The Bowron River Watershed: A Landscape Level Assessment
of the Post-Salvage Change in Stream and Riparian Function
Overview
In 1975, a spruce bark beetle outbreak occurred in the Bowron River watershed. In response to
the infestation, large scale salvage operations were initiated to control the spread of the beetle
and recover economic value from infected timber before it burned or decayed. (Figures. 1 and 2).
By the time harvesting slowed down in the mid-1980’s, approximately 25% of the Bowron
watershed was logged, equivalent to 90,000 hectares (Wei and Davidson 1998). Harvest activity
was most extensive in the upper Bowron, removing 30% of the timber and producing a 50,000
hectare clearcut. Harvesting was also extensive in the middle and lower Bowron but occurred at
a slower rate. During peak harvest, approximately 700 loads of logs were removed from the
Bowron every day (Cozens 2004). Many riparian areas of small and mid-sized streams were
completely harvested.
To identify the potential impact of today’s mountain pine beetle infestation and large
scale salvage operations on streams and their riparian zones, present levels of ecologic function
in the Bowron River watershed more than 25 years after harvesting was determined using the
Routine Riparian Effectiveness Evaluation (RREE- FREP weblink). The RREE was used to
assess the current condition of streams and riparian areas in 35 basins within the Bowron River
watershed. Findings were then used to identify best management practices to protect stream and
riparian functions in mountain pine beetle infested areas.
1
Figure 1. North view toward the Bowron River from an unnamed hill in the Indian Point Creek watershed,
November 1984. (Photo courtesy of Robert Hodgkinson, MFR Prince George)
A Project
Funded
by:
2
Figure 2: A GIS projection of the Bowron River watershed. The view is up the Bowron River in a southern
direction toward the Bowron Lakes Park. High elevation areas are coloured dark green and they transition with
declining elevation to tan and then dark brown, the latter represents lowest elevations in the watershed. Salvage
harvested areas are identified by light green laying mostly along the valley bottoms.
Introduction
British Columbia is currently experiencing a mountain pine beetle epidemic that threatens to kill
eighty percent of the province’s commercial lodgepole pine by 2013 (MPB Program, Natural
Resources Canada, 2007). To recover the greatest economic value from the dead trees before
they burn or decay, the province has accelerated harvest in affected areas. Accelerated harvesting
has the potential to influence other forest values such as stream and riparian function, especially
when riparian timber is removed. The Forest and Range Practices Act currently allows for
harvesting in the riparian zone as an approved activity in a forest stewardship plan (FSP) or
under the Forest Planning and Practices Regulation (FPPR) s.51(f) for the purposes of sanitation
or s.51(g) to control damage by insects as long as it will not have a material adverse impact on
the riparian zone.
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The riparian zone is a sensitive ecotone that serves many functions such as erosion and runoff
control, protection of water quality, provision of shade and litterfall for aquatic biota, and habitat
for wildlife (Broadmeadow and Nisbet 2004). To gain some understanding of future conditions
of riparian zones and streams in MPB salvage areas, the Bowron Watershed was used as a
surrogate to identify the current condition of stream and riparian zones 20-30 years after large
scale salvage harvesting.
Purpose and Objectives
The Bowron Watershed study was initiated to identify the forest management activities that
place streams and their riparian areas at risk, as well as identify how they recover following
extensive salvage harvesting. The project identifies potential stream and riparian effects due to
accelerated harvesting practices that includes riparian zones and identifies best management
options to maintain stream and riparian function.
The principal objectives of this study were to:
1. Use the Routine Riparian Management Effectiveness Evaluation (RREE) to evaluate the
current condition of streams and riparian areas in the most intensively harvested subbasins of the Bowron River watershed that were identified during a 1994-1996 interior
watershed assessment process (IWAP).
2. Use both evaluations to assess stream and riparian recovery over time in the Bowron
River watershed.
3. Propose best management practices to protect stream and riparian functions in mountain
pine beetle infested areas.
The Bowron River Watershed
The Bowron River watershed is located fifty kilometers east of Prince George, British Columbia
(Figure 3). The watershed is approximately 3590 km2 in size with an elevation range of 6022447 m and is located within the Prince George and Quesnel Forest Districts. The Bowron River
emerges from the Bowron Lakes Provincial Park, where it flows north to the Fraser River. The
watershed comprises forty-three sub-basins that range in area from 11.26 km2 to 593.21 km2.
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The annual hydrograph is snowmelt dominated (Figure 4) but peak flows can occasionally occur
during fall months as a result of high-intensity rainstorms or rain on snow events (Beaudry and
Nassey 1994). The average annual peak flow (1977-2005) is 319 m3s-1 and the highest recorded
discharge on record (580 m3s-1) occurred in the spring of 1990.
The watershed is predominated by the Interior Plateau, specifically the Nechako Lowland, the
Quesnel Highland, and the West Cariboo Mountain physiographic regions. It is composed of
sedimentary and volcanic (igneous) rocks, with minor constituents of metamorphic and intrusive
rocks. Surficial geology consists of colluvial, fluvial, glacial-fluvial, and till deposits.
Significant ice presence during the Pleistocene has resulted in the deposition of thick deposits of
till, glacial-fluvial sands/gravels, and glacial lacustrine silts and clays which are currently being
incised. Brunisols, Podzols, and Luvisols are the most common soil orders within the watershed.
The watershed’s biogeoclimatic zone coverage is primarily of the Sub-Boreal Spruce (SBS) type
which occurs along most valley bottoms although there are some Interior Cedar-Hemlock valley
bottoms in the lower and middle sections of the watershed. Higher elevation areas include the
Englemann Spruce and Subalpine Fir (ESSF) zone as well as small areas of the Boreal Altai
Fescue Alpine (BAFA) and Interior Mountain-Heather Alpine (IMA) zones.
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Cities
Rivers
Highways
Peace Forest District
Bowron IWAP basins
District Boundaries
Central Cariboo Forest District
Headwaters Forest District
Peace Forest District
Prince George Forest District
Prince George Forest District
Quesnel Forest District
Prince George
Headwaters Forest District
Wells
Quesnel Forest District
Quesnel
Central Cariboo Forest District
0
5 10
20
30
Kilometers
40
Figure 3. General location of the Bowron River watershed in relation to the Prince George,
Headwaters, and Quesnel Forest District.
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250
Discharge (m3/s)
200
150
100
50
0
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Time (Month)
Figure 4. Average (1977-2005) daily discharge from the Water Survey of Canada station on the
Bowron River at Box Canyon (O8KDOO7). Largest flow volumes occur during the spring melt
between starts in late April and peaks in June.
Study Design
The Bowron River watershed was stratified using Level 1 Interior Watershed Assessment
Procedure (IWAP’s) (link to Guidebook) scores that were generated for each of the watershed’s
43 sub-basins between 1994 and 1996 (Figure 5). The RREE was used to assess current stream
and riparian condition at 2 sites in all of the high and moderate risk sub-basins, as well as eleven
low risk sites (not largely associated with roads or harvesting) (figure 5).
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7
6
5
8
2
3
1
2
3
4
5
6
7
8
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4
9
1
19
10
11
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17
43
12
16
13
14
A
C
D
E
F
G
H
Lower Bowron
Purden
Taspai
Swamp
Tsus/Fly
Unnamed A
Ames
42
41
15
40
39 38
20
35
36 37
21
34
22
30
23
24
33
31
32
25
29
26
15
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17
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25
26
27
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29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
Unnamed B
Spruce
Grizzly
Hah
Saw
Wendle
18 Mile
14 Mile
10 Mile
Towkuh
Ketchum
Summit
Antler
McKenna
Upper Bowron
Craze
Indian Point
Kruger
Littlefield
McKitrick
H3
Dominion
H4
Haggen
H2
H1
Post
Pinkerton
Middle Bowron
27
28
0
5 10 15 20
Kilometers
Figure 5. Location of the 43 sub-basins within the Bowron River watershed
(excluding residual areas that were identified in IWAP’s)
Field evaluations were conducted for an upper and lower stream reach in each selected subbasin. The lower site was selected to represent the cumulative effects of salvage harvesting on
the entire sub-basin and was generally a larger stream that may or may not have been harvested
at the sample reach. In contrast, the upper site, was a smaller stream that was selected to identify
localized harvesting effects and was typically harvested to the stream edge. A total of 70 stream
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reaches were assessed between May and October of 2007 including 59 treatment reaches and 11
control reaches (figure 6).
Sites
Rivers
Riparian Buffer Rank
High
Mod
Low
0
5
10
15
20
Kilometers
Figure 6. Riparian buffer risk themed risk map for each sub-basin using scores identified during
the 1994-1996 IWAP. The 70 RREE sample sites assessed during the 2007 study are identified
by white circles.
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Figure 6. Reference stream in the Swamp sub-basin (left photo) showing undercut banks, coniferous riparian
vegetation, coarse substrate and old stable LWD in the stream. A harvested stream section in the A sub-basin (right
photo) showing a lack of undercut banks, lack of coniferous in the riparian zone, fine sediments along the substrate,
and recently created LWD piles.
The Routine Riparian Effectiveness Evaluation
The RREE was developed in 2004 by the British Columbia Ministry of Forests to assess the
efficacy of current harvesting practices and policies in maintaining stream and riparian function
(weblink). The evaluation uses 15 indicators, each of which is assessed by several questions to
determine the level of riparian and stream function. The number of failed criteria determines the
level of ecological function, namely properly functioning (≤ 2 criteria failures); properly
functioning but at risk (3-4 criteria failures); properly functioning but at high risk (5-6 criteria
failures); and not functioning properly (> 6 criteria failures.). A properly functioning stream is
one where the stream and its riparian zone can withstand normal peak flood events without
experiencing accelerated soil loss, channel movement or bank movement, is capable of filtering
runoff, and can store and safely release water (Forest Practices Code, 1995). The riparian
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protocol expands on this FPC definition to include the ability of the riparian habitat to maintain
an adequate root network and large woody debris (LWD) supply, provide shade to limit changes
to the bank microclimate, and support adequate fish habitat.
The RREE requires the selection of a homogeneous sample reach which is identified as being at
least 30 channel widths long. As surveyors travel the sample reach they collect point and
continuous indicator information that address the 15 main questions in the RREE. These can be
subdivided into stream and riparian categories as follows:
Stream Indicators
Riparian Indicators
channel bed disturbance
large woody debris supply
channel morphology (figure 8)
disturbed or bare ground
aquatic connectivity
shade and bank microclimate
fish cover diversity
vegetations response
moss abundance (figure 8)
weeds
fine sediments
aquatic invertebrate diversity,
windthrow frequency
channel bank disturbance
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Figure 8. Counting LWD and measuring pool length (left photo) , calculating moss coverage on
streambed cobbles and boulders (right photo).
Results
RREE Assessment of Upper and Lower Basin Sites
The Bowron River watershed has not fully recovered from the large scale salvage harvesting
activities that took place between the 1970s to 1980s. The majority of the upper and lower
stream reaches were found to be either not properly functioning or functioning at high risk
compared to the reference sites which were functioning at low risk or properly functioning
(figure 9). The upper basin locations show a stronger response with 21 of 29 sites having lower
levels of function (i.e. not properly functioning or functioning at high risk) compared to 17 of 30
lower basin sites.
The difference in response between the upper and lower sub-basin locations can be primarily
attributed to failures of the riparian criteria. Upper basin sites generally had little no riparian
buffer and so most of the riparian questions received a “no” answer, downgrading the
classification from properly functioning. In contrast, lower basin sites had larger buffers and as a
result, fewer failures of the riparian indicators. Riparian zone silviculture efforts following the
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salvage harvesting program were unsuccessful in many areas because natural deciduous and
shrub growth were more successful at establishing than planted coniferous trees.
Upper sub-basin
Lower sub-basin
12
12
Harvested
Reference
10
8
8
6
6
4
4
2
2
0
0
o
cti
un
yf
erl
p
ro
tp
No
t
ta
hig
h
u
gb
in
ion
ct
n
Fu
g
nin
nc
Fu
k
ris
n
tio
ut
b
ing
a
sk
t ri
o
cti
un
yf
erl
g
nin
p
Pro
sk
ing
t ri
h
on
o
i
i
a
t
t
g
i
t
c
c
h
bu
fun
fun
at
ing
ut
rly
rly
n
b
e
e
o
p
ti
ing
rop
nc
Pro
on
tp
Fu
cti
No
n
Fu
g
nin
k
ris
Figure 9: Routine riparian effectiveness evaluation level of function scores for upper and lower
stream sample reaches in the Bowron River Watershed.
Comparison to IWAP Scores
The RREE scores follow a similar pattern to the IWAP scores (figure 10). Low-risk sites often
had higher RREE scores, indicating a higher level of function when compared to the moderate
and high risk sites. The upper basin low-risk group scored significantly higher than moderate
and high-risk groups (ANOVA P<0.05). There were no significant differences among the lowerbasin categories, and this may be due to the presence of a wider buffer that led to slightly higher
RREE scores. These findings indicate that there is some value to using the level 1 IWAP as a
riparian risk planning tool in forest management.
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Number of sites
Number of sites
10
Effectivenessss Evaluation
Score
Upper site
Lower site
4
3
(3)
(8)
(5)
(25)
(6)
2
(23)
1
0
Low
Moderate
High
Riparian Hazard Ranking
Figure 10. Interior watershed assessment (IWAP) riparian hazard rankings and the corresponding
Routine Riparian Effectiveness Evaluation (RREE) scores as identified by their position in the
sub-basin. Effectiveness evaluation scores range from 0 (not properly functioning) to 3 (properly
functioning) and error bars represent the 95% confidence intervals.
Other Findings
In addition to the information gathered specific to the RREE procedure, several other field based
observations are worthy of note for their potential to influence forest management activities,
including:

Fish passage barriers-hanging culverts were observed on S4 sized streams that dropped
1-2 meters downstream of main haul roads (figure 11). Similarly, fish passage would be
blocked by woody debris dams such as that observed at the mouth of Indian Point Creek
during the summer of 2007 (figure 11).
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Figure 11. A hanging culvert at Saw sub-basin (left photo) and the woody debris jam below the
bridge at the mouth of Indian Point Creek in August of 2007 (right photo).

Heavy equipment operation on roads, landing, and occasionally in the riparian zone was
found to compact and rut soil so that vegetation re-growth was limited decades after
salvage harvesting (Figure 12).
Figure 12. Machine tracks within the riparian zone of Unnamed A sub-basin, harvested over 20
years ago (left) photo) and a landing site that is over 20 years old in the Haggen Creek basin
above site 2 (right photo).
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
Riparian harvesting - salvaged riparian areas showed minimal conifer re-growth 20-30
years harvesting. Instead, these areas were dominated by deciduous re-growth (typically
alder and willow species), which may be inadequate for future LWD requirements. Even
where riparian zones were replanted, survival rates were low or growth was poor so
riparian stand structure was quite different to unlogged sites which typically included a
mixture of tree species (figure 13).
Figure 13. Riparian forests in a 30 (left photo) and 40 year stand (center photo) after harvesting
(Purden Site 1, Tsus/Fly Site 2) showing a significant deciduous canopy compared to the
reference site (right photo) showing more mixed species and conifer in particular (Swamp
basin).

Beaver activity in riparian zones and streams following salvage harvesting - in low
gradient systems can further decrease the level of watershed function and possibly
fisheries productivity by storing water, sediment, LWD, and possibly blocking fish
passage at old crossings that have not been decommissioned (figure 14).
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Figure 13. Beaver dams and a beaver lodge located in upper and middle Bowron (left and right
photo respectively). Both of these beaver dams use a road to block the flow of water.
Summary and Recommendations
In summary, the Routine Riparian Management Effectiveness Evaluation (RREE) inventory of
the Bowron River Watershed identified that there are significant resonant effects remaining from
the large scale salvage operations of the 1970s-1980s. Riparian harvesting in the upper sites led
to consistent failures of riparian indicators at these locations compared to the lower sites where
larger buffers were retained. Riparian retention is necessary to control erosion, protect water
quality, ensure long and short-term supply of LWD, moderate shade and water temperature, and
maintain the structural diversity and integrity of the riparian forest and stream habitat. In
keeping with these observations the following best management practices are recommended:

Maintain sufficient stand structure and volume in the riparian management zone to
protect the riparian reserve zone.

Minimize the use of heavy equipment in the riparian management zone of watersheds
with fine soil types to minimize soil disturbance.

Increase retention within the management zone for small and non-fish bearing streams
(S4-S6). In accordance with the Riparian Management Area Guidebook (link), retain and
buffer all trees within 10 m of the stream bank for S4 streams in low windthrow risk
areas. It should also be considered an option for S5 and S6 streams.

Retain understory and non-merchantable trees in the RMZ where harvesting activities
occur. Also retain all trees with root networks that extend into a streambank.
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
Avoid depositing debris into stream channels by maintaining adequate buffer width in the
riparian reserve and management zone. Where harvesting occurs near these zones fall
and yard away from streams. When slash and debris are inadvertently deposited, remove
only those stems that can be lifted clear without damage to the channel bed or bank. For
those that cannot be lifted clear, ensure the stem and limbs do not obstruct stream flow or
fish passage.

Brush and subsequently monitor replanted riparian zones to ensure planted trees are
growing efficiently.

Maintain natural drainage patterns. Natural drainage patterns must be considered and
incorporated into road network design

Ensure erosion and sediment control plans are developed and followed during road
construction in watersheds with sensitive soils.

Decommission road crossings once harvesting operations are completed and ensure site
rehabilitation is sufficient to prevent sediment delivery to the stream.

Remediate roads and landings, particularly those close to streams promptly after harvest
operations to prevent sediment delivery to the stream.
References
B.C. Ministry of Forests. 1995. Riparian Management Area Guidebook. Province of BC.
Victoria.
B.C. Ministry of Forests. 1995. Watershed Assessment Procedure Guidebook. 1st ed., Forest
Practices Branch, Min. Fore., Victoria, Available:
http://www.for.gov.bc.ca/tasb/legsregs/fpc/fpcguide/iwap/iwap-toc.htm
Beaudry, P. 1997. The Bowron River Watershed: A Case Study of a Cumulative Impact
Assessment. Prince George Forest Region. Forest Resources and Practices Team. Research Note.
Beaudry, P. and J. Nassey. 1994. Watershed Assessment Middle Reach Bowron River. Forest
Sciences. Prince George Forest Region. Internal publication. 36p.
Beaudry, P. and R. Delong. 1996. Upper Bowron River Watershed Assessment IWAP Level 1.
Analysis and Recommendations. Forest Resources Section. Prince George Forest Region.
Internal publication. 38p.
Berry, J. 2000. Channel Assessments of Selected Watersheds Within the Quesnel Forest District.
Submitted to West Fraser Mills Ltd. And Weldwood of Canada Ltd. and Ministry of Forests.
Internal Publication.
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Bowron Watershed Assessment Committee. 1997. Lower Bowron River Watershed IWAP Level
1. Analysis and Recommendations. Forest Resources Section. Prince George Forest Region.
Internal Publication.
Broadmeadow, S. and Nisbet, T.R. 2004. The effects of riparian forest management on the
freshwater environment: a literature review of best management practice. Hydrology and Earth
System Sciences, 8(3), 286-305.
Carmanah Research Ltd. Sherman, R. 1997. Upper Bowron River Watershed (Antler Creek and
Ketcham Creek Sub-basins) Fish Passage – Culvert Inspection (DRAFT). Submitted to Ministry
of Environment, Lands and Parks by Carmanah Research Ltd. Victoria, B.C.
Carmanah Research Ltd. 1998. Watershed Restoration Program, Watershed Level Riparian
Assessment of the Upper Bowron River Watershed. Submitted to West Fraser Mills Ltd. Quesnel
Division, by Carmanah Research Ltd. Victoria, B.C.
Carmanah Research Ltd. Harder, P. and T. Roy. 1998. Level 1 Fish Habitat Assessment
Procedure of the Upper Bowron River Watershed. Submitted to West Fraser Mills Ltd. Quesnel
Division, by Carmanah Research Ltd. Victoria, B.C.
Carmanah Research Ltd. Thorburn, G. and R. Pederson. 1998. Draft Report: Fish Habitat
Assessment Procedure Upper Bowron River Watershed. Submitted to West Fraser Mills Ltd.
Quesnel Division, by Carmanah Research Ltd. Victoria, B.C.
Cozens, R. 2004. The Upper Bowron Spruce Beetle Outbreak: A Case History. Internet
Reference.
http://www.forestry.ubc.ca/fetch21/Upper%20Bowron%20Spruce%20Beetle/ubsbo.htm
Environment Canada. 2007. National Climate Data and Information Archive. Internet.
http://climate.weatheroffice.ec.gc.ca/Welcome_e.html
Esker Construction Management Inc. 1994. Watershed Renewal Program, Bowron River
Watershed, Construction Report, October – November 1994. Ministry of Environment. Internal
Publication.
Esker Construction Management Inc. 1995. Watershed Renewal Program, Bowron River
Watershed, Level 1 Assessments, September 1994 – January 1995. Ministry of Environment.
Internal Publication.
Esker Construction Management Inc. 1995. Watershed Renewal Program, Bowron River
Watershed, Level 1 Assessments, May – July 1995. Ministry of Environment. Internal
Publication.
Esker Construction Management Inc. 1995. Watershed Renewal Program, Bowron River
Watershed, Level 1 Assessments, Appendix 1, May – July 1995. Ministry of Environment.
Internal Publication.
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Esker Construction Management Inc. 1995. Watershed Renewal Program, Bowron River
Watershed, Level II Assessments, September 1994 – January 1995. Ministry of Environment,
Lands and Parks. Internal Publication.
Firth Hollins Resource Science Corporation. 1994. Landslide Mapping upper Bowron
Watershed. Contract report to the Ministry of Environment Lands and Parks – Watershed
Restoration Programme.
Firth Hollins Resource Science Corporation. 1995. Bowron Watershed Programme, Sediment
Source Inventory Database. Contract report to the BC Ministry of Environment, Lands and
Parks. Internal Publication.
Forest Practices Code of British Columbia (FPC). 1995. Interior Watershed Assessment
Procedure Guidebook. Province of British Columbia.
Larkin, G.A., P.A. Slaney., P. Waburton and A.S. Wilson. 1998. Suspended Sediment and Fish
Habitat Sedimentation in Central Interior Watersheds of British Columbia. Province of British
Columbia, Ministry of Environment, Lands and Parks, and Ministry of Forests. Watershed
Restoration Management Report No. 7.
Ministry of Environment (MOE). 1986. The Soil Landscapes of British Columbia. Province of
British Columbia. Internal Publication.
Natural Resources Canada, Mountain Pine Beetle (MPB) Program. 2007. Online:
http://www.mpb.cfs.nrcan.gc.ca/index_e.html
Tripp, D.B., Tschaplinski, S.A. Bird and D.L. Hogan. 2007. Protocol for evaluating the
Condition of Streams and Riparian Management Areas (Routine Riparian Management
Effectiveness Evaluation). FRPA Resource Evaluation Program, B.C. Min. For. and B.C. Min.
Water, Land and Air Protection. Victoria, BC.
Wei, X. and G.W. Davidson. 1998. Impacts of large-scale timber harvesting on the hydrology of
the Bowron River Watershed. In mountains to sea: Human interaction with the hydrological
cycle. Canadian Water Resources Association 51st Annual Conference Proceedings, June 1998,
Victoria, BC. Pp. 45-52.
For more information
John Rex
Prince George Forest Region, 1011 – 4th Ave. Prince George, B.C.
Email: John.Rex@gov.bc.ca
David Maloney
Forest Practices Branch, 1011 – 4th Ave. Prince George, B.C.
Email: David.Maloney@gov.bc.ca
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