings’ are 

immediate, which we know is unlikely. 

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

1996 1998 2000 2002 2004 2006 2008 2010

tons/sq.mi./yr.

Orick Qtl w/out Savings

Orick Qtl

Sediment Savings

Figure 7. Cumulative annual sediment load (Qtl) at Orick with and without ‘savings’ from erosion

control and prevention efforts 1998-2009.

The results presented in this section represent the minimum benefits from the completed work. In 

other words, it is important to remember that, through time, the sediment savings provide returns 

just like any investment: interest and dividends accrue and compound annually. And, as with 

investments, small increases in principle amounts add up to large returns through time. Water 

quality and salmonid habitat will likely improve at the sub-watershed level before the cumulative 

benefits combine to improve conditions in the main channel of Redwood Creek. Sediment 

reduction from erosion control and prevention efforts will create benefits such as clean water, 

increased pool depth and frequency, and stable riparian areas that support conifer growth for large 

woody debris recruitment and improved stream water temperatures. A less tangible but significant 

return on these investments are the offsite cumulative impacts that will be prevented by the 

competed work. 

Significant progress has been made toward attaining the TMDL hillslope targets in Redwood Creek, 

but more work needs to be done. Further reductions in controllable loads in the upper watershed 

are needed to more fully distribute load reduction efforts throughout the watershed. The rate of 

future work will depend on funding opportunities and global economic trends which affect the 
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 20

demand for lumber products. A more consistent and well-funded watershed-wide program would 

speed attainment of the TMDL targets and watershed recovery. The Park is committed to seeking 

funding opportunities in partnership with cooperators primarily to decommission roads.

CURRENT ROAD CONDITIONS

This section describes the current condition of the remaining assessed roads in upper Redwood 

Creek. Results are based on road assessment data which have been updated for each site and road 

that has been treated through either cooperative erosion control projects, separate landowner 

projects or THP road work

Throughout this discussion we use project data that are reliable for the specific summary statistic 

or analysis. During each assessment, some investigators recorded all data used in all tables and 

analyses in this report. Others did not record estimated treatment costs or used volumetric surveys 

that were inconsistent with most other assessments in the watershed. Table 8 shows the 

assessment projects, the total road miles for those projects and which data are used in summary 

statistics and analyses.

Table 8. Projects and data used in summary statistics and analysis for remaining (not 

decommissioned) roads.

Projects with Reliable Data Summary Statistic or Data Analysis

Total Road 

Miles

Assessed

% of Remaining

Roads in Upper 

Redwood Creek

PCFWWRA All cost tables and prioritizing roads 518 50%

PCFWWRA and RNSP Sediment yield and prioritizing roads

and areas 601 58%

PCFWWRA, RNSP, NRM

and County Drivability and maintenance status 712 68%

Not Assessed 328 32%

Total all Remaining Roads 1040

DRIVABILITY AND MAINTENANCE STATUS

Drivability and road maintenance status were documented during each assessment. The data were 

updated after completion of subsequent road treatments. Roads were described as drivable, not 

drivable, maintained, unmaintained, or decommissioned. Of the remaining (not decommissioned) 

712 miles of assessed roads, about 400 miles are considered drivable by a standard 4WD vehicle 

and about 257 miles are considered not drivable. Drivability was not documented for about 55

miles of roads. Drivability is summarized in Table 9.
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 21

Table 9. Drivability of all assessed roads through 2009.

Drivability Miles % of Total Assessed Miles

Drivable 400 56%

Not Drivable 257 36%

Not Documented 55 8%

Total Assessed Roads Remaining 712 100%

Maintained roads show signs of recent maintenance, such as cleaning of culvert inlets, trash racks, 

and inboard ditches; grading; rolling dip or water bar reconstruction; brushing; culvert 

replacement; or fill reconstruction. Unmaintained roads lack obvious maintenance to culverts and 

ditches, and vegetation encroaches on the road and road surface. The road may or may not be 

drivable. There are presently about 310 miles of maintained roads and about 330 miles of 

unmaintained roads. The status was not documented for about 72 miles of road. Table 10

summarizes these data.

Table 10. Maintenance status of all assessed roads through 2009.

Maintenance Status Miles % of Total

Assessed Miles

Maintained 310 44%

Unmaintained 330 46%

Unknown Status 72 10%

Total Assessed Roads Remaining 712 100%

POTENTIAL SEDIMENT YIELD

Potential sediment yield is the volume of sediment that can potentially erode and be delivered to a 

stream during a large storm. The volume is an estimate calculated from field measurements made 

of the void that would erode if a potential erosion site failed. In this report, potential sediment yield

is always the larger of site potential yield or the extreme potential yield (refer to the glossary for 

definitions) for each site (if one exists).

Initial road assessments by PCFWWRA and RNSP identified 4,955 sites as reported in Table 2. 

During subsequent road treatment projects, additional erosion sites were identified and assessed. 

The values reported below reflect all data from the initial road assessments and data from 129 

additional sites assessed during treatment projects.

A total of 5,084 sites were evaluated in the field since 1996 by PCFWWRA and RNSP. Of these, 737 

have been decommissioned and subsequently have negligible potential sediment yield. Of the 

remaining 4,347 sites, there are 3,528 fluvial erosion sites and 819 landslide sites. Potential 

sediment yield is summarized in Table 11.
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 22

Table 11. Potential sediment yield for remaining (not decommissioned) sites assessed by 

PCFWWRA and RNSP with proposed treatments.

No. of 

Sites

Erosion 

Volume 

(yds3

) 2

Site 

Potential 

Yield 

(yds3)

Extreme 

Potential 

Yield 3

 

(yds3)

Potential 

Sediment 

Yield 4

 

(yds3)

% of 

No. of 

Sites

% of 

Potential 

Sediment 

Yield

Sites Assessed and 

Remaining 1 4,347 1,697,600 985,000 468,800 1,270,000 100% 100%

All Sites with No Yield 569 8,600 0 0 0 13% 0%

All Sites, Yield >0 3,778 1,689,000 985,000 468,800 1,269,900 87% 100%

M-H Sites, Yield >0 1,942 1,015,800 637,900 366,000 865,400 45% 68%

All Fluvial Sites 3,528 712,300 708,100 112,000 768,000 81% 60%

All Landslide Sites 819 985,200 276,900 356,800 501,900 19% 40%

Field Call for Treatment

 Decommission 1,405 861,200 384,100 264,800 547,200 32% 43%

 Upgrade 2,016 759,500 528,600 175,000 627,100 46% 49%

 Maintain 895 74,800 70,600 25,000 90,600 21% 7%

 None 31 2,100 1,700 4,000 5,100 1% 0%

Totals all Sites4 4,347 1,697,600 985,000 468,800 1,270,000 100% 100%

Table notes:

1 Number of sites differs from value shown in Table 2, because this table includes 129 additional sites assessed 

during treatment projects.

2 Erosion Volume is that amount of sediment that can potentially erode from a site. 3 329 out of 4,327 sites had an extreme potential yield. 4 Potential Sediment Yield is the greater of the site potential yield and the extreme potential yield for each site then 

summed for all sites. It is not the sum of the two columns “Site Potential Yield” and “Extreme Potential Yield”.

5 Small differences in sums or with other tables are due to rounding.

FLUVIAL EROSION SITES

Of the remaining sites, not decommissioned, there are 3,528 fluvial erosion sites. Of those, 2,301

are haul road stream crossings. Of these, 1,218 have treatment urgencies of medium or higher with 

the potential to yield about 465,600 yds3 of sediment to streams. This is about 63 percent of the 

potential sediment yield of all medium and higher urgency fluvial erosion sites. Skid trail crossings 

account for the next largest volume of potential sediment yield with an estimated 14,200 yds3

possible sediment delivery from 78 sites with medium or higher treatment urgency. Selected data 

for fluvial erosion sites are shown in Table 12.
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 23

Table 12. Selected information for fluvial erosion sites.

Fluvial Features

All Urgency Sites Medium to High Urgency Sites

No. of 

Sites

Potential 

Sediment 

Yield

No. of 

Sites

Potential 

Sediment 

Yield

% of No. of 

Medium+

Sites

% of Pot. 

Sediment 

Yield

Haul road stream crossings 2,301 723,800 1,218 465,600 83% 61%

DRC1 with sediment delivery 358 10,400 111 5,100 8% 1%

DRC, no sediment delivery 463 0 0 0 0.0% 0.0%

DRC, road reaches 5 100 0 0 0.0% 0.0%

Road reach 142 5,700 53 3,300 4% 0%

Skid trail crossings 147 25,000 78 14,200 5% 2%

Swales 112 3,000 6 800 0% 0%

Totals 3,528 768,000 1,467 489,000 100% 64% 1 DRC – Ditch Relief Culvert

Fish passage at stream crossings –

There were 21 Class I stream crossings identified during road assessments. Subsequent to initial 

assessments, four sites were decommissioned, one upgraded and one found not treatable as part of 

an adjacent road decommissioning project. Of the 17 remaining sites, four sites have treatment 

urgencies of medium or higher. Table 13 shows the current status of these four Class I streams. 

One of the crossings shown is identified as a possible barrier to fish.

There are additional Class I stream crossings in Redwood Creek along roads managed by Humboldt 

County and Caltrans that are not reported here. Areas not assessed as part of the cooperative 

erosion control program are also not included in Table 13.

Table 13. Class I stream crossings with medium or higher urgency.

Site ID Road Name Location Type Urgency Comment

2064050 LC4000 Mainstem

Lacks

Washed 

out MED "King's Crossing” mostly washed-out. 

About 100 yds3 remain within mainstem.

4037223 Dolly 

Varden Cashmere Old log bridge

MEDHIGHFailing -bridge may be barrier. Need to 

replace or remove.

5038016 UPR-10 Mainstem 

Windy Bridge MEDHIGH

Bridge seriously constricting channel. 

Need to replace.~400 yards of pot. yield.

5044018 L2000-CN Noisy Bridge MED Bridge condition is OK. Road drainage 

treatments are medium urgency.

LANDSLIDE SITES

Of the remaining sites, not decommissioned, there are 819 assessed landslide sites. Of these, 477

sites have medium or higher treatment urgencies and potential sediment yield of about 376,400 

yds3. This is about 75 percent of total potential sediment yield from all landslide sites. Selected 

information for landslide sites is shown in Table 14.
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 24

Table 14. Selected information for landslide sites.

Landslide Features

All Urgency Sites Medium to High Urgency Sites

No. of 

Sites

Potential 

Sediment 

Yield

No. of 

Sites

Potential 

Sediment 

Yield

% of No. of 

Medium + 

Sites

% of Pot. 

Sediment 

Yield

Road 589 245,000 336 188,600 71% 38%

Landing 86 43,400 49 40,900 10% 8%

Hillslope 10 22,100 4 4,700 1% 1%

Road, Hillslope 64 114,300 35 76,800 5% 15%

Road, Landing 36 34,400 26 31,600 6% 6%

Road, Swale 25 23,500 21 21,100 7% 4%

Landing, Hillslope, Swale 9 19,200 4 12,700 0% 3%

Totals 819 501,900 477 376,400 100% 75%

ESTIMATED COSTS FOR TREATING REMAINING ROADS

Costs for treating all assessed sites and roads have been reported in past reports (Bundros et al.,

2003 and 2004; Bundros and Short, 2009) that estimated costs based on site specific information 

for equipment, material and labor needs using costs and rates in effect at the time of the reports. 

For this report, we used average treatment costs ($/mile of road to be treated) calculated in 2009 

from assessment data and applied those values to the remaining untreated roads in the upper 

watershed. We used this simplified method because the schedule for project implementation is 

uncertain and we know that costs, especially fuel costs, can vary significantly with time. Thus, the

cost estimates presented in this report are intended to provide only a general scale of funding 

needed to treat the remaining roads in the upper Redwood Creek watershed.

Table 15 lists the type of treatments prescribed by field crews, unit treatment costs and estimates 

to treat the remaining roads in the upper watershed. For the remaining assessed roads, cost 

estimates assume that all sites prescribed for decommission would be treated and only the upgrade

sites with urgency equal to or greater than medium would be treated. The final column in Table 15

extends the cost estimates to include all roads (not state or county owned) in the upper watershed

based on the per mile treatment cost for assessed roads and with the same ratio of decommissioned 

to upgraded roads. 

The estimated cost to treat the remaining 518 miles of assessed roads is about $24 million. When 

estimates are extended to include unassessed roads, the estimated total cost to treat all remaining 

untreated roads in the upper watershed is about $44 million. 
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 25

Table 15. Estimated treatment costs for roads not yet treated and extended to all roads.

Miles prescribed for 

treatment type:

Assessed roads Costs extended to

include all 

Data from previous reports unassessed roads

2003 2004 2009 2011 2011

Decommission (mi) 144 167 152 154 275

Upgrade (mi) 207 226 235 222 397

Maintain (mi) 83 95 76 142 151

Total (mi) 434 488 463 518 823

Average Cost per Mile 

Decommission $43,700 $42,8001 $72,700 $72,7002 $72,700

Average Cost per Mile 

Upgrade $36,300 $36,9001 $59,400 $59,4002 $59,400

Average Cost per Mile 

Maintain not avail not avail not avail not avail not avail

Total Cost to Treat 

Roads with Costs 

Assigned:

$13,815,000 $15,485,000 $24,950,000 $24,362,000 $43,588,000

Overall Average Cost 

per Mile $31,800 $31,800 $64,600 $53,000 $61,680

1 Fuel costs rose significantly between 2004 and 2009 affecting all costs. 2 Cost per mile for 2011 estimate based upon costs calculated in 2009.

TREATMENT PRIORITIES

This section presents examples of analyses that can be used to establish treatment priorities based 

on road assessment data. Each example analyzes road assessment data differently and at a 

different scale. Establishing priorities helps determine where the greatest benefits can be achieved 

and ensures limited funds are spent wisely. 

The analyses in this section have been presented in our previous summary reports (Bundros et al., 

2003 and 2004). Here, we repeat those analyses with consideration of all road treatments 

completed since cooperative erosion control efforts began. The results presented in this section 

reflect the new treatment priorities for the remaining assessed roads in the upper watershed.

PRIORITIZING ROADS AND SUB-WATERSHEDS USING DATABASE QUERIES

This analysis relies on database queries that characterize individual roads and sub-watersheds so 

that treatment priorities can be established. Unlike other analyses described in this section, 

database queries are based on treatment urgency instead of erosion potential.
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 26

ROADS

This analysis establishes a treatment priority for individual roads using database queries and data 

for sites assessed by PCFWWRA, and not decommissioned. Sites assessed by others were omitted 

because field crews did not prescribe detailed treatments nor estimate treatment costs. Roads that 

contained sites with medium to high treatment urgencies were ranked based on three criteria: 1) 

potential yield (volume of sediment that can enter a stream) from the entire road; 2) potential yield 

per mile of road evaluated, and; 3) treatment cost-effectiveness (the cost per cubic yard to prevent 

sediment from entering a stream). Road treatment priority was based on the ranking of each 

criterion for each road. Of the nearly 580 roads originally assessed, Table 16 lists, in alphabetical 

order, the 20 roads that have the highest treatment priority based on potential sediment yield, 

potential yield per mile of road and/or treatment cost-effectiveness when the top 30 roads (5%) of 

each criterion was considered. Tables F-1, F-2, and E-3 (Appendix F) show how each road ranked

for each criterion.

Table 16. Treatment priority for roads based on potential sediment yield, yield per mile and/or 

treatment cost-effectiveness. (The four roads with bolded names rank high in all three criteria.)

Road Name Length 

(mi)

Total 

no. of 

sites

Total no.

M to H 

sites

Potential 

Sediment 

Yield 

all sites 

(yds3

)

For Medium to High Urgency Sites

Potential 

Sediment 

Yield

(yds3

)

Potential 

Sediment 

Yield per 

mile 

(yds3 / mi)

Cost/yard

"saved" Total Cost

809 1.8 15 13 16,032 12,510 7,032 $12.53 $156,745

831 2.1 13 7 7,699 7,338 3,578 $2.02 $14,821

1140 0.8 15 7 12,616 7,144 9,516 $3.34 $23,856

1410 1.9 23 12 8,125 7,602 3,994 $4.43 $33,660

1431 1.7 29 22 9,479 9,375 5,626 $10.24 $95,960

1433 0.5 7 7 3,978 3,978 7,835 $3.04 $12,109

1440 1.5 18 15 15,155 14,588 9,657 $2.15 $31,314

800G 0.3 2 2 3,726 3,726 12,298 $3.28 $12,236

Dolly Varden 11.8 155 114 109,890 103,954 8,793 $11.87 $1,234,068

DVA 1.3 18 15 7,480 7,292 5,640 $15.49 $112,964

LC5000 2.3 26 21 23,659 23,089 10,176 $2.57 $59,360

N500A 0.2 3 3 1,697 1,697 7,318 $4.92 $8,348

Old Hwy 299 2.5 52 39 16,040 15,064 6,074 $15.52 $233,836

PR1106 0.6 5 5 10,417 10,417 17,639 $3.02 $31,477

R1000 2.1 21 13 8,914 8,775 4,164 $3.84 $33,653

R2100 0.2 2 2 1,557 1,557 7,402 $3.05 $4,746

R3351 0.1 1 1 750 750 6,544 $1.36 $1,017

R3800 0.9 11 10 9,796 9,774 11,364 $5.89 $57,576

R3810 0.1 2 1 5,000 3,500 43,126 $2.90 $10,165

RC-2 1.5 25 14 10,122 9,120 6,168 $14.77 $134,682

Table note: 

Costs above include only heavy equipment costs for site specific treatments and laborers for culvert installations. 

Costs do not include equipment mobilization, road opening, heavy equipment requirements for road drainage 

treatments, culvert materials costs, mulch and seeding costs, project layout, coordination, oversight, report 

preparation, or overhead.
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 27

The 1140, 1440, LC5000 and PR1106 roads have the highest treatment priority because each road 

appeared in the top 30 roads and in all three criteria. These roads have relatively high potential 

sediment yield, high yield per mile of road, and high treatment cost-effectiveness. The other roads 

listed in Table 16 ranked high in at least two of the three criteria. 

SUB-WATERSHEDS

This analysis establishes a treatment priority for individual sub-watersheds using database queries 

and data for sites assessed by PCFWWRA and RNSP, and not decommissioned. Sites assessed by 

others were omitted because we determined the volume estimates are inaccurate (Bundros and 

Short, 2009). The analysis presents basic information for each sub-watershed, and computes the 

total potential sediment yield per mile of road (yds3/mile) for each sub-watershed. The query 

evaluates sites with medium to high erosion potentials in sub-watersheds where at least 40 percent 

of the road miles had been evaluated. The results were sorted by the potential sediment yield per 

mile of road and assigned a priority ranging from very low to very high. The priority for each subwatershed was assigned by comparing its yield per mile to the highest yield per mile value of the 

sub-watersheds considered. The very low priority sub-watersheds would yield 0-20 percent of the 

yield per mile for the sub-watershed with the highest value, and the very high priority subwatershed would yield 80-100 percent of the highest yielding sub-watershed.

Table 17 shows the query results and establishes a treatment priority for each sub-watershed by 

the total potential sediment yield per mile of road. Potential sediment yield per mile ranged from 

about 52 yds3/mile in Six Rivers Creek to 5,745 yds3/mile of road in Lee Creek. Lee Creek was 

considered an outlier in this analysis because its yield was nearly twice the value of the next highest 

sub-watershed. Potential sediment yield averaged about 1,140 yds3/mile.

Also from the Table 17, Lacks Creek has the highest potential sediment yield, equal to about 

142,000 yds3. Lacks Creek is more than twice the size of the next largest sub-watershed, so the fact 

that it has the highest total potential yield is no surprise. Of the 42 sub-watersheds considered, 14

sub-watersheds can potentially yield more than 10,000 yds3 of sediment per square mile.
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 28

Table 17. Sub-watershed treatment priority based on potential sediment yield per mile of road.

Sub-Watershed Acres

Roads Potential Sediment Yield SubWatershed

Priority

Total

(mi)

Evaluated

(%)

Density

(mi/mi2

)

Total

(yds3)

Yield/mile2

(yds3/mi2)

Yield/Mile

(yds3/mi)

Lee 292 3.1 100% 6.7 17,546 38,493 5,745 Very High

Wiregrass 1,153 9.5 92% 5.3 34,515 19,152 3,635 Very High

Johnson Prairie 386 2.2 87% 3.6 7,338 12,179 3,371 Very High

Toss-Up 1,709 15.7 97% 5.9 43,662 16,355 2,778 High

Pilchuck 1,086 8.8 92% 5.2 24,398 14,381 2,773 High

Loin 601 5.0 81% 5.3 12,515 13,328 2,517 High

Timbo 229 3.8 94% 10.7 8,769 24,479 2,295 High

Headwaters_W 179 1.7 52% 6.0 3,740 13,360 2,235 High

Stover 544 4.8 56% 5.7 9,885 11,621 2,052 Medium

Garcia 905 10.1 90% 7.1 20,627 14,581 2,049 Medium

Powerline 408 4.3 94% 6.8 8,874 13,916 2,048 Medium

Dolly Varden 2,151 23.5 92% 7.0 44,327 13,191 1,883 Medium

Tom 259 2.2 93% 5.4 4,067 10,045 1,853 Medium

Coyote 5,043 16.5 57% 2.1 30,159 3,827 1,829 Medium

June 125 0.9 100% 4.8 1,694 8,701 1,804 Medium

Lacks 10,977 82.5 85% 4.8 142,333 8,298 1,724 Medium

Smokehouse 426 5.8 74% 8.7 9,210 13,850 1,594 Medium

Negro Joe 806 9.5 72% 7.6 12,380 9,830 1,301 Low

George 699 6.4 100% 5.8 8,145 7,461 1,282 Low

Twin Lakes 811 9.8 90% 7.8 11,875 9,369 1,206 Low

Fern Prairie 509 6.5 73% 8.2 7,310 9,194 1,124 Low

Garrett 2,643 21.1 62% 5.1 18,688 4,525 886 Low

Minor 8,248 84.6 87% 6.6 73,535 5,706 869 Low

Burley 255 3.0 91% 7.4 2,564 6,444 866 Low

Lupton 3,329 41.1 62% 7.9 35,637 6,852 866 Low

Headwaters_M 1,688 15.4 72% 5.8 12,352 4,684 802 Low

Snow Camp 773 8.2 66% 6.8 6,262 5,182 767 Low

Lake Prairie 2,144 18.8 82% 5.6 14,035 4,190 746 Low

Panther 3,800 30.7 95% 5.2 21,767 3,666 708 Very Low

Jena 246 4.1 47% 10.7 2,715 7,061 660 Very Low

Cashmere 861 9.3 80% 6.9 5,554 4,130 595 Very Low

Pardee 1,985 23.6 68% 7.6 11,280 3,638 478 Very Low

Christmas Prairie 455 6.9 73% 9.8 3,033 4,267 437 Very Low

Noisy 4,030 46.8 73% 7.4 19,326 3,069 413 Very Low

Marquette 492 6.7 91% 8.7 2,747 3,572 410 Very Low

Cool Springs 737 9.5 45% 8.3 3,592 3,118 377 Very Low

Santa Fe 530 8.7 65% 10.5 3,003 3,625 344 Very Low

Debris Torrent 129 2.0 91% 9.8 559 2,770 283 Very Low

High Prairie 3,476 40.1 50% 7.4 8,011 1,475 200 Very Low

Joplin 441 3.7 90% 5.4 657 954 176 Very Low

Ayers 242 3.6 97% 9.5 511 1,350 143 Very Low

Six Rivers 741 9.2 57% 8.0 479 414 52 Very Low
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 29

PRIORITIZING AREAS WITHIN THE WATERSHED USING A GIS SPATIAL ANALYSIS

This analysis establishes a treatment priority for areas in the upper watershed using a GIS spatial 

analysis and data from sites assessed by PCFWWRA and RNSP, and not decommissioned. Data from 

sites assessed by others were not used. Rather than focusing on a specific road or sub-watershed, 

this method analyzes potential sediment yield throughout the upper watershed and highlights 

discrete areas by the concentration or density of potential sediment yield. The spatial analysis 

ignores sub-watershed boundaries.

The analysis uses both numeric and spatial data. Numeric data are the potential sediment yield 

values for sites as estimated by the field crews, and the spatial data comes from GIS point coverage 

for each site evaluated during the assessment. Because each point represents the location of a site, 

the analysis can evaluate the potential sediment yield of one site in relation to the potential 

sediment yield of sites that surround it. 

Using GIS and the data sources described above, the density or “hot spots” (potential sediment yield 

per square mile) throughout the upper Redwood Creek watershed was computed. Simply stated, an 

analysis tool found in GIS software can scan and analyze a contiguous area using a moving one 

square mile circular “window.” As the window sweeps across the landscape, it notes the potential 

sediment yield at each site location and adds to it the yield associated to neighboring sites if they 

are within one square mile of the site being evaluated. The results of this analysis are shown in 

Figure 8. The darkest colors represent the areas that contain the highest density of potential 

sediment yield, suggesting another possible treatment priority.

PRIORITIZING SUB-WATERSHEDS USING RISK ANALYSES

This analysis establishes treatment priorities using a numeric risk analysis and data from sites

assessed by PCFWWRA and RNSP, and not decommissioned. Rather than analyzing a specific road 

or broad contiguous area, this method prioritizes each sub-watershed based on specific criteria. 

Similar to other analyses, at least 40 percent of the road length in each sub-watershed must have 

been assessed to be considered, and only sites with medium or higher erosion potential are 

included in the analysis. The analysis is performed twice. First, evaluates sub-watersheds based on 

the likelihood for and magnitude of potential erosion which we call resource threat. Then,

anadromous salmonids are added to the analysis that considers salmonids as the resource at risk.

RESOURCE THREAT

This risk analysis establishes a sub-watershed treatment priority based on resource threat, or the 

likelihood for and magnitude of erosion in each sub-watershed. The resource threat for each subwatershed considers three criteria: 1) potential sediment yield; 2) critical crossings, and; 3) 

Shalstab. Resource threat was computed as follows: 

Resource Threat = Yield + CXing + Shalstab

where, for each sub-watershed:

Yield is the total potential sediment yield for the sub-watershed,

CXing is the number of critical crossings in the sub-watershed, and
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 30

Shalstab is the number of Shalstab sites in the sub-watershed.

Weighted values were assigned to each criterion (Appendix G) based on the actual range of values 

for each criterion. The weighted values were then summed to create a final score for each subwatershed. The final scores were sorted from high to low values and a sub-watershed treatment 

priority assigned based on 20% breaks in cumulative total scores. The results are shown in Figure 

9 and Table 18 and suggest that Lacks, Minor and Dolly Varden creeks have the highest treatment

priority based on potential resource threat, followed by Toss-Up, Lupton and Wiregrass creeks. 

The results are in general agreement with the spatial analysis for potential sediment yield density 

(Figure 8).
Lacks

Minor

Garrett

Stover

Bradford

Coyote

Johnson Prairie

Molasses

Devils

Panther

George

Dolly Varden

Lee

Garcia

Cashmere

Pilchuck

Toss-Up

Sweathouse

Captain

Negro Joe

Windy

Squirrel Tail

Emmy Lou

Cut-Off Meander

Gunrack

Simon

Minon

June

Wiregrass

Loin

Santa Fe

Greenpoint

Lupton

Fern Prairie

Christmas Prairie

Jena

Noisy

Cool Springs

Six Rivers

Upper Panther

Last Gap

Lineament

Headwaters_E

Headwaters_M

High Prairie

Lake Prairie

Pardee

Marquette

Timbo

Powerline

Snow Camp

Smokehouse

Twin Lakes

Burley

Tom

Headwaters_W

Debris Torrent

Ayers

Beaver

0 1 2 4 6 8

Miles

Source: RNSP GIS - N:\GIS_Maps\user_maps\60_UBErosionPreventionRanking\2010Update

Compiled: January 2011

*The road assessment data collected between 1996 and 2004

within the upper Redwood Creek watershed includes a volume

estimate of potential sediment yield to streams at each site

evaluated. For each site, the erosion potential (likelihood of

failure) was estimated as either low, medium or high.

This map shows the density of potential sediment yield for those

sites rated to have medium to high erosion potential. It was

produced using a GIS analysis that calculates density using

a moving one square mile circular window.

Upper Redwood Creek Watershed

Potential Sediment

Yield Density

Status of Inventory Data

Limited Data

Unsurveyed

Parklands

Watershed divides

Streams (1:24k)

Potential Sediment

Yield Density*

(cubic yards/square mile)

0 - 5,000

5,000 - 15,000

15,000 - 30,000

30,000 - 45,000

45,000 - 70,000

70,000 - 100,000
Lacks

Minor

Garrett

Stover

Bradford

Coyote

Johnson Prairie

Molasses

Devils

Panther

George

Dolly Varden

Lee

Garcia

Cashmere

Pilchuck

Toss-Up

Sweathouse

Captain

Negro Joe

Windy

Squirrel Tail

Emmy Lou

Cut-Off Meander

Gunrack

Simon

Minon

June

Wiregrass

Loin

Santa Fe

Greenpoint

Lupton

Fern Prairie

Christmas Prairie

Jena

Noisy

Cool Springs

Six Rivers

Upper Panther

Last Gap

Lineament

Headwaters_E

Headwaters_M

High Prairie

Lake Prairie

Pardee

Marquette

Timbo

Powerline

Snow Camp

Smokehouse

Twin Lakes

Burley

Tom

Headwaters_W

Debris Torrent

Ayers

Beaver

Source: RNSP GIS - N:\GIS_Maps\user_maps\60_UBErosionPreventionRanking\2010Updates

Compiled: February, 2011

0 1 2 4 6 8

Miles

Sub-watershed Treatment Priority

Based on Resource Threat

Upper Redwood Creek Watershed

*This map shows the result of a numerical risk analysis that is

based on resource threat (potential sediment yield + critical

crossings + Shalstab). Sub-watersheds are ranked only

if at least 40% of the roads in the sub-watershed were assessed.

Sub-Watershed Priority*

Very High

High

Medium

Low

Very Low

Not Ranked

Status of Inventory Data

Limited Data

Currently Unsurveyed

Park lands

Streams (1:24k)

Watershed divides
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 33

Table 18. Sub-watershed treatment priority based on resource threat. 

Sub-Watershed Area 

(ac)

Weighting Values for:

Total

Score Potential Sub-Watershed Priority

Sediment

Yield

Critical

Crossings Shalstab

Lacks 10,977 9 9 9 27 Very High

Minor 8,248 9 9 9 27 Very High

Dolly Varden 2,151 9 7 3 19 Very High

Toss-Up 1,709 7 3 7 17 High

Lupton 3,329 7 3 5 15 High

Wiregrass 1,153 7 3 5 15 High

Coyote 5,043 5 5 3 13 Medium

Negro Joe 806 3 7 3 13 Medium

Garcia 905 5 3 3 11 Medium

Noisy 4,030 5 5 1 11 Medium

Panther 3,800 5 3 3 11 Medium

Pilchuck 1,086 5 1 5 11 Medium

Garrett 2,643 3 5 1 9 Low

Pardee 1,985 3 3 3 9 Low

Lake Prairie 2,144 3 1 3 7 Low

Johnson Prairie 386 1 5 0 6 Low

George 699 1 3 1 5 Low

Headwaters_M 1,688 3 1 1 5 Low

Lee 292 3 1 1 5 Low

Loin 601 3 1 1 5 Low

Powerline 408 1 3 1 5 Low

Twin Lakes 811 3 1 1 5 Low

Snow Camp 773 1 3 0 4 Very Low

Christmas Prairie 455 1 1 1 3 Very Low

Debris Torrent 129 1 1 1 3 Very Low

High Prairie 3,476 1 1 1 3 Very Low

Joplin 441 1 1 1 3 Very Low

June 125 1 1 1 3 Very Low

Marquette 492 1 1 1 3 Very Low

Six Rivers 741 1 1 1 3 Very Low

Stover 544 1 1 1 3 Very Low

Timbo 229 1 1 1 3 Very Low

Burley 255 1 1 0 2 Very Low

Cashmere 861 1 0 1 2 Very Low

Cool Springs 737 1 1 0 2 Very Low

Fern Prairie 509 1 1 0 2 Very Low

Headwaters_W 179 1 1 0 2 Very Low

Jena 246 1 1 0 2 Very Low

Santa Fe 530 1 1 0 2 Very Low

Smokehouse 426 1 1 0 2 Very Low

Tom 259 1 1 0 2 Very Low

Ayers 242 1 0 0 1 Very Low
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 34

RESOURCE THREAT AND RESOURCE AT RISK

This risk analysis uses the same methods used to describe resource threat, but now integrates 

anadromous salmonids in each sub-watershed as the resource at risk. Doing so adds a biological 

element to the previous analysis that prioritized sub-watershed treatment only in terms of the 

likelihood for and magnitude of potential erosion, or resource threat. In this analysis risk is defined 

as follows:

Risk = Resource Threat + Resource at Risk

Resource Threat was defined in the previous analysis. Resource at Risk considers the number of 

anadromous salmonid species observed in each sub-watershed. Salmonid distribution information 

for the Redwood Creek watershed is from documented stream surveys performed since 1965 and is 

shown in Figure H-1 (Appendix H). 

The results from this analysis are shown in Figure 10 and Table 19. Lacks and Minor creeks are the 

highest priority for treatment because both have high sediment threats and support at least three

salmonid species. The treatment priority for sub-watersheds such as Coyote, Panther and Pilchuck 

creeks moved from medium in the previous analysis to high, because they have moderately high 

sediment threats and support populations of at least two salmonid species. Other subwatersheds,

such as Toss-up, Lupton and Wiregrass fell in treatment priority even though each supports one 

salmonid species. While High Prairie Creek supports two salmonid species, its treatment priority is

relatively low because of its low sediment threat. 

CRITICAL CROSSINGS

Stream crossings are a significant sediment threat to aquatic and riparian habitats and water 

quality because there are so many crossings built throughout north coast watersheds. Crossings 

that can divert a stream from its natural watercourse are especially problematice, because of the 

magnitude of erosion that can occur if the stream diverts (see Watershed Improvement Plan). 

Stream crossings that are especially prone to diversion are those we refer to as ‘critical’ crossings. 

Critical crossings are those most likely to divert during a large storm because they have a diversion 

potential, undersized culvert and at least medium plug potential.

Considerable progress has been made in reducing the number of critical crossings in the upper 

watershed, but more work needs to be done. To identify areas where the concentration of critical 

crossings remains high, we performed a GIS spatial analysis that computed the density of critical 

crossings per square mile across all of the assessment areas. The results of this analysis are shown 

in Figure 11. The darkest colors represent ‘hot spots’, or the highest concentrations of critical 

crossings and areas of the highest risk.
Lacks

Minor

Garrett

Stover

Bradford

Coyote

Johnson Prairie

Molasses

Devils

Panther

George

Dolly Varden

Lee

Garcia

Cashmere

Pilchuck

Toss-Up

Sweathouse

Captain

Negro Joe

Windy

Squirrel Tail

Emmy Lou

Cut-Off Meander

Gunrack

Simon

Minon

June

Wiregrass

Loin

Santa Fe

Greenpoint

Lupton

Fern Prairie

Christmas Prairie

Jena

Noisy

Cool Springs

Six Rivers

Upper Panther

Last Gap

Lineament

Headwaters_E

Headwaters_M

High Prairie

Lake Prairie

Pardee

Marquette

Timbo

Powerline

Snow Camp

Smokehouse

Twin Lakes

Burley

Tom

Headwaters_W

Debris Torrent

Ayers

Beaver

Source: RNSP GIS - N:\GIS_Maps\user_maps\60_UBErosionPreventionRanking\2010Updates

Compiled: February, 2011

0 1 2 4 6 8

Miles

Sub-watershed Treatment Priority

Based on Resource Threat and

Resource at Risk

Upper Redwood Creek Watershed

*This map shows the result of a numerical risk analysis that is

based on resource threat (potential sediment yield + critical

crossings + Shalstab) and resource at risk (anadromous salmonids)

Sub-watersheds are ranked only if at least 40% of the roads in

the sub-watershed were assessed.

Sub-Watershed Priority*

Very High

High

Medium

Low

Very Low

Not Ranked

Status of Inventory Data

Limited Data

Currently Unsurveyed

Park lands

Streams (1:24k)

Watershed divides
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 36

Table 19. Sub-watershed treatment priority based on resource threat and resource at risk. 

Sub-Watershed Area

(ac)

Fish (Resource at 

Risk) Scores

Total

Score

SubWatershed

# of Priority SpeciesWeighting 

Value

Resource 

Threat

Resource 

at Risk

(3x 

weight)

Lacks 10,977 4 9.00 27 27 54 Very High

Minor 8,248 3 6.75 27 20 47 Very High

Coyote 5,043 3 6.75 13 20 33 High

Dolly Varden 2,151 2 4.50 19 14 33 High

Panther 3,800 2 4.50 11 14 25 High

Pilchuck 1,086 2 4.50 11 14 25 High

Toss-Up 1,709 1 2.25 17 7 24 Medium

Lupton 3,329 1 2.25 15 7 22 Medium

Wiregrass 1,153 1 2.25 15 7 22 Medium

Garcia 905 1 2.25 11 7 18 Medium

Noisy 4,030 1 2.25 11 7 18 Medium

High Prairie 3,476 2 4.50 3 14 17 Low

Garrett 2,643 1 2.25 9 7 16 Low

Pardee 1,985 1 2.25 9 7 16 Low

Lake Prairie 2,144 1 2.25 7 7 14 Low

Negro Joe 806 0 0.00 13 0 13 Low

Twin Lakes 811 1 2.25 5 7 12 Low

Loin 601 1 2.25 5 7 12 Low

Snow Camp 773 1 2.25 4 7 11 Low

Six Rivers 741 1 2.25 3 7 10 Very Low

Smokehouse 426 1 2.25 2 7 9 Very Low

Cashmere 861 1 2.25 2 7 9 Very Low

Santa Fe 530 1 2.25 2 7 9 Very Low

Jena 246 1 2.25 2 7 9 Very Low

Johnson Prairie 386 0 0.00 6 0 6 Very Low

Lee 292 0 0.00 5 0 5 Very Low

Headwaters_M 1,688 0 0.00 5 0 5 Very Low

George 699 0 0.00 5 0 5 Very Low

Powerline 408 0 0.00 5 0 5 Very Low

Joplin 441 0 0.00 3 0 3 Very Low

Christmas Prairie 455 0 0.00 3 0 3 Very Low

Debris Torrent 129 0 0.00 3 0 3 Very Low

Timbo 229 0 0.00 3 0 3 Very Low

June 125 0 0.00 3 0 3 Very Low

Marquette 492 0 0.00 3 0 3 Very Low

Stover 544 0 0.00 3 0 3 Very Low

Fern Prairie 509 0 0.00 2 0 2 Very Low

Headwaters_W 179 0 0.00 2 0 2 Very Low

Cool Springs 737 0 0.00 2 0 2 Very Low

Burley 255 0 0.00 2 0 2 Very Low

Tom 259 0 0.00 2 0 2 Very Low

Ayers 242 0 0.00 1 0 1 Very Low
Lacks

Minor

Garrett

Stover

Bradford

Coyote

Johnson Prairie

Molasses

Devils

Panther

George

Dolly Varden

Lee

Garcia

Cashmere

Pilchuck

Toss-Up

Sweathouse

Captain

Negro Joe

Windy

Squirrel Tail

Emmy Lou

Cut-Off Meander

Gunrack

Simon

Minon

June

Wiregrass

Loin

Santa Fe

Greenpoint

Lupton

Fern Prairie

Christmas Prairie

Jena

Noisy

Cool Springs

Six Rivers

Upper Panther

Last Gap

Lineament

Headwaters_E

Headwaters_M

High Prairie

Lake Prairie

Pardee

Marquette

Timbo

Powerline

Snow Camp

Smokehouse

Twin Lakes

Burley

Tom

Headwaters_W

Debris Torrent

Ayers

Beaver

Source: RNSP GIS - N:\GIS_Maps\user_maps\60_UBErosionPreventionRanking\2010Update

Compiled: January 2011

*The road assessment performed between 1996 and

2004 within the upper Redwood Creek watershed

evaluated road-stream crossings and their drainage

structures. Drainage structures were evaluated for

their capacity as well as their diversion and plug

potential. Crossings having a diversion potential, a

medium to high plug potential, and an undersized

culvert are referred to as “Critical Crossings” and should be

treated as soon as possible.

This map shows the density of Critical Crossings for the area

surveyed. It was produced by a GIS analysis that calculated

density using a moving one square mile circular window.

Status of Inventory Data

Limited Data

Unsurveyed

Parklands

Watershed divides

Streams (1:24k)

Number of Critical

Crossings/square mile*

<1

1 - 10

10 - 20

20 - 40

40 - 60

0 1 2 4 6 8

Miles

Critical Crossing Density

Upper Redwood Creek Watershed
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 38

Discussion

Several different analyses have been presented that prioritize erosion control and prevention 

treatments in the upper Redwood Creek watershed. Each analysis works at a different scale, and 

has its strengths and weaknesses.

The first analysis established a treatment priority for individual roads and sub-watersheds using 

database queries. Roads were prioritized based on: 1) total potential sediment yield for the 

untreated road reach; 2) total potential sediment yield per mile of road, and; 3) treatment costeffectiveness. Sub-watersheds were prioritized by total potential sediment yield per mile of road. 

These simple analyses characterize each road and sub-watershed by potential sediment yield and 

cost-effectiveness, and are based on simple databases queries. Analysis results are most useful 

when all roads are controlled by a single landowner. Its utility diminishes when roads cross 

multiple ownership or sub-watershed boundaries, because the analysis lacks a spatial reference.

The second analysis established a treatment priority for areas of high potential sediment yield 

density or “hot spots” using a GIS spatial analysis. The analysis is blind to sub-watershed 

boundaries. Its ability to highlight discrete areas containing a potentially high cumulative potential 

sediment yield is its greatest strength. The spatial reference provided in this analysis is well suited 

to establishing treatment priorities at all planning scales. A disadvantage to this method is that it 

does not consider what percentage of an area has been evaluated. Thus, the analysis can miss areas 

of high potential sediment yield density if adjacent areas have not been fully evaluated and included 

in the analysis.

The third analysis established a treatment priority for sub-watersheds by performing two separate 

risk analyses. The first analysis was based only on resource threat (the likelihood for and the 

magnitude of potential erosion), and the second integrated the resource at risk (anadromous 

salmonids) into the analysis. Depicting the risk to salmonid populations at a watershed scale is 

perhaps the greatest strength of this analysis that integrates specific site information such as 

potential sediment yield and critical crossings, with watershed attributes such as hillslope stability 

(Shalstab) and salmonids. A disadvantage to this method is that it is based on sub-watershed 

boundaries and, therefore, does not evaluate interfluves between sub-watersheds. Interfluves tend 

to have the highest road densities (Table A-1) and they deliver sediment directly to Redwood Creek. 

We also believe DEMs used to run the Shalstab model tend to underestimate steepness, especially 

in the confined streamside areas. Underestimating steepness in these areas could reduce the 

predicted resource threat at individual sites and the sub-watershed ranking.

The risk analysis is also sensitive to how much of a sub-watershed has been assessed. A subwatershed is considered in the analysis only if at least 40 percent of the road length in the subwatershed had been evaluated. Therefore, the percentage of roads and/or the number of sites 

evaluated in each sub-watershed must be considered when reviewing the analysis results. 

The final analysis identified areas that contain high concentrations of critical crossings. The 

analysis is blind to ownership and sub-watershed boundaries, and is well suited to planning efforts 
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 39

at all landscape scales. However, the completeness of road assessments in neighboring areas must 

be considered when reviewing results.

The ‘best’ prioritization method would probably use a combination of the analyses presented in this 

report, and would depend on the scale and objectives of the planning effort. For example, a smaller 

landowner willing to implement an erosion control project might use database queries in 

combination with the spatial analysis to prioritize work on their land. If the protection of subwatersheds that supports the greatest number of salmonid species is the objective, then the 

numeric risk analysis that integrates salmonid information would be appropriate in combination 

with the database query that considers treatment cost-effectiveness. The spatial analysis could also 

help pinpoint priority areas within the sub-watershed. 

Our preference for prioritizing areas for treatment would consider the importance of limiting 

sedimentation in the main channel of Redwood Creek, because of its importance to fisheries and the 

threat sediment poses to the downstream park resources. Outside of the Prairie Creek subwatershed, the main channel of Redwood Creek represents about 70 percent of all accessible 

anadromous salmonid habitat in the Redwood Creek watershed (California Resources Agency, 

2002), and severe aggradation of the main channel, as experienced during past large storms, would 

threaten the riparian areas in the park, including the alluvial old-growth groves. Thus, a 

watershed-wide planning effort that sets sediment reduction to the main channel of Redwood 

Creek as its primary objective could use the numeric risk analysis based on resource threat in 

combination with the analysis that identifies the “hot spots” throughout the entire watershed.

WATERSHED IMPROVEMENT PLAN

We offer the following suggestions for land management practices that can protect aquatic and 

riparian habitats and move the watershed closer to recovery and meeting the objectives of the 

Redwood Creek TMDL. 

1. Continue Erosion Control and Prevention Efforts in the Upper Watershed

Significant progress has been made in treating potential erosion sites and meeting identified 

hillslope targets in the TMDL. However, it’s imperative this work continues in the upper watershed, 

where only 19 percent of the estimated controllable sediment load has been treated. Sediment load 

reduction should occur throughout the watershed, especially in areas identified as high priority for 

treatment in this report. Medium to high urgency sites identified in the road assessments should be 

treated at the earliest possible date. Redwood National and State Parks is willing to help develop 

projects and facilitate project implementation. The park looks forward to working with private 

landowners, non-profit organizations and other government agencies to seek funds and help 

implement erosion-control and prevention work.
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 40

2. Treat Stream Crossings that have Diversion Potential

Erosion caused by stream diversions during large storms can be significant and is preventable, and 

the prevention of diversions is perhaps the most cost-effective erosion control treatment. 

Diversion potentials at stream crossings should be treated, independent of other established 

treatment priorities. 

Based on our observations in the Redwood Creek watershed, stream diversions can cause severe 

gully erosion that often leads to significant landslide erosion. Studies performed in the Redwood 

Creek watershed have shown that: 1) stream diversions can account for a significant portion of a 

sediment budget during large storms; 2) the erosion volume from diversions can far exceed the 

volume contained in the crossings from which the streams diverted, and; 3) stream diversions are 

preventable (Weaver and Hagans, 1987; Best and others, 1995).

Of the approximately 2,540 stream crossings originally evaluated by PCFWWRA and RNSP, nearly 

1,590 crossings (63%) had a diversion potential and 464 crossings (18% of all crossings) were 

critical crossings. Upgrade and decommission projects have treated 336 (21%) of the assessed 

potential diversion crossings, and 110 (24%) of the assessed critical crossings. Crossings with 

diversion potential (especially critical crossings) in the upper watershed should receive the highest

treatment priority.

Diversion prevention efforts should rely on permanently installed critical dips as defined by

Weaver and Hagans (1994). Waterbars are insufficient and are not a substitute for permanent, 

well-constructed critical dips. If the crossing is the low point of the road and acts as a critical dip, 

the surface of the road should be insloped towards the culvert inlet to prevent surface runoff from 

reaching the downstream fillslope that would erode. The outflows of critical dips should be rock 

armored, especially if the critical dip is centered over the crossing and it drains to the downstream 

side of the crossing fill.

3. Decrease Road Density

The road density in the upper watershed is too high and should be reduced. The average road 

density for the entire watershed is about 4.8 miles per square mile. However, roads are not 

distributed evenly throughout the watershed. In the lower watershed, mostly park lands, road 

density is about 2.4 miles/square mile while in the upper watershed, mostly private lands, road

density is about 6.4 miles/square mile. Road density has been reduced in the upper watershed 

since cooperative projects have decommissioned roads, but the fact that road density approximates 

the density of all streams (7.5 miles/square mile) in the watershed suggests it is still too high. New 

roads needed for timber harvest should be built as temporary roads. Roads not needed for a 

decade or more should be either permanently or temporarily decommissioned. A road density of 

about 5.0 miles per square mile in any sub-watershed would be a reasonable initial goal. With 

fewer roads, long-term sediment delivery to Redwood Creek and its tributaries, and maintenance 

needs and costs would be reduced. 

4. Provide Long-Term Road Maintenance

Based upon road assessments and completed work, about 55 percent of the assessed roads in 

Redwood Creek are being maintained (or are maintenance-free because they have been 
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 41

decommissioned). In 2004, we reported that about 32 percent of all roads assessed were being 

maintained (Bundros et al., 2004), so this is a significant improvement. Road inspection and 

maintenance will be critical for watershed recovery because the potential sediment impacts 

associated with roads will exist as long as roads remain on the landscape. We encourage 

landowners to voluntarily adopt measures similar to those found in Green Diamond Resource 

Company’s Aquatic Habitat Conservation Plan (GDRCo, 2006) that contains explicit standards for 

road inspections and maintenance. Roads should be maintained into perpetuity or they should be 

permanently or temporarily decommissioned.

5. Improve Stream Crossing Construction Standards

Based on original assessment data, we estimated there were about 5,000 stream crossings in the 

entire upper Redwood Creek watershed prior to treatments (Bundros et al., 2004). While about 

540 crossings have either been subsequently upgraded or decommissioned, there are still a 

significant number of stream crossings in the upper watershed. Stream crossing design and 

construction standards should reflect this threat to salmonids and water quality and follow 

guidelines described by Cafferata and others (2004). 

When crossings are reconstructed, sediment accumulated upstream of the crossing should be 

excavated from the channel before a new culvert is installed. This allows a culvert to be installed 

deeper and the crossing to be built with a minimum amount of fill. Placing the culvert deeper in the 

fill will ensure it more closely conforms with the original stream channel grade, which will allow 

sediment and debris to be transported through the culvert instead of being deposited at the culvert 

inlet which can plug the culvert and cause failure.

Whether new or reconstructed, crossing fill should be thoroughly compacted by appropriate 

equipment (not crawler tractors), especially along the outer edge of the fill prism and around the 

newly placed culvert. Rock armor on the downstream fillslope of the crossing is not a substitute for 

proper compaction, but it is recommended to more fully protect the crossing if the culvert were to 

plug or otherwise fail.

6. Avoid Throughcut Road Construction

Throughcut road construction should be avoided because such roads are impossible to drain 

properly. This is especially important for roads that lead to landings where concentrated surface 

runoff can saturate the outer landing edge and cause landing failure, or to stream crossings where 

throughcut road construction would make it difficult to hydrologically disconnect road runoff from 

the crossing.

7. Drainage, Drainage, Drainage

Road surface drainage is an integral part of all road systems. When properly configured by ditch 

relief culverts, outsloped road surfaces and/or rolling dips, road surface drainage distributes

surface runoff evenly along a road, and prevents concentrated runoff that leads to sheet, rill and 

gully erosion. Reducing the amount of road and inboard ditch that drains directly into streams 

reduces sediment delivery to streams. Where inboard ditches are needed and must be improved 

along existing roads, the ditches can be excavated into the inside edge of the road so that cutbanks 

are not disturbed. Many roads are wider than needed. By excavating ditch lines into the road as 
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 42

opposed to the cutbank, cutbank failures can be prevented, and road widths and maintenance costs

can be reduced.

8. Account for Highway 299 When Installing Culverts Downslope of the Highway

When sizing culverts it is important to consider the effects state Highway 299 has on the routing of 

surface water. Standard culvert sizing methods that ignore the effects of the highway will either 

overestimate or underestimate the drainage area, storm discharge and culvert diameter needed at 

crossings located below the highway. There are about 11 miles of state Highway 299 in the 

Redwood Creek watershed. 

Hydrologic effects from state Highway 299 are likely to be more pronounced when it crosses 

middle hillslope positions, where drainage density tends to be high and stream channels are not 

fully formed. Highway culverts are not always installed for the smallest streams, so streamflow can 

be diverted by inboard ditches and storm drains to a neighboring drainage. The highway surface 

also can collect a vast amount of surface runoff that can be discharged onto previously unchanneled 

hillslope areas. These effects could result in increased channel erosion, because of the flashiness 

and quantity of runoff, especially when rapid snow melt occurs. Therefore, the surface drainage 

patterns and the placement of drainage structures along state Highway 299 should be considered 

when sizing culverts in areas downslope of the highway. Table 20 shows how the length of state 

Highway 299 is distributed through different sub-watersheds and interfluves. 

Table 20. Sub-watersheds and interfluves affected by state Highway 299.

(listings are in an easterly direction along the highway route.)

Watershed/Interfluve

State Highway 299

Miles in Watershed 

(mi)

Density in Watershed 

(mi/mi2

)

Santa Fe Creek 0.7 0.9

Greenpoint Creek 0.7 1.4

Greenpoint-Lupton 1.5 1.2

Lupton Creek 1.0 0.2

Lupton-Fern Prairie 0.5 1.3

Negro Joe-Windy 0.1 0.2

Negro Joe Creek 1.2 0.9

Captain Creek 3.8 1.8

Sweathouse-Captain 0.2 0.4

Sweathouse Creek 0.2 0.1

Windy Creek 0.6 0.4

9. Restore Riparian Function along Redwood Creek

Riparian conditions along Redwood Creek must improve before large woody debris can once again 

occupy the main channel of Redwood Creek in sufficient quantities needed for nutrient cycling, 

channel complexity, pool forming elements, shelter, and over-winter habitat for anadromous 

salmonids. Once dominated by coniferous forests that provided shade and a source of large woody 
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 43

debris, today an estimated 60 percent of the riparian corridor along Redwood Creek is dominated 

mostly by hardwood forests. Outside of the Prairie Creek sub-watershed, the main channel of 

Redwood Creek represents about 70 percent of all accessible anadromous salmonid habitat in the 

Redwood Creek watershed (California Resources Agency, 2002).

Riparian restoration opportunities exist through conifer planting and/or release, especially where 

conifers are already established below hardwood canopies. The greatest restoration opportunities 

likely exist in the reaches upstream of Highway 299 where the active channel is commonly less than 

100 feet wide, well within the growth potential of Douglas-fir that could provide channel spanning 

structure. Douglas-fir, and in some cases Redwood, are growing below a hardwood canopy along an 

estimated 12 river miles (20 percent) of the riparian corridor (Bundros et al., 2003). 

Conservation easements along the riparian corridor that include steep streamside slopes should 

also be considered, especially in the inner gorge areas upstream of state Highway 299. Obtained 

from willing landowners, riparian and inner gorge areas placed into conservation easements would 

ensure the long-term recruitment of large conifers to the main channel of Redwood Creek. Finally, 

we are encouraged by improved forest practices that are retaining greater numbers of conifers 

along streams for large woody debris recruitment and stream water temperature control, and on 

steep streamside areas where streamside landslides are an important recruitment mechanism for 

large woody debris. 

CONCLUSIONS

Partnerships have formed around the common objective of improving watershed conditions in 

Redwood Creek. This includes the formation of the Redwood Creek Watershed Group whose 

members represent about 90 percent of the ownership and/or management of land in the 

watershed (RCWG, 2006). These partnerships have spawned collaborative efforts that will 

ultimately improve and maintain salmonid habitat and water quality in Redwood Creek, and 

protect the downstream public trust resources in Redwood National and State Parks.

There are about 1,040 miles of road in the upper Redwood Creek watershed. Of those, about 910 

miles (87 percent) are on private lands and used for forest and ranch management. Road

assessments that have identified treatments and estimated costs have been completed on 463 miles 

roads. The estimated cost to treat these roads was reported by Bundros and Short (2009) and

averaged about $64,600 per mile. Extending unit costs to all roads (not state or county owned), the 

estimated total cost to treat all remaining logging and ranch roads in the upper watershed is about 

$44 million.

In the upper watershed, erosion control and prevention work has been performed through

cooperative efforts, individual landowner projects and through road work associated with timber 

harvest plans. Since efforts to prevent erosion from logging roads started in the mid-1990s, 61
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 44

miles of roads have been decommissioned and 120 miles of roads have been upgraded. About 294

stream crossings were upgraded with new and properly sized culverts or bridges, nearly 300

stream crossings were decommissioned, and 275 potentially unstable road reaches and/or landings 

were treated. The total sediment savings from this work was 531,000 yds3 or about 30 percent of 

the total potential sediment yield from assessed roads in the upper watershed. About $880,000 has 

been spent on completing road assessments and about $5.8 million on project implementation. 

Based on the average potential sediment yield of 2,600 yds3/mile of road on remaining assessed 

roads we estimate that about 2,340,000 yds3 of potential sediment yield associated with logging 

and ranch roads remains in the upper watershed. It represents about seven times the long-term 

annual sediment load of Redwood Creek. Of this total, about 60 percent is associated with fluvial 

sites such as stream crossings, and about 40 percent is associated with unstable road reaches and 

landings. 

We believe the values for total potential sediment yield are conservative and represent a minimum 

value. Extreme erosion potential is difficult to estimate, and we know that road assessments do not 

capture the full risk of stream diversions, landslides or debris torrents originating at roads. Also, 

we have observed offsite landsliding along confined stream channels caused by the rapid filling of 

landslide deposits. Potential sediment yield associated with such events is not included in yield 

estimates when sites are evaluated because doing so would be highly speculative.

The values for total potential sediment yield and sediment saved through erosion control and 

prevention efforts also do not include estimates for the amount of erosion that occurs from a road’s 

surface or inboard ditch. We know erosion from these surfaces occurs, but the rate of erosion is 

variable, influenced by such things as road design, the underlying materials of the road, whether or 

not the road is watered during use, the amount of use, etc. Thus, we chose to ignore volume 

estimates for surface erosion because of the uncertainties.

The erosion control and prevention work completed in the lower and upper watersheds has made 

significant progress toward meeting the goals of the Redwood Creek TMDL. Completed work has 

reduced potential sediment loading by about 36 percent of the TMDL’s required 60 percent load 

reduction. However, 71 percent of the total reduction occurred in the lower watershed, on park 

lands, compared to a 29 percent reduction in the upper watershed. While both represent 

significant reductions, more work is needed in the upper watershed to more fully distribute load 

reduction throughout the watershed. Moreover, seven percent of the load reduction in the upper 

watershed resulted from upgrading roads. Upgraded roads are not maintenance-free, so they must 

be maintained over the long-term to fully realize the benefits from the investments that reduced the 

potential for future road failures.

The trend of the 10-year rolling average annual sediment load for Redwood Creek has been 

encouraging. During periods of low to moderate flows, the 10-year rolling average fell below the 

1,900 tons/square miles/year TMDL target two times and it currently remains below the target. 

This trend clearly shows the target is attainable, but whether or not it can be sustained over the 

long-term is the question. The effects from the relatively moderate 1996 and 1997 storms are 

reminders that widespread erosion from roads will continue to occur during stressing events until 
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 45

the road network throughout the watershed is properly treated. Because of improved land 

management practices and watershed-wide efforts to prevent erosion, the watershed is recovering 

from the extreme erosional events in the 1960s and 1970s. However, the objective of the TMDL 

will not be met without additional work and a commitment to long-term road maintenance. More 

roads, especially in sensitive geomorphic settings, need to be decommissioned and others need to 

be upgraded and/or maintained for the 10-year rolling average annual sediment load to remain 

sustainably below the TMDL target through large storms.

Forest and ranch roads are a conundrum. They are needed for land management, but the high

density of roads constructed throughout the upper Redwood Creek watershed is a huge cumulative 

watershed impact that is largely ignored. While forest road construction standards have improved 

over the past years, there is still no mechanism for long-term road maintenance. Without a 

commitment to long-term road maintenance, we will always be addressing “legacy” effects from 

past forest rotations. We encourage landowners to voluntarily adopt measures similar to those 

found in Green Diamond Resource Company’s Aquatic Habitat Conservation Plan (GDRCo, 2006) 

that contains explicit standards for road inspections and maintenance. Roads should be maintained 

into perpetuity or they should be permanently or temporarily decommissioned.

Preventing erosion from logging roads, regardless of location, is important as all sediment is 

transported to the mainstem of Redwood Creek. Outside of the Prairie Creek tributary located in 

the lowermost portion of the watershed, the main channel of Redwood Creek represents about 70 

percent of all accessible anadromous salmonid habitat in the Redwood Creek watershed (California 

Resources Agency, 2002). The need to protect the main channel of Redwood Creek is further 

supported by the presence of the public trust resources found in Redwood National and State Parks, 

a UNESCO designated World Heritage Site located in the lower watershed. Erosion and 

sedimentation occurring upstream of the park can significantly impact the parks’ resources.

The different spatial and database analyses of road assessment data presented in this report 

consistently point to several sub-watersheds that should be considered high priority for treatment. 

Eastside tributaries include Coyote, Lacks and Minor creeks, and portions of Negro Joe Creek. 

Westside tributaries include Dolly Varden, Garcia, Lupton, Noisy, Panther, Pilchuck, Toss-Up and 

Wiregrass creeks, and the lower portions of Ayers, Cashmere, Marquette, Powerline and Timbo 

creeks. Based on the currently available road assessment data, the limited funds available for 

erosion control and prevention work would be best spent in these areas.

Regardless of how erosion control and prevention treatments are prioritized in the Redwood Creek 

watershed, it is important to remember that ground conditions change, some landowners are more 

able and willing to implement erosion control and prevention work than others, and logistics can 

complicate ‘priorities’. The most effective erosion control and prevention strategy for the Redwood 

Creek watershed should be flexible, and recognize the challenging nature of implementing projects 

across a large landscape with multiple owners. Erosion prevention efforts should also recognize 

the importance of the main channel of Redwood Creek to salmonids and the importance of 

protecting the public trust resources in the national park located at the downstream end of the 

watershed.
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 46

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Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 47

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Quality Attainment Strategy for Sediment. California North Coast Regional Water Quality 

Control Board.

California Regional Water Quality Control Board (RWQCB). 1998. Staff report for the proposed 

Redwood Creek Water Quality Attainment Strategy for sediment (total maximum daily 

loads and implementation plan). California Regional Water Quality Control Board, North 

Coast Region. 28 p.

California Regional Water Quality Control Board (RWQCB). 1998. Supplemental report for the 

proposed Redwood Creek Water Quality Attainment Strategy for sediment. California 

Regional Water Quality Control Board, North Coast Region. 74 p.

California Resources Agency. 2002. The North Coast Watershed Assessment Program Draft 

Redwood Creek Watershed Synthesis Report. February, 2002. California Resources Agency.

Cannata, S., R. Henly, J. Erler, J. Falls, D. McGuire and J. Sunahara. 2006. Redwood Creek watershed 

assessment report. Coastal Watershed Planning and Assessment Program and North Coast 

Watershed Assessment Program. California Resources Agency and California Environmental 

Protection Agency, Sacramento, California.

Dietrich, W.E., and D.R. Montgomery. 1998. SHALSTAB: A digital terrain model for mapping shallow 

landslide potential. University of California, Berkeley, Geomorphology Research Group, 

Department of Earth and Planetary Science, College of Letters and Science, 307 McCrone 

Hall, Berkeley, California 94720-4757. 

http://socrates.berkeley.edu/~geomorph/shalstab/index.htm

Dietrich, W.E., D. Bellugi, and R. Real de Asua. 2001. Validation of the shallow landslide model, 

SHALSTAB, for forest management. Pages 195-227 in M.S. Wigmosta and S.J. Burges, editors. 

Landuse and watersheds: human influence on hydrology and geomorphology in urban and 

forest areas. Water Science and Application Volume 2. American Geophysical Union Water 

Resources Monograph, Washington, District of Columbia.

Green Diamond Resource Company (GDRCo). 2006. Aquatic habitat conservation plan and 

candidate conservation agreement with assurances. Green Diamond Resource Company. 

Volume 1. 552 p.

Hare, V.C. 2003. Evaluation of a geographic information system model of shallow landsliding in 

Redwood Creek, California. MS Natural Resources Planning and Interpretation, Humboldt 

State University, Arcata, California. 94 pp.

Humboldt State University (HSU). 2007. A landslide study in the Redwood Creek basin, 

northwestern California: effects of the 1997 storm. Tera L. Curry. In partial fulfillment of 

the requirements for the degree Master of Science in Environmental Systems. Geology 

department. 107 p.
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 48

Ligon, F., A.A. Rich, G. Rynearson, D. Thornburgh, and W. Trush. 1999. Report of the scientific 

review panel on California forest practice rules and salmonid habitat. Prepared for the 

Resources Agency of California and the National Marine Fisheries Service. Sacramento, 

California. 92 p. plus appendices.

Madej, M. A., and Ozaki, V. 2009. Persistence of effects of high sediment loading in a salmon-bering 

river, northern California, in James, L.A., Rathburn, S.L., and Whittecar, G.R., eds., 

Management and Restoration of Fluvial Systems with Broad Historical Changes and Human 

Impacts: Geological Society of America Special Paper 451, p. 43-55, doi: 

10.1130/2009.2451(03).

Pitlick, J. 1982. Sediment Routing in Tributaries of the Redwood Creek Basin: Northwestern 

California. Redwood National Park Technical Report Number 8. National Park Service, 

Redwood National Park. Arcata, California. 67 pp. (Out of print)

Redwood Creek Landowners Association. 1998. Alternative Proposal TMDL Strategy for the 

Redwood Creek watershed. Submitted to the North Coast Regional Water Quality Control 

Board October 28, 1998. 38 p.

Redwood Creek Watershed Group. 2006. Integrated watershed strategy for Redwood Creek. 

Available at Redwood National and State Parks, Arcata, Ca. 102 pp.

Redwood National and State Parks. 1997. Draft Redwood Creek Analysis. Redwood National and 

State Parks. 74pp.

Redwood National and State Parks, 2009. Minor Creek Watershed Inventory and Restoration 

Planning Summary Report. Road Assessment Project Contract # P0610549. Redwood 

National and State Parks, Arcata, CA 30pp.

U.S. Department of Interior, National Park Service and California Department of Parks and 

Recreation (NPS-CDPR). 1999. Final General Management Plan/General Plan, 

Environmental Impact Statement/Environmental Impact Report, Vols 1 & 2.

U. S. Environmental Protection Agency. 1998. Total Maximum Daily Load for Sediment Redwood 

Creek, California. U. S. Environmental Protection Agency Region 9. 60 pp.

Weaver, W. E. and D. K. Hagans. 1987. Magnitude, cause and basin response to fluvial erosion, 

Redwood Creek basin, northern California. In: Erosion and Sedimentation. in the Pacific 

Rim (Proceedings of the Corvallis Symposium, August, 1987). IAHS Publ. No. 165. 

Weaver, W.E. and D. K. Hagans. 1994. Handbook for Forest and Ranch Roads. Mendocino County 

Resource Conservation District. 161 pp. 
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 49

GLOSSARY

Culvert - a metal, plastic or concrete pipe set below the road surface. Is used to pass streamflow 

from upslope of the road to downslope of the road. Culverts can also be placed to drain springs and 

inboard ditch flow from the inside to the outside of the road, beyond the outer edge of the road fill, or 

fillslope.

Class I watercourse crossing – a fish bearing stream as defined by the California Forest Practice 

Rules.

Cost-effectiveness – the cost per unit volume of sediment to prevent it from entering a stream, 

commonly expressed as $/yd3 “saved”.

Critical crossing – a haul road crossing at a stream channel that possesses all three of the following 

characteristics: a diversion potential, an undersized culvert and medium to high plug potential.

Critical dip – a broad rolling dip located at a stream crossing that returns streamflow to its natural 

watercourse if the crossing culvert plugs and streamflow overtops the road. It is a broad, gentle, 

permanent dip (low spot) across the road surface that allows passage of vehicles, logging trucks and 

standard logging equipment. They are generally maintenance-free.

Cross-road drain - a deep, abrupt ditch constructed across a road to drain water from the road 

surface and/or inboard ditch. Generally, not drivable and placed at frequent intervals (approx. every 

50 - 100 feet) on permanently closed roads. Compare to rolling dip.

Delivery – the percentage of erosion volume that is actually delivered to a stream. It is used to 

calculate yield. Stream crossings usually have a 100 percent delivery. For landslides the percent 

delivery can be between 0 and 100 percent. Some landslides fail and deliver to a hillslope or 

terrace bench with no delivery to streams (0%). Many landslides deliver 100 percent directly to 

stream channels.

Diversion – a condition originating at a stream crossing, where stream flow overtops the road and 

flows down a road, inboard ditch, or skid trail instead of re-entering its natural watercourse. 

Stream diversions can cause significant gully and landslide erosion.

Diversion potential – normally associated with stream crossings that have continuous road grades 

through the crossing which allow a stream to flow down a road if the crossing culvert plugs and 

streamflow overtops the road. The crossing is not the low point of the road as the road passes over 

the stream channel. Existing diversion potentials can be corrected by installing well-constructed 

critical dips at the crossing so that streamflow returns immediately to its stream channel if 

diversion occurs. Proper crossing construction (grade-breaks, critical dips, minimum fill, properly 

sized culverts) can prevent diversions.
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 50

Decommission – the process of removing road fill or reshaping a road such that erosion and 

sedimentation are minimized. A decommissioned road has all culverts removed, all road fill at 

stream crossings fully excavated and permanent, self-maintaining road surface drainage provided 

by a combination of outsloping, rolling dips or cross road drains. A road may be permanently or 

temporarily decommissioned.

Ditch relief culvert (DRC) – a drainage structure that intercepts and conveys water from the 

inside edge of the road to the outside edge of the road. 

Downspout – normally culvert material bolted and secured to the culvert outlet that conveys water 

down a fillslope to undisturbed ground to prevent surface erosion. Downspouts may be either fullround or half-round.

Erosion potential (EP) – the subjective and relative ranking of the likelihood, not magnitude, of 

erosion at a site during the next major storm. Expressed as “high”, “medium” or “low.”

Erosion volume – is the amount of material that could eroded from a site. It is expressed in cubic 

yards and 0-100 percent may reach a stream. Is used with delivery to calculate yield. 

Extreme erosion potential (EEP) – A subjective assessment of the capability of a potential erosion 

site to erode significantly more volume than the estimated potential erosion volume. Expressed as 

“yes” or “no.” It characterizes a worst case scenario that identifies the potential for an unusually 

large magnitude failure. An example would be a stream diversion that could obliterate inboard 

ditches, relief pipes, and other crossings during a major storm, or a stream crossing or landing that 

could fail catastrophically, scouring hillslopes or channels below. 

Extreme potential yield – The volume of sediment that would be delivered to a stream by a site 

failing under the extreme erosion potential scenario. Expressed in cubic yards.

Fluvial erosion – erosion caused by flowing water. Includes erosion at stream channels, gullies 

and rills. Compare to landslide erosion, which does not include erosion by flowing water.

Ford – a stream crossing that requires a vehicle to drive across and through a stream channel bed. 

There is no fill or drainage structure in a ford crossing.

Inboard ditch – a ditch along the inside edge of the road that collects and conveys road surface 

runoff and spring discharge. The ditch usually conveys runoff to the next culvert or drainage 

structure down the road.

Landing – a location where logs are collected and loaded onto trucks for transport. Landings are 

typically located along haul roads.

Landslide erosion – erosion associated with mass movement of soil or hillslope. Types of 

landslides are debris slides, torrents, earthflows, slumps, rock falls and others. Compare to fluvial 

erosion, which is erosion by flowing water.
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 51

Maintained road – a road that shows evidence of recent maintenance, including cleaning of culvert 

inlets, trash racks, and inboard ditches, grading, rolling dip or waterbar reconstruction, brushing, 

culvert replacement, or reconstruction of fills. Compare to unmaintained road.

Outslope – a road surface that is shaped to slant toward the outside (downslope side) edge of a road. 

The slanted surface naturally disperses surface runoff. A road that is outsloped may or may not be 

drivable depending on the intent of treatment. Outsloped road may or may not have an inboard ditch.

Outsloping – the act of changing a flat or insloped road to an outsloped road. For erosion control

treatments, substantial fill is removed from the outer edge of the road prism, and spread and shaped 

along the inside edge of the road, typically against the cutbank. For surface drainage on active roads, 

the road surface has a mild outslope that is drivable by logging trucks and forms a relatively 

maintenance-free road surface that disperses road surface runoff. 

Potential sediment yield – the larger of the site potential yield and the extreme potential yield (if 

one exists) for a site. Expressed in cubic yards.

Road upgrade – improving a road to current road building standards with the intent of reducing 

erosion from roads. Upgrading includes; replacing rusted, plugged and undersized culverts, 

reshaping roads for proper drainage, constructing critical dips at crossings to prevent stream 

diversions, pulling back steeply perched road or landing fill that can enter a stream, reducing road 

fill volumes at stream crossings and others.

Rolling dip - a broad, shallow, gentle dip (low point) in the road surface that collects road surface 

runoff and conveys it to the outer edge of the road. It can also drain an inboard ditch.

Site potential yield - the expected volume of material that would be delivered to a stream from a 

single erosion site expressed in cubic yards. It is computed by multiplying the erosion volume at a 

site by the percentage delivery to the stream (e.g. 800 yds3 erosion volume x 80% delivery = 640 

yds3 site potential yield). Compare to extreme potential yield and potential sediment yield.

Skid trail crossing - a point where a tractor skid trail crosses a defined stream channel. A drainage 

structure may or may not be present. 

Stream crossing – the point where a road crosses a defined stream channel. The crossing may be 

composed of road fill without a drainage structure or may be composed of buried logs (Humboldt 

crossing), a culvert, a ford, or a bridge.

Stream diversion - a condition where streamflow has been diverted from its natural watercourse.

Unmaintained road – a road that lacks obvious maintenance to culverts, ditches and road surface. 

Culverts may be partially or completely plugged, badly rusted or crushed, outlet flow uncontrolled 

across fillslope or other deficiencies present. Ditches may lack cleaning and vegetation may be 

encroaching the road and road surface. The road may or may not be drivable.

Upgrade – improving a road to current road building standards with the intent of reducing erosion 

from roads. Upgrading includes; replacing rusted, plugged and undersized culverts, reshaping roads 
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL 52

for proper drainage, constructing critical dips at crossings to prevent stream diversions, pulling back 

steeply perched road or landing fill that can enter a stream, reducing road fill volumes at stream 

crossings and others.

Urgency or treatment urgency – a subjective and relative assessment of the need to treat a site to 

prevent erosion. Identified as low, medium or high. A low urgency site typically would survive an 

average winter storm with little threat of experiencing or causing erosion. A medium urgency site 

may experience erosion during an average winter if left untreated. A high urgency site would likely 

erode or cause erosion during an average winter if left untreated.

Waterbar – a shallow ditch or berm constructed across a road or skid trail that drains the road 

surface and/or inboard ditch. It is not a permanent structure as they tend to break down with any 

type of use, including wildlife tramping. They are insufficient to prevent stream diversions at 

crossings.

Yield – the amount of sediment that reaches a stream channel. It is express in cubic yards and may 

be 1-100 percent of the erosion volume.
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL A-1

APPENDIX A

AVERAGE ROAD DENSITY BY SUB-WATERSHED AND INTERFLUVE

Table A1. Average road density by sub-watershed and interfluve.
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL A-2

Table A1. Average road density by sub-watershed and interfluve.

Westside Tributaries Eastside Tributaries

Tributary/Interfluve Name* Area 

sq mi

Total Road 

Miles

Road Density, 

mi/mi2 Tributary/Interfluve Name* Area, sq mi

Total Road 

Miles

Road Density, 

mi/mi2

DC-JC 1.2 0.8 0.7 Coyote 7.9 16.5 2.1

Joplin 0.7 3.7 5.4 CC-JPC 1.2 6.9 5.6

JC-PC 0.8 2.3 3.0 Johnson Prairie 0.6 2.2 3.6

Panther 5.9 30.7 5.2 JPC-GC 0.4 2.5 6.3

PC-GC 1.7 11.1 6.6 Garrett 4.1 21.1 5.1

George 1.1 6.4 5.8 GC-MFC 0.2 1.0 5.2

GC-DVC 1.1 7.6 6.8 Monroe Flat 0.3 1.8 6.0

Dolly Varden 3.4 23.5 7.0 MFC-LC 0.4 2.4 6.0

DVC-LC 0.1 0.1 1.1 Lacks 17.2 82.5 4.8

Lee 0.5 3.1 6.7 LC-SC 0.3 2.5 8.1

LC-GC 0.4 1.5 3.9 Stover 0.9 4.8 5.7

Garcia 1.4 10.1 7.1 SC-RGC 0.8 7.0 8.8

Cashmere 1.3 9.3 6.9 Roaring Gulch 0.7 4.9 7.0

CC-PC 0.8 3.3 4.4 RGC-BC 0.6 4.7 8.2

Pilchuck 1.7 8.8 5.2 Beaver 0.9 4.8 5.6

PC-TUC 0.6 3.6 6.3 BC-MC 0.7 5.2 7.8

Toss-Up 2.7 15.7 5.9 Mill 1.3 7.6 5.7

TUC-JC 0.1 0.4 5.2 MC-MSC 0.1 1.1 13.9

June 0.2 0.9 4.8 Molasses 1.7 12.0 6.9

JC-WC 0.4 2.1 5.4 MSC-MNC 0.8 5.1 6.4

Wiregrass 1.8 9.5 5.3 Moon 1.2 6.7 5.8

WC-LC 0.7 4.8 6.6 MNC-MRC 0.4 4.0 10.1

Loin 0.9 5.0 5.3 Minor 12.9 84.6 6.6

LC-SFC 0.3 1.8 7.0 MRC-SC 1.3 7.8 5.9

Santa Fe 0.8 8.7 10.5 Sweathouse 1.6 9.0 5.6

Greenpoint 0.5 5.0 9.6 SC-CC 0.5 3.3 6.7

GC-LC 1.3 16.8 13.1 Captain 2.1 25.0 12.1

Lupton 5.2 41.1 7.9 CC-NJC 0.3 4.5 16.5

LC-FPC 0.4 3.5 9.5 Negro Joe 1.3 9.5 7.6

Fern Prairie 0.8 6.5 8.2 NJC-WC 0.6 5.3 8.5

FPC-CPC 0.2 1.1 5.6 Windy 1.7 14.2 8.1

Christmas Prairie 0.7 6.9 9.8 WC-STC 0.7 8.3 11.6

CPC-JC 0.2 1.5 8.2 Squirrel Tail 1.6 10.3 6.5

Jena 0.4 4.1 10.7 Emmy Lou 2.6 18.9 7.3

JC-NC 0.3 2.9 8.4 ELC-COMC 0.3 2.8 9.9

Noisy 6.3 46.8 7.4 Cut-Off Meander 0.9 5.1 5.7

NC-CPC 0.5 3.0 6.0 COMC-GC 0.5 5.4 10.2

Cool Springs 1.2 9.5 8.3 Gunrack 1.8 12.3 6.9

CPC-SRC 0.2 0.1 0.9 GC-SC 0.1 0.3 3.0

Six Rivers 1.2 9.2 8.0 SF Gunrack 0.6 1.4 2.5

SRC-AC 0.3 1.7 5.8 Simon 1.7 5.9 3.4

Ayers 0.4 3.6 9.5 SC-MC 0.4 1.3 2.9

AC-HPC 0.2 1.9 9.9 Minon 4.3 22.1 5.2

High Prairie 5.4 40.1 7.4 MC-UPC 0.6 3.8 6.0

HPC-LPC 0.9 8.7 9.8 UPC-BC 0.1 0.9 6.4

Lake Prairie 3.3 18.8 5.6 Upper Panther 2.5 11.2 4.5

LPC-PC 0.8 3.7 4.4 Bradford 3.7 19.3 5.2

Pardee 3.1 23.6 7.6 BC-LGC 0.9 2.6 2.9

PC-DTC 0.1 1.4 9.8 Last Gap 1.6 9.1 5.8

Debris Torrent 0.2 2.0 9.8 LG-LC 0.5 2.4 4.7

DTC-MC 0.7 5.8 8.4 Lineament 0.9 7.8 8.7

Marquette 0.8 6.7 8.7 Headwaters_E 0.2 1.3 7.2

MC-TC 0.0 0.0 0.9 Headwaters_M 2.6 15.1 5.7

Timbo 0.4 3.8 10.7

TC-PC 0.1 1.6 13.6 Totals and Average East Side 94 538 5.7

Powerline 0.6 4.3 6.8 Redwood Creek 2.6 4.3 1.7

PC-SCC 0.1 0.2 2.9

Snow Camp 1.2 8.2 6.8

Smokehouse 0.7 5.8 8.7

Twin Lakes 1.3 9.8 7.8

TC-BC 0.2 1.4 5.7

Burley 0.4 3.0 7.4

BC-TC 0.1 1.3 9.5

Tom 0.4 2.2 5.4

Headwaters_W 0.3 1.7 6.0

Totals and Average West Side 72 494 6.9 Redwood Creek above RNSP 162 1,036 6.4

• Interfluve names are comprised of an abbreviation for tributaries that are immediately adjacent to the interfluve.

• Totals may differ slightly from those shown in other tables due to rounding.

• Road density can be affected by the size of a tributary basin, its ownership, land use, and underlying geology. For example, the road density for 

Lacks Creek is 4.8 mi/mi2 when averaged over the entire sub-basin. However, the road density on the west side of Lacks Creek is about 7 

mi/mi2

, while the road density on the east side is about 4 mi/mi2.
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL B-1

APPENDIX B

FIELD FORM USED BY PCFWWRA AND RNSP
Reviewed by : REDWOOD CREEK BASIN ROAD INVENTORY FORM 

ID No.: Redwood National and State Parks 

 Version 3/27/03

SECTION I: GENERAL SITE INFORMATION

Road Name: Site # Date: By: Watershed: Ownership Year built: Quad ID: Photo# Photo date: Current road condition: Drivable [ Maintained Abandoned Decommissioned ]The road surface is: [ Native Rocked Paved ]Proposed Treatment: [ Maintain Upgrade Decommission ]

SECTION II: FLUVIAL SITE (CROSSINGS, RELIEF CULVERTS, GULLY, ETC.)

FEATURE: [ Stream Xing Skid Xing Swale *DRC Road reach ] SpringPROCESS: None Gully Streambnk/channel eros. Collapsing Fill failure

 Will it debris torrent? Y N M

DRAINAGE STRUCTURE: Bridge *Culvert: *metal *concrete *plastic

 Humboldt Fill Ford Armored fill None Critical dip@xing? Y N Left ditch/road length ft. Right ditch/road length ft.

DIVERSION POTENTIAL: DP? Y N Now diverted Past diverted Rd grade %CONDITION OF FILL: Intact removed % washed-out %CULVERT INLET INFORMATION:

*Diameter in. Headwall height in. Rust line: width _ in. depth _ in.

 Stream class: I, II, III, or IV Upstrm chan: width _ ft; depth _ ft Grade_ % Sediment transport: H M L CMP undersized? Y M N Plug potential: H M L

*Inlet condition: OK Rust/holes Band separation Trash rack Drop inlet *crushed % *plugged %

CULVERT OUTLET INFORMATION:

*Condition: OK Rust/holes Functional downspout %crushed % Shotgun

Fish-outlet drop: now ft. @bankfull ft. Culvert grade %

 Pool dim.: length ft. depth ft. @bankfull: length ft. depth ft.Comments:

 SECTION III: LANDSL

FEATURE: Road reach Landing CutPROCESS: [Slow, deep seated Fast, shallow debris 

SETTING: Streamside: <55% or >55% Swale He

 Distance to stream ft. Slope 

ACTIVITY: Failed in past? : Y N %failed ASSOCIATION(S): Road related Water onto feature 

 SECTION IV: TREATMENTS (C

Critical dip@xing Install culvert Replace culvert NeDrop inlet Flared inlet Trash rack RemoReconstruct fill Excavate fill Ford BArmor fillslope: @inlet ft2; Downstream face Armored fill: sill height ft. sill width 

********** URGENCY: H M L COMP

ROAD REACH TREATMENTSClear/est. IBD ft. Remove IBD ft. Rock ro

Rolling dips: # OS w/out IBD ft. OS wCross-road drains # Ditch relief culvert # 

 SECTION V: FILL AND FUTURE E

Dimensions of landslide or gully: length: ft. wi

 (Use Comment Section below to record dimensions of c

Future erosion volume: yd3 %delivery: 

Erosion Potential: H M L Potentia

Is the treatment likely to control or prevent erosion?: Y Extreme Erosion Potential Volume (yds3): [ <500, 500
✓ EXCAVATION VOLUMES ✓ EQUIPMENT HOURS COMMENT ON TREATMENT: 

 Total excavated (yds3): Excavatror (hrs):  Vol. put back in (yds3): Dozer (hrs):  Vol. removed (yds3): Dump truck (hrs):  Vol. stockpiled (yds3): Grader (hrs):  Vol. endhauled (yds3): Backhoe (hrs):  Dist. endhauled (ft): Labor (hrs):  Exca. prod. rate (yds3/hr): Other: 

Stream Profile through Crossing Xing type: 1, 2, 3, 4 

(begin at top of crossing) (circle one)

Cross Section(s) 

 (begin on left side of cross

Angle (deg) 

(up+, dn-) 

Distance 

(feet) 

Code 

(UES, TOP, IBR, 

OBR, BOT, XS1, 

XS2 ....LES) 

Comments 

XS# Angle 

(deg) 

Distance 

(feet) 

Code 

(LRP, LEC, 

CLP,REC,RRP) 

 0 0 UES, TRN in natural channel 1 0 0 LRP, TRN Ba

DecoErosCulveHum

Site sketch - Site No. : .

Culve
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL C-1

APPENDIX C

REDWOOD CREEK ROAD ASSESSMENT SITE MAPS

There are 16 maps showing roads and assessment site locations for the entire upper watershed. 

The maps may not be included in this printed copy of the report, but are in the electronic version, 

contained on CD at the back of this report. You may request additional copies of the CD or report 

from Darci Short at Redwood National and State Parks: 707-825-5144 or Darci_Short@nps.gov.

Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL D-1

APPENDIX D

PROJECTS AND GRANT FUNDING

Table D-1 shows the cooperative erosion control implementation projects in the upper Redwood 

Creek watershed from 1996 through 2009. Pilot projects prior to 1996 are not shown. Costs for 

erosion control work implemented by landowners outside of the cooperative efforts are not shown. 

Those projects include work associated with timber harvest plans and general road maintenance 

work funded by the landowner. 

Table D-1. Cooperative erosion control projects in the Upper Redwood Creek watershed, 1996 

through 2009. 

Project 

No. Year(s) Watershed Lead Group Funding Source

Landowner Grant TOTAL

4 1996-1997 Garrett RNSP $9,200 $104,500 $113,700 

5 1998 Bradford, etc NRM $16,400 $109,800 $126,200 

6 1999 Lake Prairie, etc. RNSP $94,000 $128,300 $222,300 

7 2001 / 02 Panther, George PCFWWRA $75,000 $197,500 $272,500 

8 2002 / 03 Redwood PCFWWRA $129,800 $214,700 $344,500 

9 2003 / 04 Dolly Varden / K&K PCFWWRA $173,300 $704,500 $877,800 

10 2004 / 06 Coyote Creek (N) PCFWWRA $188,100 $440,900 $629,000 

11 2005 / 06 Redwood PCFWWRA $150,000 $263,900 $413,900 

12 2006 Redwood/Panther PCFWWRA $206,700 $206,700 

13 2006 / 08 Coyote (S) PCFWWRA $95,000 $326,100 $421,100 

14 2006 / 08 Coyote (S) PCFWWRA $464,600 $464,600 

15 2009 Lacks - BLM PCFWWRA $996,000 $676,500 $1,672,500 

Totals $1,926,800 $3,838,000 $5,764,800 

Percent of all Funding 33% 67% 100%

Percent of Funding Through 2009, Omits 

BLM Funded Projects

23% 77% 100%

For all projects, landowners have provided about 33 percent of the total project costs. In 2009, 

BLM provided nearly one million dollars for work on BLM lands. If the BLM project is not factored 

in to the funding totals, landowners have provided about 23 percent of the total funding for 

implementation work.
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL E-1

APPENDIX E

METHODS USED TO ESTIMATE TMDL LOAD REDUCTIONS

BACKGROUND

The Environmental Protection Agency (EPA) has oversight authority of the Clean Water Act (CWA). 

Section 303(d)(1)(A) of the CWA delegates to states the authority to implement provisions of the 

CWA for their waters. It requires states to establish a priority ranking for waters on the 303(d) list 

of impaired waters and establish TMDLs for such waters. If the state does not establish a TMDL, 

then the EPA must develop one. 

Redwood Creek was 303(d) listed as sediment impaired by the California North Coast Regional 

Water Quality Control Board (RWQCB) in 1996, and listed as temperature impaired in 2002. When 

Redwood Creek was listed as sediment impaired, the RWQCB designated the watershed as a high 

priority for development of a sediment TMDL. 

On October 31, 1997, the EPA entered into a consent decree (decree), Pacific Coast Federation of 

Fishermen’s Association, et. al. v. Marcus, (N.D. Cal. No. 95-4474 MHP), which established a 

timetable for development of TMDLs for several watersheds in northwest California. The decree 

required development of a TMDL for Redwood Creek by December 31, 1998. 

On parallel tracks, the EPA and RWQCB both began work on the sediment TMDL for Redwood Creek 

in 1997. The RWQCB completed a draft TMDL with Implementation Plan (RWQCB, 1998) and staff 

report (RWQCB, 1998) in November 1998. An alternative to the RWQCB’s Implementation Plan 

was also developed by private landowners in the Redwood Creek watershed (RCLA, 1998). 

Because neither the RWQCB nor State Water Resources Control Board adopted a TMDL for 

Redwood Creek, the EPA in December 1998 established the TMDL for sediment in order to meet the 

requirements of the decree (EPA, 1998). A sediment TMDL Implementation Plan was never 

adopted by the state. Instead, the RWQCB adopted the Total Maximum Daily Load Implementation 

Policy Statement for Sediment Impaired Receiving Waters in the North Coast Region (Resolution 

No. R1-2004-0087) that relies on existing enforcement and permitting tools to control non-point 

source pollution. 

METHODS 

To estimate the load reductions in relation to TMDL targets requires calculations of load reduction 

in the lower and upper watersheds since 1998. Load reductions are achieved through road 

decommissioning and upgrades. Properly decommissioned roads are maintenance-free and 

sediment sources are removed. In contrast, upgraded roads still contain potential sediment sources 

because the roads are still in place. But, if roads are upgraded correctly, the likelihood of failure 

during large storms will be low. In computing the controllable load reductions (or sediment 

‘saved’; i.e., the amount of sediment prevented from entering a stream by treating the road) since 

establishment of the 1998 TMDL, the total amount of sediment treated through upgrades was 
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL E-2

included, providing the completed work met established standards, and the likelihood of site failure 

after treatment was determined (through inspection) to be low. 

In the lower watershed, one of the Park’s primary goals has been to decommission the hundreds of 

miles of old logging roads that are not needed for park management or visitor use. Because past 

road assessments occurred on roads the Park knew would be decommissioned, the assessments 

only measured the amount of material that would be excavated during road decommissioning. The 

amount of sediment that would be ‘saved’ by road treatments was not estimated. In contrast, road 

assessments in the upper watershed routinely estimated the amount of sediment that would be 

‘saved’ by treating the road. 

Thus, the challenge in estimating the TMDL load reductions that have occurred throughout the 

watershed was estimating the controllable load in park areas that existed in 1998 when the TMDL 

was established and the amount the load has been reduced since 1998. These values were backcalculated by developing correction factors that converted excavation volumes to sediment ‘saved’ 

volumes (load reduction). Described below in more detail, the controllable sediment loads that 

existed in 1998 within park lands and the amount they were reduced (sediment ‘saved’) by work 

completed through 2009 were computed by applying a correction factor of 55 percent to the 

excavation volumes for all stream crossings and a select group of unstable road reach treatments.

For stream crossings, a correction factor was estimated by using data from the upper basin road 

assessment database and queries that computed the average ratio of the estimated potential 

sediment yield volume and estimated site excavation volume. Volumes were based on detailed field 

surveys. The ratio ranged from 46-59 percent and averaged 54 percent. Projects completed in the 

upper watershed were also considered. The ratios for completed projects ranged from 61-85 

percent and averaged 61 percent. Based on those results, we chose a correction factor of 55 

percent of the excavation volume to reflect the sediment ‘saved’ from all stream crossing 

treatments and to ensure a conservative estimate. 

For unstable road reach treatments, we had to consider which and how much of the two primary 

treatments to include. Export Outslope (EOS) treatments remove a great deal (sometimes all) of the 

road bench and, because of site characteristics such as instability, moisture and/or slope steepness, 

excavated road fill cannot be stored locally and must be exported to a stable fillsite. EOS’s generally 

occur in the most unstable geomorphic settings, but the treatment can sometimes be prescribed for 

purposes other than erosion control, as in the case for Outslope (OS) treatments. 

OS treatments store excavated material from the road locally and shape it into the cutbank. While 

some OS treatments were prescribed to prevent sediment delivery, most were prescribed in the 

park to reshape the roads. Doing so improves revegetation, lessens the visual scarring of the road 

on the landscape and ensures permanent surface drainage. Thus, we decided to include most of the 

EOS treatments, but none of the OS treatments when computing sediment savings from unstable 

road reach treatments to ensure a conservative yet reasonable estimate. For EOS treatments, we 

assumed that 75 percent of the EOS treatments were prescribed for erosion control and assumed a 

74 percent delivery rate (HSU 2007) if failure occurred. Combining both assumptions created a 

correction factor of [coincidentally] 55 percent. 
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL E-3

Therefore, for the load reduction in the park, we estimated the total sediment ‘saved’ by summing 

the excavation volumes for all stream crossings and EOS treatments, and multiplying that value by 

55 percent. Based on the treatment of 70 miles of roads, from 1998 to 2009, the load reduction 

averaged about 18,500 yds3 per mile or 28,000 tons per mile. 

Estimating the controllable load for the upper watershed and what remains to be treated was 

straightforward, because the road assessments in the upper watershed routinely estimated the 

amount of sediment that would be ‘saved’ by the road treatments. From road assessments 

completed by PCFWWRA and RNSP, we estimated the total potential sediment yield for all roads in 

the upper watershed at about 2.9 million cubic yards (4.3 million tons). We derived that estimate 

by applying 2,700 yds3 per mile of potential sediment yield (the average potential sediment yield 

from assessed roads) to unassessed roads and believe it is a conservative and reasonable estimate. 

Conditions in the watershed did not change that much between 1998 and the time of road 

assessments, but about 20 miles of new seasonal roads were built. Most were evaluated by the 

road assessments and were built in stable upper hillslope areas. All were built to better standards 

than most of the roads built during earlier years. Because the potential sediment yield from these 

new roads would be a negligible portion of the assessed roads, we chose to use the total potential 

sediment yield from our assessments as the starting point for the 1998 TMDL and load reduction 

calculations. The load reduction in the upper watershed was based on the actual work completed 

through 2009. The load reduction in the upper watershed for the period 1998-2009 was 2,900 

yds3/mile, or about 4,400 tons/mile of road.

The difference between the potential sediment ‘saved’ per mile of road in the lower watershed is six 

times larger than that for the upper watershed. This is not surprising when the nature of these

roads is considered. The lower watershed was dominated by old-growth redwood and was logged 

during an era when large trees ‘needed’ large, wide roads. Mainline roads were built throughout 

what is now park land as two-lane off-highway roads. Spur roads where single lane roads, but still 

generously large and wide. In contrast, the upper watershed was dominated mostly by Douglas-fir 

which are smaller trees. Most of the roads were built with a smaller footprint to one-lane 

standards, resulting in smaller volume fill.
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL F-1

APPENDIX F

RANKING CRITERIA FOR ASSESSED ROADS

Table F-1. Roads ranked by potential sediment yield.

Table F-2. Roads ranked by potential sediment yield per mile.

Table F-3. Roads ranked by cost-effectiveness.

Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL F-2

Table F-1: Roads ranked by potential sediment yield.

Road Name Length 

(mi)

Total 

no. of 

ALL 

Sites

Total no. of 

M to H 

Sites

Potential 

Sediment Yield 

for ALL Sites 

(yds3)

Potential 

Sediment Yield 

for M to H Sites 

(yds3)

Percent of Potential 

Sediment Yield 

Volume for 

M to H Sites

Potential 

Sediment Yield 

per Mile for

M to H Sites 

(yds3/mi)

Total Cost for 

M to H Sites

Cost/Yard 

"Saved"

Dolly Varden 11.8 155 114 109,890 103,954 95% 8,793 $1,234,068 $11.87

Old K&K 8.3 97 35 43,395 33,359 77% 4,042 $307,439 $9.22

LC5000 2.3 26 21 23,659 23,089 98% 10,176 $59,360 $2.57

K&K West 7.9 79 30 37,375 23,063 62% 2,909 $263,580 $11.43

LC1000 6.5 42 27 22,770 20,241 89% 3,134 $191,878 $9.48

1400 4.6 47 32 19,382 17,301 89% 3,753 $96,655 $5.59

PR1100 5.4 69 44 19,033 16,068 84% 2,958 $141,382 $8.80

Old HWY 299 2.5 52 39 16,040 15,064 94% 6,074 $233,836 $15.52

1440 1.5 18 15 15,155 14,588 96% 9,657 $31,314 $2.15

1000 3.9 37 16 14,312 14,050 98% 3,616 $74,023 $5.27

809 1.8 15 13 16,032 12,510 78% 7,032 $156,745 $12.53

808 3.9 40 22 19,766 11,895 60% 3,087 $125,299 $10.53

L2010 4.3 42 27 15,483 11,689 75% 2,750 $136,646 $11.69

MC1000 6.4 82 53 15,313 10,897 71% 1,691 $191,235 $17.55

Mainline 2.7 33 16 13,611 10,585 78% 3,875 $145,608 $13.76

PR1106 0.6 5 5 10,417 10,417 100% 17,639 $31,477 $3.02

UPR-10 4.7 38 24 14,685 10,394 71% 2,197 $126,230 $12.14

R3800 0.9 11 10 9,796 9,774 100% 11,364 $57,576 $5.89

LC4000 2.5 35 24 17,335 9,436 54% 3,849 $85,283 $9.04

1431 1.7 29 22 9,479 9,375 99% 5,626 $95,960 $10.24

RC-2 1.5 25 14 10,122 9,120 90% 6,168 $134,682 $14.77

R1000 2.1 21 13 8,914 8,775 98% 4,164 $33,653 $3.84

Roddiscroft 5.3 55 31 9,195 8,308 90% 1,573 $113,422 $13.65

1410 1.9 23 12 8,125 7,602 94% 3,994 $33,660 $4.43

LC2000 2.6 17 13 8,762 7,591 87% 2,881 $108,119 $14.24

1020 1.7 18 12 8,059 7,544 94% 4,465 $36,317 $4.81

L2171 1.4 16 12 7,884 7,532 96% 5,446 $110,514 $14.67

CR2900 7.2 80 17 18,227 7,509 41% 1,045 $24,776 $3.30

FP500 1.6 29 18 9,014 7,351 82% 4,733 $110,692 $15.06

831 2.1 13 7 7,699 7,338 95% 3,578 $14,821 $2.02

DVA 1.3 18 15 7,480 7,292 97% 5,640 $112,964 $15.49

1140 0.8 15 7 12,616 7,144 57% 9,516 $23,856 $3.34

DVD-1 1.4 12 11 7,102 7,004 99% 5,162 $69,224 $9.88

L1000 3.2 24 15 7,789 6,573 84% 2,031 $70,951 $10.79

L2000-CN 5.4 64 29 7,677 5,754 75% 1,070 $98,520 $17.12
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL F-3

Table F-1: Roads ranked by potential sediment yield.

Road Name Length 

(mi)

Total 

no. of 

ALL 

Sites

Total no. of 

M to H 

Sites

Potential 

Sediment Yield 

for ALL Sites 

(yds3)

Potential 

Sediment Yield 

for M to H Sites 

(yds3)

Percent of Potential 

Sediment Yield 

Volume for

M to H Sites

Potential 

Sediment Yield 

per Mile for 

M to H Sites 

(yds3/mi)

Total Cost for 

M to H Sites

Cost/Yard 

"Saved"

F-1-4 1.6 20 15 6,023 5,431 90% 3,428 $28,719 $5.29

L2011 0.6 10 7 5,822 5,261 90% 8,177 $83,782 $15.92

800H 1.3 20 16 5,736 4,961 86% 3,775 $77,114 $15.54

R3000 3.5 34 17 11,253 4,895 43% 1,379 $38,446 $7.85

R3900 1.7 16 6 12,255 4,508 37% 2,706 $16,304 $3.62

TP1321 1.1 12 7 5,365 4,258 79% 3,713 $39,362 $9.24

1450 3.1 24 16 5,224 4,138 79% 1,321 $45,464 $10.99

BO1315 1.0 8 5 5,084 4,131 81% 4,220 $48,269 $11.68

LC1100 1.1 4 3 4,100 4,003 98% 3,633 $56,894 $14.21

1433 0.5 7 7 3,978 3,978 100% 7,835 $12,109 $3.04

FL1025 0.8 8 7 3,982 3,947 99% 4,671 $17,178 $4.35

820 2.8 15 9 5,559 3,937 71% 1,387 $51,349 $13.04

BO1306 0.4 4 4 3,789 3,789 100% 10,207 $46,725 $12.33

R3500 1.3 14 11 3,755 3,727 99% 2,838 $24,725 $6.63

800G 0.3 2 2 3,726 3,726 100% 12,298 $12,236 $3.28

1150 1.0 15 8 4,640 3,608 78% 3,494 $25,735 $7.13

3C2500 1.9 18 7 5,881 3,554 60% 1,830 $47,799 $13.45

3C2010 0.2 6 5 4,000 3,500 88% 16,972 $49,559 $14.16

LC5005 0.5 3 1 7,074 3,500 49% 7,405 $9,095 $2.60

PR1107 0.7 3 3 3,500 3,500 100% 4,690 $9,900 $2.83

R3810 0.1 2 1 5,000 3,500 70% 43,126 $10,165 $2.90

3C2800 0.8 20 11 4,742 3,429 72% 4,501 $48,288 $14.08

LC-1 8.7 50 18 4,862 3,391 70% 389 $51,327 $15.14

L2010-B 0.1 1 1 3,334 3,334 100% 44,387 $35,350 $10.60

CP1000 1.9 28 7 6,248 3,293 53% 1,704 $51,917 $15.77

D-Line 1.7 22 17 3,445 3,286 95% 1,953 $59,704 $18.17

DVG 0.7 16 16 3,141 3,141 100% 4,658 $42,714 $13.60

SW-1A 3.0 17 11 3,669 3,003 82% 996 $54,248 $18.07

890C 0.8 7 6 3,508 2,963 84% 3,839 $66,185 $22.34

RP1000 3.0 29 17 8,200 2,893 35% 949 $26,994 $9.33

RC-1 1.2 21 11 3,367 2,770 82% 2,253 $33,236 $12.00

808A 1.8 9 9 2,756 2,756 100% 1,530 $18,350 $6.66

Additionally ranked roads available upon request.
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL F-4

Table F-2: Roads ranked by potential sediment yield per mile.

Road Name Length 

(mi)

Total 

no. of 

ALL 

Sites

Total no. of 

M to H 

Sites

Potential 

Sediment Yield 

for ALL Sites 

(yds3)

Potential 

Sediment Yield 

for M to H Sites 

(yds3)

Percent of Potential 

Sediment Yield 

Volume for 

M to H Sites

Potential 

Sediment Yield 

per Mile for 

M to H Sites 

(yds3/mi)

Total Cost for 

M to H Sites

Cost/Yard 

"Saved"

L2010-B 0.1 1 1 3,334 3,334 100% 44,387 $35,350 $10.60

R3810 0.1 2 1 5,000 3,500 70% 43,126 $10,165 $2.90

HP-22 0.0 3 2 1,204 804 67% 25,588 $23,005 $28.60

PR1106 0.6 5 5 10,417 10,417 100% 17,639 $31,477 $3.02

3C2010 0.2 6 5 4,000 3,500 88% 16,972 $49,559 $14.16

HP-21 0.1 1 1 1,014 1,014 100% 15,504 $13,523 $13.34

800G 0.3 2 2 3,726 3,726 100% 12,298 $12,236 $3.28

R3800 0.9 11 10 9,796 9,774 100% 11,364 $57,576 $5.89

BO1306 0.4 4 4 3,789 3,789 100% 10,207 $46,725 $12.33

LC5000 2.3 26 21 23,659 23,089 98% 10,176 $59,360 $2.57

L2173 0.2 3 3 1,845 1,845 100% 9,979 $11,595 $6.28

1440 1.5 18 15 15,155 14,588 96% 9,657 $31,314 $2.15

1140 0.8 15 7 12,616 7,144 57% 9,516 $23,856 $3.34

R1050 0.2 2 1 1,829 1,778 97% 9,405 $11,362 $6.39

Dolly Varden 11.8 155 114 109,890 103,954 95% 8,793 $1,234,068 $11.87

AM-4-1 0.1 1 1 500 500 100% 8,438 $2,712 $5.42

UBR 0.2 3 2 1,775 1,723 97% 8,402 $27,722 $16.09

L2011 0.6 10 7 5,822 5,261 90% 8,177 $83,782 $15.92

L1000-E 0.1 2 2 961 961 100% 8,082 $16,272 $16.93

R4250 0.1 2 2 625 625 100% 8,031 $8,981 $14.38

3C2002 0.1 1 1 1,050 1,050 100% 8,007 $7,458 $7.10

DVJ 0.3 4 2 2,792 2,269 81% 7,882 $16,272 $7.17

1433 0.5 7 7 3,978 3,978 100% 7,835 $12,109 $3.04

LC5005 0.5 3 1 7,074 3,500 49% 7,405 $9,095 $2.60

R2100 0.2 2 2 1,557 1,557 100% 7,402 $4,746 $3.05

N500A 0.2 3 3 1,697 1,697 100% 7,318 $8,348 $4.92

809 1.8 15 13 16,032 12,510 78% 7,032 $156,745 $12.53

R3351 0.1 1 1 750 750 100% 6,544 $1,017 $1.36

RC-2 1.5 25 14 10,122 9,120 90% 6,168 $134,682 $14.77

Old HWY 299 2.5 52 39 16,040 15,064 94% 6,074 $233,836 $15.52

DVA 1.3 18 15 7,480 7,292 97% 5,640 $112,964 $15.49

831A 0.2 3 3 1,237 1,237 100% 5,633 $29,838 $24.12

1431 1.7 29 22 9,479 9,375 99% 5,626 $95,960 $10.24

1220 0.4 6 5 15,170 2,281 15% 5,541 $18,958 $8.31
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL F-5

Table F-2: Roads ranked by potential sediment yield per mile.

Road Name Length 

(mi)

Total 

no. of 

ALL 

Sites

Total no. of 

M to H 

Sites

Potential 

Sediment Yield 

for ALL Sites 

(yds3)

Potential 

Sediment Yield 

for M to H Sites 

(yds3)

Percent of Potential 

Sediment Yield 

Volume for 

M to H Sites

Potential 

Sediment Yield 

per Mile for 

M to H Sites 

(yds3/mi)

Total Cost for 

M to H Sites

Cost/Yard 

"Saved"

PP1010 0.1 1 1 323 323 100% 5,477 $3,729 $11.54

L2171 1.4 16 12 7,884 7,532 96% 5,446 $110,514 $14.67

3C2512 0.3 6 1 3,066 1,500 49% 5,349 $3,729 $2.49

200A 0.3 3 1 1,827 1,689 92% 5,294 $27,120 $16.06

RV4 0.4 6 6 2,068 2,068 100% 5,257 $30,236 $14.62

LC5001 0.1 1 1 750 750 100% 5,246 $2,622 $3.50

DVD-1 1.4 12 11 7,102 7,004 99% 5,162 $69,224 $9.88

LPC-PC-1 0.1 3 1 935 750 80% 5,052 $3,390 $4.52

F-1-4-0 0.2 3 3 1,191 1,191 100% 4,942 $17,930 $15.05

FP500 1.6 29 18 9,014 7,351 82% 4,733 $110,692 $15.06

RP1200 0.3 6 3 1,622 1,413 87% 4,699 $13,560 $9.60

PR1107 0.7 3 3 3,500 3,500 100% 4,690 $9,900 $2.83

FL1025 0.8 8 7 3,982 3,947 99% 4,671 $17,178 $4.35

DVG 0.7 16 16 3,141 3,141 100% 4,658 $42,714 $13.60

3C2800 0.8 20 11 4,742 3,429 72% 4,501 $48,288 $14.08

1020 1.7 18 12 8,059 7,544 94% 4,465 $36,317 $4.81

800F 0.5 2 2 1,945 1,945 100% 4,294 $44,810 $23.04

808D-1 0.1 1 1 295 295 100% 4,261 $5,085 $17.24

BO1315 1.0 8 5 5,084 4,131 81% 4,220 $48,269 $11.68

3C2501 0.3 5 2 2,279 1,101 48% 4,200 $22,130 $20.10

R1000 2.1 21 13 8,914 8,775 98% 4,164 $33,653 $3.84

HRPR-1 0.2 3 2 840 807 96% 4,086 $3,390 $4.20

Old K&K 8.3 97 35 43,395 33,359 77% 4,042 $307,439 $9.22

1410 1.9 23 12 8,125 7,602 94% 3,994 $33,660 $4.43

UPC-BC-2 0.2 1 1 778 778 100% 3,921 $10,848 $13.95

Mainline 2.7 33 16 13,611 10,585 78% 3,875 $145,608 $13.76

LC4000 2.5 35 24 17,335 9,436 54% 3,849 $85,283 $9.04

890C 0.8 7 6 3,508 2,963 84% 3,839 $66,185 $22.34

895 0.6 5 5 2,437 2,437 100% 3,838 $47,405 $19.45

802A 0.1 2 2 247 247 100% 3,833 $2,094 $8.48

800H 1.3 20 16 5,736 4,961 86% 3,775 $77,114 $15.54

R1005 0.4 4 4 1,326 1,326 100% 3,755 $16,606 $12.52

1400 4.6 47 32 19,382 17,301 89% 3,753 $96,655 $5.59

Additionally ranked roads available upon request.
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL F-6

Table F-3: Roads ranked by cost-effectiveness.

Road Name Length 

(mi)

Total 

no. of 

ALL 

Sites

Total no. of 

M to H 

Sites

Potential 

Sediment Yield 

for ALL Sites 

(yds3)

Potential 

Sediment Yield 

for M to H Sites 

(yds3)

Percent of Potential 

Sediment Yield 

Volume for

M to H Sites

Potential 

Sediment Yield 

per Mile for

M to H Sites 

(yds3/mi)

Total Cost for 

M to H Sites

Cost/Yard 

"Saved"

UPC-BC 0.6 4 3 2,194 1,694 77% 2,609 $2,034 $1.20

R3351 0.1 1 1 750 750 100% 6,544 $1,017 $1.36

930 1.7 4 1 750 750 100% 434 $1,119 $1.49

N550A 0.2 1 1 750 750 100% 3,276 $1,356 $1.81

O-8 0.1 1 1 95 95 100% 728 $177 $1.86

O-4-2-3 0.4 5 2 1,468 451 31% 1,169 $908 $2.01

831 2.1 13 7 7,699 7,338 95% 3,578 $14,821 $2.02

1440 1.5 18 15 15,155 14,588 96% 9,657 $31,314 $2.15

800I 0.8 2 2 1,517 1,517 100% 1,913 $3,745 $2.47

3C2512 0.3 6 1 3,066 1,500 49% 5,349 $3,729 $2.49

LC5000 2.3 26 21 23,659 23,089 98% 10,176 $59,360 $2.57

LC5005 0.5 3 1 7,074 3,500 49% 7,405 $9,095 $2.60

R3970 0.2 2 2 910 910 100% 3,741 $2,569 $2.82

PR1107 0.7 3 3 3,500 3,500 100% 4,690 $9,900 $2.83

R3810 0.1 2 1 5,000 3,500 70% 43,126 $10,165 $2.90

PR1106 0.6 5 5 10,417 10,417 100% 17,639 $31,477 $3.02

1433 0.5 7 7 3,978 3,978 100% 7,835 $12,109 $3.04

R2100 0.2 2 2 1,557 1,557 100% 7,402 $4,746 $3.05

800G 0.3 2 2 3,726 3,726 100% 12,298 $12,236 $3.28

CR2900 7.2 80 17 18,227 7,509 41% 1,045 $24,776 $3.30

1140 0.8 15 7 12,616 7,144 57% 9,516 $23,856 $3.34

LC5001 0.1 1 1 750 750 100% 5,246 $2,622 $3.50

R3900 1.7 16 6 12,255 4,508 37% 2,706 $16,304 $3.62

1055 0.3 1 1 89 89 100% 263 $339 $3.81

R1000 2.1 21 13 8,914 8,775 98% 4,164 $33,653 $3.84

RV-1 0.7 3 3 178 178 100% 252 $708 $3.98

HRPR-1 0.2 3 2 840 807 96% 4,086 $3,390 $4.20

PR1104 0.4 1 1 400 400 100% 920 $1,695 $4.24

FL1025 0.8 8 7 3,982 3,947 99% 4,671 $17,178 $4.35

1410 1.9 23 12 8,125 7,602 94% 3,994 $33,660 $4.43

LPC-PC-1 0.1 3 1 935 750 80% 5,052 $3,390 $4.52

N750 0.3 2 1 426 371 87% 1,267 $1,695 $4.57

CP1210 1.4 19 1 6,324 686 11% 491 $3,210 $4.68

1020 1.7 18 12 8,059 7,544 94% 4,465 $36,317 $4.81

N500A 0.2 3 3 1,697 1,697 100% 7,318 $8,348 $4.92
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL F-7

Table F-3: Roads ranked by cost-effectiveness.

Road Name Length 

(mi)

Total 

no. of 

ALL 

Sites

Total no. of 

M to H 

Sites

Potential 

Sediment Yield 

for ALL Sites 

(yds3)

Potential 

Sediment Yield 

for M to H Sites 

(yds3)

Percent of Potential 

Sediment Yield 

Volume for

M to H Sites

Potential 

Sediment Yield 

per Mile for 

M to H Sites 

(yds3/mi)

Total Cost for 

M to H Sites

Cost/Yard 

"Saved"

LC-7 0.7 6 2 1,611 649 40% 942 $3,216 $4.96

R5000 1.4 9 3 1,474 814 55% 569 $4,168 $5.12

L2000 0.5 10 3 1,403 1,293 92% 2,484 $6,734 $5.21

1000 3.9 37 16 14,312 14,050 98% 3,616 $74,023 $5.27

F-1-4 1.6 20 15 6,023 5,431 90% 3,428 $28,719 $5.29

801 1.3 4 2 503 497 99% 394 $2,675 $5.38

AM-4-1 0.1 1 1 500 500 100% 8,438 $2,712 $5.42

N770 0.6 4 4 1,645 1,645 100% 2,726 $9,079 $5.52

1400 4.6 47 32 19,382 17,301 89% 3,753 $96,655 $5.59

LC2 0.3 4 4 923 923 100% 3,052 $5,238 $5.67

N500C 1.3 3 2 69 69 100% 55 $392 $5.68

R3800 0.9 11 10 9,796 9,774 100% 11,364 $57,576 $5.89

R-77 0.1 1 1 30 30 100% 226 $177 $5.90

3C2810 0.5 3 1 783 500 64% 976 $3,051 $6.10

L2173 0.2 3 3 1,845 1,845 100% 9,979 $11,595 $6.28

R1050 0.2 2 1 1,829 1,778 97% 9,405 $11,362 $6.39

RP900 0.7 5 3 1,091 1,082 99% 1,485 $7,060 $6.52

R3500 1.3 14 11 3,755 3,727 99% 2,838 $24,725 $6.63

808A 1.8 9 9 2,756 2,756 100% 1,530 $18,350 $6.66

R3200 1.3 13 5 1,338 498 37% 382 $3,412 $6.85

R3350 0.3 5 3 215 145 67% 548 $1,017 $7.03

DVM 1.4 10 8 2,082 2,017 97% 1,435 $14,249 $7.06

3C2002 0.1 1 1 1,050 1,050 100% 8,007 $7,458 $7.10

1150 1.0 15 8 4,640 3,608 78% 3,494 $25,735 $7.13

HP-31 0.3 1 1 306 306 100% 930 $2,185 $7.15

DVJ 0.3 4 2 2,792 2,269 81% 7,882 $16,272 $7.17

C1400 0.6 1 1 233 233 100% 394 $1,695 $7.27

FL1030 0.3 2 1 252 139 55% 495 $1,070 $7.70

R3000 3.5 34 17 11,253 4,895 43% 1,379 $38,446 $7.85

FP1000 1.5 18 3 151 85 56% 57 $678 $7.98

DVC 0.1 2 2 331 331 100% 2,511 $2,712 $8.20

800H-1 0.1 2 2 391 391 100% 2,839 $3,210 $8.21

Additionally ranked roads available upon request. 
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL G-1

APPENDIX G

Sub-Watershed Ranking with Weighting Values for Risk Analysis

Table G-1. Sub-watersheds ranked by total potential sediment yield.

Table G-2. Sub-watersheds ranked by number of critical crossings in each sub-watershed.

Table G-3. Sub-watersheds ranked by the number of Shalstab sites in each sub-watershed.
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL G-2

SUB-WATERSHED RANKING WITH WEIGHTING VALUES FOR RISK ANALYSIS

This appendix contains the definition of terms and explanation of weighting values for the risk 

analyses.

Yield –describes the total potential sediment yield in each sub-watershed. It integrates nicely into a 

risk analysis because it quantifies the amount of sediment that can potentially impact aquatic 

habitat and water quality. Yield is expressed in cubic yards (yds3). 

In this analysis, potential sediment yield is always the larger of site potential yield or the extreme 

potential yield for each site. The site potential yield was estimated for each site in the field, and 

represents the volume of material that can potentially erode and be delivered to a stream during a 

large storm. The extreme potential yield is the volume of sediment that can potentially be delivered 

during an extreme erosional event (e.g., a debris torrent initiating at a stream crossing), when the 

possibility for an extreme event had been identified in the field. The extreme potential yield is 

always larger than the site potential yield. The potential sediment yield for all sites in a subwatershed was summed and sorted from the highest to lowest values. Weighting values (odd 

values from 1-9) were assigned to each sub-watershed based on the 20 percent breaks for 

cumulative potential sediment yield.

Table G-1 ranks each sub-watershed by total potential sediment yield and assigns a weighting value 

for the risk analysis. Potential sediment yield ranged from 479 yds3 in Six Rivers Creek to more 

than 142,300 yds3 in Lacks Creek which is the largest sub-watershed in the upper Redwood Creek 

watershed. Minor Creek is the next largest sub-watershed in the upper Redwood Creek watershed. 

When compared to Lacks Creek, it is about 30 percent smaller, but has less than half of the potential 

sediment yield. Because the potential sediment yield for Lacks Creek was nearly twice as much as 

Minor Creek’s value, Lacks Creek was not considered in the range of values when weighting values 

were assigned. Excluding Lacks Creek, the average potential sediment yield was about 13,930 yds3

and the median yield was about 8,900 yds3. Only sites that had medium to high erosion potentials 

were considered, because low sites were considered relatively stable.

Critical crossings (CXings) – have a diversion potential, an undersized culvert for a 100-year flood, 

and a medium to high plug potential. They are road-stream crossings that are the most likely 

crossings to divert streams from their natural watercourses, and represent a potentially significant 

source of sediment from erosion that occurs along a road and/or on the hillslope that receives the 

diverted streamflow. The risk analysis considers how many critical crossings are found in each 

sub-watershed. The potential volume of sediment from the failure of a critical crossing cannot be 

measured before failure occurs and volume estimates would be highly speculative. However, 

studies performed in Redwood Creek show that stream diversions can lead to significant gully and 

landslide erosion (Best and others, 1995; Weaver and Hagans, 1987).

Diversion and culvert plug potentials were evaluated in the field. Culvert diameter sizing was 

based on field evaluations and the use of standard culvert sizing methods for the 100-year storm. 

For each sub-watershed, the number of critical crossings was summed and then totals were sorted 
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL G-3

from high to low values. Weighting values for each sub-watershed were then assigned based on the 

20% break in the cumulative number of CXings.

Table G-2 ranks each sub-watershed by the number of critical crossings found in each subwatershed, and assigns a weighting value for each sub-watershed. Critical crossings ranged from 

one crossing in seven of the sub-watersheds to 41 crossings in Lacks Creek. The average and 

median number of CXings per sub-watershed was seven and three, respectively.

Shalstab – The risk analysis considers how many of the sites evaluated in a sub-watershed fall 

within a potentially unstable zone based on Shalstab interpretation of the landscape. Shalstab is a 

GIS-based model used for mapping the potential of shallow slope instabilities (Dietrich et al., 2001; 

Dietrich and Montgomery, 1998) and applied to the Redwood Creek watershed (Hare, 2003). 

Model output has been used extensively in the Redwood Creek watershed during the field review of 

proposed timber harvest plans. While not precise, model output has been field evaluated 

throughout the watershed and has shown good correlation with actual geomorphic conditions.

Shalstab output described here are results from a model run on a 10 meter drainage enforced 

Digital Elevation Model (DEM) of the entire Redwood Creek Basin. The DEMs were created at 

Redwood National and State Parks using the TOPOGRID function in ArcInfo with a contour 

crenulated drainage network for drainage enforcement. Parameters used to run the model are 

those suggested for regional applications (phi=45 degrees, and soil density = 1700 kg/m3) (Dietrich 

and Montgomery, 1998). For the purpose of this analysis, Shalstab values of Log(q/T) <= -2.8 

defined the slope stability classes where shallow landsliding could occur. The number of potential 

Shalstab sites in each sub-watershed was summed and the totals sorted from high to low values. 

Weighting values for each sub-watershed were then assigned based on the 20% break in the 

cumulative number of Shalstab sites.

Table G-3 ranks each sub-watershed by the number of Shalstab sites found in each sub-watershed, 

and assigns a weighting value for each sub-watershed. The number of Shalstab sites in each subwatershed ranged from zero in several sub-watersheds to 59 in Lacks Creek. Of the 42 subwatersheds considered, more than half had fewer than two Shalstab sites in the sub-watershed. 

The average and median number of Shalstab sites were seven and three, respectively.
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL G-4

Table G-1. Sub-watersheds ranked by total potential sediment yield. 

Sub-Watershed Acres %Roads

Evaluated

Total Potential Sediment Yield Weighting

(yds3) (%CumYield) Value

Lacks 10,977 85% 142,333 outlier 9

Minor 8,248 87% 73,535 100% 9

Dolly Varden 2,151 92% 44,327 87% 9

Toss-Up 1,709 97% 43,662 79% 7

Lupton 3,329 62% 35,637 72% 7

Wiregrass 1,153 92% 34,515 65% 7

Coyote 5,043 57% 30,159 59% 5

Pilchuck 1,086 92% 24,398 54% 5

Panther 3,800 95% 21,767 50% 5

Garcia 905 90% 20,627 46% 5

Noisy 4,030 73% 19,326 42% 5

Garrett 2,643 62% 18,688 39% 3

Lee 292 100% 17,546 36% 3

Headwaters_M 1,688 72% 16,112 33% 3

Lake Prairie 2,144 82% 14,035 30% 3

Loin 601 81% 12,515 27% 3

Negro Joe 806 72% 12,380 25% 3

Twin Lakes 811 90% 11,875 23% 3

Pardee 1,985 68% 11,280 21% 3

Stover 544 56% 9,885 19% 1

Smokehouse 426 74% 9,210 17% 1

Powerline 408 94% 8,874 16% 1

Timbo 229 94% 8,769 14% 1

George 699 100% 8,145 13% 1

High Prairie 3,476 50% 8,011 11% 1

Johnson Prairie 386 87% 7,338 10% 1

Fern Prairie 509 73% 7,310 8% 1

Snow Camp 773 66% 6,262 7% 1

Cashmere 861 80% 5,554 6% 1

Tom 259 93% 4,067 5% 1

Headwaters_W 179 52% 3,740 4% 1

Cool Springs 737 45% 3,592 4% 1

Christmas Prairie 455 73% 3,033 3% 1

Santa Fe 530 65% 3,003 3% 1

Marquette 492 91% 2,747 2% 1

Jena 246 47% 2,715 2% 1

Burley 255 91% 2,564 1% 1

June 125 100% 1,694 1% 1

Joplin 441 90% 657 0% 1

Debris Torrent 129 91% 559 0% 1

Ayers 242 97% 511 0% 1

Six Rivers 741 57% 479 0% 1
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL G-5

Table G-2. Sub-watersheds ranked by number of critical crossings in each sub-watershed.

Sub-Watershed Miles of Roads #CXs %Cum# of 

CXings

Weighting 

2004 %Evaluated 2010 Value

Lacks 90.0 85% 82.5 41 100% 9

Minor 84.6 87% 84.6 30 85% 9

Negro Joe 9.5 72% 9.5 20 74% 7

Dolly Varden 28.2 92% 23.5 20 67% 7

Coyote 48.7 57% 16.5 17 59% 5

Noisy 51.2 73% 46.8 17 53% 5

Johnson Prairie 2.2 87% 2.2 12 47% 5

Garrett 22.0 62% 21.1 11 43% 5

Lupton 43.6 62% 41.1 9 39% 3

Panther 40.4 95% 30.7 9 35% 3

Powerline 4.6 94% 4.3 8 32% 3

Garcia 10.1 90% 10.1 5 29% 3

Toss-Up 16.6 97% 15.7 5 27% 3

Pardee 26.4 68% 23.6 5 26% 3

Wiregrass 9.7 92% 9.5 5 24% 3

George 7.3 100% 6.4 5 22% 3

Snow Camp 8.3 66% 8.2 5 20% 3

Burley 3.2 91% 3.0 4 18% 1

Tom 2.7 93% 2.2 4 17% 1

Stover 4.8 56% 4.8 3 15% 1

Cool Springs 9.6 45% 9.5 3 14% 1

Twin Lakes 9.8 90% 9.8 3 13% 1

Christmas Prairie 6.9 73% 6.9 3 12% 1

Six Rivers 9.2 57% 9.2 3 11% 1

Smokehouse 5.8 74% 5.8 3 10% 1

Timbo 4.0 94% 3.8 3 9% 1

Debris Torrent 2.0 91% 2.0 2 8% 1

Loin 5.4 81% 5.0 2 7% 1

Fern Prairie 6.5 73% 6.5 2 6% 1

Headwaters_M 16.4 74% 15.1 2 5% 1

Joplin 4.7 90% 3.7 2 5% 1

Lee 3.3 100% 3.1 2 4% 1

Pilchuck 9.3 92% 8.8 2 3% 1

Headwaters_W 1.7 52% 1.7 1 3% 1

High Prairie 42.0 50% 40.1 1 2% 1

Jena 4.1 47% 4.1 1 2% 1

June 0.9 100% 0.9 1 1% 1

Marquette 6.7 91% 6.7 1 1% 1

Santa Fe 9.3 65% 8.7 1 1% 1

Lake Prairie 25.5 82% 18.8 1 0% 1
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL G-6

Table G-3. Sub-watersheds ranked by the number of Shalstab sites in each sub-watershed.

Sub-Watershed

Miles of Roads Number of 

Shalstab 

Sites

%Cumulative 

Number of 

Shalstab Sites

Weighting

2004 % Evaluated 2010 Value

Lacks 90.0 85% 82.5 59 100% 9

Minor 84.6 87% 84.6 53 81% 9

Toss-Up 16.6 97% 15.7 27 63% 7

Wiregrass 9.7 92% 9.5 17 54% 5

Pilchuck 9.3 92% 8.8 15 49% 5

Lupton 43.6 62% 41.1 14 44% 5

Panther 40.4 95% 30.7 12 39% 3

Lake Prairie 25.5 82% 18.8 11 35% 3

Garcia 10.1 90% 10.1 9 31% 3

Negro Joe 9.5 72% 9.5 9 28% 3

Pardee 26.4 68% 23.6 8 25% 3

Dolly Varden 28.2 92% 23.5 8 23% 3

Coyote 48.7 57% 16.5 8 20% 3

Timbo 4.0 94% 3.8 6 17% 1

Lee 3.3 100% 3.1 5 16% 1

George 7.3 100% 6.4 5 14% 1

Garrett 22.0 62% 21.1 4 12% 1

June 0.9 100% 0.9 4 11% 1

Cashmere 9.3 80% 9.3 3 10% 1

High Prairie 42.0 50% 40.1 3 9% 1

Joplin 4.7 90% 3.7 3 8% 1

Debris Torrent 2.0 91% 2.0 3 7% 1

Twin Lakes 9.8 90% 9.8 3 6% 1

Loin 5.4 81% 5.0 3 5% 1

Headwaters_M 16.4 74% 15.1 2 4% 1

Noisy 51.2 73% 46.8 2 3% 1

Marquette 6.7 91% 6.7 2 2% 1

Stover 4.8 56% 4.8 2 2% 1

Powerline 4.6 94% 4.3 1 1% 1

Christmas Prairie 6.9 73% 6.9 1 1% 1

Six Rivers 9.2 57% 9.2 1 0% 1

Fern Prairie 6.5 73% 6.5 0 0% 0

Smokehouse 5.8 74% 5.8 0 0% 0

Santa Fe 9.3 65% 8.7 0 0% 0

Headwaters_W 1.7 52% 1.7 0 0% 0

Jena 4.1 47% 4.1 0 0% 0

Cool Springs 9.6 45% 9.5 0 0% 0

Burley 3.2 91% 3.0 0 0% 0

Tom 2.7 93% 2.2 0 0% 0

Johnson Prairie 2.2 87% 2.2 0 0% 0

Ayers 3.8 97% 3.6 0 0% 0
Redwood Creek – Progress Report on Erosion Control Work and Sediment TMDL H-1

APPENDIX H

SALMONID DISTRIBUTION IN THE REDWOOD CREEK WATERSHED

Figure H-1. Anadromous salmonid distribution by sub-watershed.
Lacks

Minor

Garrett

Stover

Bradford

Coyote

Johnson Prairie

Molasses

Devils

Panther

George

Dolly Varden

Lee

Garcia

Cashmere

Pilchuck

Toss-Up

Sweathouse

Captain

Negro Joe

Windy

Squirrel Tail

Emmy Lou

Cut-Off Meander

Gunrack

Simon

Minon

June

Wiregrass

Loin

Santa Fe

Greenpoint

Lupton

Fern Prairie

Christmas Prairie

Jena

Noisy

Cool Springs

Six Rivers

Upper Panther

Last Gap

Lineament

Headwaters_E

Headwaters_M

High Prairie

Lake Prairie

Pardee

Marquette

Timbo

Powerline

Snow Camp

Smokehouse

Twin Lakes

Burley

Tom

Headwaters_W

Debris Torrent

Ayers

Beaver

Anadromous Salmonid

Distribution by Sub-Watershed

Upper Redwood Creek Watershed

*The distribution of anadromous salmonids is shown

by sub-watershed as documented by stream survey data

collected since 1965. This map does not show the

historic range of individual species nor is it a comprehensive

record of fish presence. This is particularly true with

respect to Chinook as available survey data is often from

the summer months when Chinook are not in the river system.

Likewise, indicated presence of a species within a sub-watershed

does not imply fish access to the entire channel network within

the sub-watershed - in most cases access is limited to the

lower reaches of the sub-watershed. Information is from

the stream survey data referenced below:

Anderson, D.G. 1988.

Brown, R.A. 1988.

California Department of Fish and Game, 2011.

California Department of Fish and Game, 2002.

California Department of Fish and Game, 1965.

California Department of Fish and Game, 1966.

Redwood National and State Parks, 2001.

Source: RNSP GIS - N:\GIS_Maps\user_maps\60_UBErosionPreventionRanking\2010 Update

Compiled: February, 2011

0 1 2 4 6 8

Miles

Anadromous Salmonid Distribution

by Sub-Watershed*

Watershed divides

Streams (1:24k)

Coho, Chinook, Cutthroat and Steelhead

Coho, Chinook and Steelhead

Coho, Cutthroat and Steelhead

Coho and Steelhead

Cutthroat and Steelhead

Steelhead

No data available