PROJECT ASSESSMENT AND EVALUATION PLAN (PAEP)
Navarro Watershed Road Sediment Reduction Project
Agreement Number 07-541-550-0, Component Project #2.12
1.
Project Summary
A.
Funding Program:
B.
Project Description and Problem Statement
Proposition 50 Integrated Regional Water Management
The Navarro River watershed covers approximately 315 square miles and is the largest
coastal watershed in Mendocino County. In 1998 The Navarro Watershed Restoration
Plan (NWRP) was adopted by the Mendocino County Board of Supervisors. Developed
and coordinated by the State Coastal Conservancy, Mendocino County Water Agency,
Anderson Valley Land Trust, and local stakeholders--the specific recommendations
include: 1) increase the frequency and depth of pool habitat; 2) decrease summer
stream temperatures; and 3) reduce accelerated sediment production (NWRP, p. xxvii).
High-priority sub-basins were identified in order to direct restoration efforts in the
210,000-acre watershed towards improving water quality and restoring salmonid habitat,
with a particular emphasis on streams which currently, or have the future potential to,
support coho salmon. The State Regional Water Resources Control Board--under
Section 303(d) of the Clean Water Act has also identified the Navarro as an impaired
river system for temperature and sediment. A Total Maximum Daily Load Technical
support document guides implementation efforts to reduce sediment delivery in the
Navarro system. The NWRP identified upslope conditions and, specifically, erosion from
unpaved logging, ranch, and residential roads as a significant contributor to
sedimentation problems in the Navarro system. This project element will focus on
Rancheria Creek and Indian Creek, tributaries to the Mainstem Navarro River, and
representing two of the five major sub-basins of the Navarro River watershed.
The Mendocino County Resource Conservation District (RCD) will implement road
sediment reduction measures on Indian Creek and Rancheria Creek through the
IRWMP-Prop 50 Grant. Matching funds will also be used to implement road sediment
reduction measures in the Mainstem and North Fork Navarro River sub-basins. Both the
NWRP and TMDL Technical Support Document indicate that the most controllable
sources of sediment to the Navarro system are from rural, unimproved roads. This
project will upgrade 18.5 miles of ranch roads in the Rancheria and Indian Creek sub
basins using progressive design and maintenance methods outlined in the Handbook of
Forest and Ranch Roads (Hagans & Weaver, 1994) and the California Salmonid Stream
Habitat Manual, Chapter 10 (Third Edition). The Project will prevent approximately
23,972 cubic yards of sediment from delivering to the Navarro River watershed. Stream
crossings will be designed to accommodate 100-year storm event flows.
The overall project goal is to apply erosion prevention treatments on 37 miles of
unimproved ranch roads to prevent 48,535 cubic yards of sediment from entering
streams. To reach this goal, two funding streams will be applied: 1) NCIRWM-Prop50
administered by the County of Humboldt under this grant agreement; and 2) 319(h)
administered through the North Coast Regional Water Quality Control Board. This
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project element addresses 18.5 miles of road and prevents an estimated 23,972 cubic
yards of sediment from entering streams. A total of 164 stream crossings and 136 road
segments will be upgraded for the 100 year storm event. The balance of the road
sediment reduction improvements is addressed through the 319(h) grant. These project
elements will run concurrently, but are managed separately by the RCD.
The implementation will follow prescriptions described in the corresponding road
assessment for each property, which include: 1) Replace, install, reinstall and/or
minimize diversion potential and erosion at stream crossings with culverts sized for 100year storm events; 2) Outslope roads, remove outboard berms, fill inboard ditches, and
install rolling dips along each identified road segment; and 3) Clean culverts and install
trash racks to prevents culverts from plugging (where applicable).
1. To prevent an estimated potential 23, 972 cubic yards of sediment from delivering to
streams over a ten-year period, the project will upgrade approximately 82 stream
crossings with culverts sized for 100-year storm events: Road upgrading involves a
variety of treatments used to make a road more resilient to large storms and flood flows.
The most important of these include stream crossing upgrading (especially culvert upsizing to accommodate the 100-year storm flow and debris in transport, and to eliminate
stream diversion potential), removal of unstable sidecast and fill materials from steep
slopes, and the application of drainage techniques to improve dispersion of road surface
runoff.
STREAM CROSSINGS
 all stream crossings have a drainage structure designed for the 100-year flow
 stream crossings have no diversion potential (functional critical dips are in place)
 stream crossing inlets have low plug potential (trash barriers & graded drainage)
 stream crossing outlets are protected from erosion (extended, transported or
dissipated)
 culvert inlet, outlet and bottom are open and in sound condition
 undersized culverts in deep fills (> backhoe reach) have emergency overflow culvert
 bridges have stable, non-eroding abutments & do not significantly restrict design flood
 fills are stable (unstable fills are removed or stabilized)
 road surfaces and ditches are “disconnected” from streams and stream crossing
culverts
 decommissioned roads have all stream crossings completely excavated to original
grade
 Class 1 (fish) streams accommodate fish passage
2. To prevent an estimated potential of 23, 972 cubic yards of sediment from delivering
to streams over a ten-year period, the project will also outslope approximately 4568 feet
of road, remove an estimated 372 feet of berm, fill an estimated 305 feet of inboard
ditch, and build approximately 189 rolling dips along each identified road segment:
Road drainage techniques that will be applied, include berm removal, road outsloping,
rolling dip construction, and/or the installation of ditch relief culverts. The goal of all
treatments is to make the road as “hydrologically invisible” as is possible; that is to
disconnect the road from the stream system and thereby preserve aquatic habitat.
ROAD AND LANDING FILLS
 unstable and potentially unstable road and landing fills are excavated (removed)
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 excavated spoil is placed in locations where eroded material will not enter a stream
 excavated spoil is placed where it will not cause a slope failure or landslide
ROAD SURFACE DRAINAGE
 road surfaces and ditches are “disconnected” from streams and stream crossing
culverts
 ditches are drained frequently by functional rolling dips or ditch relief culverts
 outflow from ditch relief culverts does not discharge to streams
 gullies (including those below ditch relief culverts) are dewatered to the extent possible
 ditches do not discharge (through culverts or rolling dips) onto active or potential
landslides
 decommissioned roads have permanent road surface drainage and do not rely on
ditches
3. To prevent an estimated potential of 23, 972 cubic yards of sediment from delivering
to streams over a ten-year period, the project will clean culverts where applicable and
install approximately 5 trash racks to prevent plugging:
 stream crossing inlets have low plug potential (trash barriers & graded drainage)
 culvert inlet, outlet and bottom are open and in sound condition
Problem Statement:
Road-related erosion from Rancheria Creek contributes an estimated 155,700 tons of
sediment into the Navarro River, annually. Road-related erosion from Indian Creek
contributes an estimated 41,500 tons of sediment into the system. Together these two
sub basins account for 40 percent of the road-related sediment delivered annually into
the Navarro system (NWRP, pp. 3-4, 5-8, 5-10). Both of the road systems addressed by
this proposal have high road densities, and if left untreated, have the potential to
contribute high amounts of sediment into Rancheria Creek and Indian Creek, impacting
water quality and salmonid spawning and rearing habitat.
The Mendocino County Resource Conservation District will use the Navarro Watershed
Permit Coordination Program for CEQA, DFG 1600, Army Corps 404, and RWQCB 401
permits. If needed, the MCRCD will work with regulatory agencies to obtain the
conventional permits for the remainder of the project sites. These sites may include
those having perennial wet crossings—typically in the western portion of the watershed,
potentially in the Indian Creek upland areas. We do not anticipate any future problems
with permitting; the process was initiated upon notification of funding. Projects that met
requirements for Coordinated Permitting had CEQA, DFG Streambank Alteration
Agreements, 401 and 404 covered by that program by November 2007. The earliest
start date for actual implementation is June 15th, 2008 at which point the RCD will need
to ensure that nesting birds are not present in the worksite.
Forest roads can be storm-proofed by one of two methods: upgrading or
decommissioning (Weaver and Hagans, 1994). Upgraded roads are kept open and are
inspected and maintained. Their drainage facilities and fills are designed or treated to
accommodate or withstand the 100-year storm. In contrast, properly decommissioned
roads are closed and no longer require maintenance.
For the sake of simplicity, specific details and drawings for each sediment treatment site
are available for field review and evaluation by the Department of Fish and Game. For
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each site proposed for treatment, there is a detailed field data form describing site
conditions, risk of future erosion, and details of the proposed treatment. For all streamcrossing sites, we have prepared sketch maps, as well as cross sections and profile
surveys, and design drawings for each proposed excavation.
The specific erosion control and erosion prevention plan for these routes includes (for
each site proposed for treatment) the recommended treatment prescription, treatment
specifications, needed materials and equipment (including heavy equipment), estimated
equipment times (hours), needed labor, estimated costs to complete the project and a
quantitative evaluation of treatment cost-effectiveness. This implementation information,
as well as the expected benefit (in yds3 “saved” from entering the stream system) is
detailed for each ownership in site-specific treatment tables. All proposed treatments for
specific sites, whether roads, road segments, or other specific sites, have been
discussed with the landowner and land manager to ensure they are in conformance with
existing or future management plans for the watershed areas.
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Project 125 – Navarro Watershed Road Sediment Reduction Project
Project Performance Measures Table – Navarro Watershed Road Sediment
Reduction Project (125)
A
Project
Goals
Erosion
Control and
Prevention
in Rancheria
Creek and
Indian Creek
Watersheds
Reduction of
sediment to
Rancheria
and Indian
Creek
Watersheds
B
C
D
E
Outcome
Indicators
Measurement
Tools and
Methods
Sediment
pollution
reduction
1. Upgrade 18.5
miles of
unimproved
ranch roads
2. Five
landowners
voluntarily
implementing
sediment-related
BMP’s.
Estimated
23,972 cu.
yards of
sediment
prevented
from
entering
streams
over 10 year
period
DFG’s CA
Salmonid
Stream Habitat
Restoration
Manual,
Chapter 10
Photomonitoring
Reduce 23,
972 cubic
yards of
sediment
delivery to
streams by
2017.
Remove
road
erosion
potential
from
Rancheria
and Indian
Creek
Watersheds
1. Estimated 82
crossings
upgraded to 100yr event
2. Estimated
4568 ft of road
out-sloped
3. remove and
estimated 372 ft
of berm
4. fill estimated
305 ft of inboard
ditch
5. build
estimated 189
rolling dips
6. install 5 trash
racks
7. Estimated 50
culverts
installed/replaced
100%
reduction in
culvert
failure
during
annual
storm
events for
20 years
Estimated
23,972 cu
yards of
sediment
prevented
from
entering
streams
over 10 year
period.
Handbook for
Forest and
Ranch Roads,
Hagans and
Weaver, 1994
DFG’s CA
Salmonid
Stream Habitat
Restoration
Manual,
Chapter 10
Photomonitoring
Reduce
sediment
delivery to
streams by
23,972 cu
yards in 10
years – to
achieve
Navarro
watershed
TMDL TSD
by 2017
Desired
Output
Outcomes Indicators
F
Targets
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Project Performance Measures Table – Navarro Watershed Road Sediment
Reduction Project (125)
A
Project
Goals
Contribute
to
achievement
of Navarro
Watershed
TMDL goals
B
C
Desired
Output
Outcomes Indicators
Reduce
road
surface
erosion per
Navarro
Watershed
Restoration
Plan
1. Estimated 136
road segments
upgraded
2. Five
landowners
voluntarily
implementing
sediment related
BMP’s.
D
E
Outcome
Indicators
Measurement
Tools and
Methods
Targets
DFG’s CA
Salmonid
Stream Habitat
Restoration
Manual,
Chapter 10
Photomonitoring
Reduce
sediment
delivery to
streams by
23,972 cubic
yards per
year – to help
achieve
Navarro
watershed
TMDL TSD
by 2017
100%
reduction in
culvert
failure
during
annual
storm
events for
20 years in
Rancheria
and Indian
Creeks,
tributaries to
the Navarro
Estimated
23,972 cu
yards of
sediment
prevented
from
entering
streams
over 10 year
period, in
Rancheria
and Indian
Creeks,
tributaries to
the Navarro.
F
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