The Effects of Forest Management on Sediment, Turbidity, and Salmonid Population Health
Maryanne Reiter, Hydrologist, Weyerhaeuser Co.Doug Martin, Fisheries Scientist, Martin Environmental
Western Forestry Conservation AssociationSeptember 8, 2016. Heathman Lodge, Vancouver WA.
Focus of This Talk
• Why do we care about sediment and turbidity?
• Landscape context of sediment• Sediment and forest practices• Management effectiveness/trends• Biological effects
Image from : Ministry of Forestry, Canada
Why is turbidity a concern? It is an important water quality parameter that can affect photosynthesis and sight–feeding organisms.
Images from: http://pubs.usgs.gov/fs/2004/3069/
Why is sediment a concern? High sediment can decrease the survival of salmonid eggs by reducing water flow through the streambed gravel. Excessive sediment can also affect fish habitat by reducing pool volume.
Sediment and Turbidity
Landscape Control on Sediment Yield
Suspended Sediment Varies Across the Landscape
2016 USGS Sediment Load Model for Western Oregon.
It examined sediment data from 68 stations and predicted sediment using several landscape variables including lithology, rainfall, wildfires, land cover, etc.
(Wise and O’Connor, 2016)
Suspended Sediment Varies Across the Landscape
“The significant explanatory variables were lithologic province, precipitation, and area disturbed by recent wildfire”
(Wise and O’Connor, 2016)
Effects of Forest Management on Sediment
Past Practices Had Pronounced Effect on Sediment
First Alsea Harvest
(Beschta, 1978)
Forest practice rules have changed through time to address sediment delivery to streams
“..increases were caused primarily by mass soil erosion from roads.”1
97
8
“Road segments where vegetation was cleared from the cutslope and ditch produced about 7 times as much sediment …”1
99
9Forest Road Studies and Practice Changes
“Research and monitoring show that wet weather road use can influence water quality, especially turbidity.”
Oregon Department of Forestry
20
03
Creating sidecast 1964 Pulling it back 1990s
Road Practices Have Evolved to Address Sediment
Road Design, Construction and Maintenance
ROAD CONSTRUCTION•Cut and fill slopes − minimize heights•Durable surfacing − depth and quality of aggregate•Cross drains sufficient to minimize direct delivery•Manage around stream crossings; e.g., sediment traps,
concrete approaches to bridges •Disconnect roads from streams
ROAD MAINTENANCE/USE •Periodic assessments,
storm patrols•Keep vegetation in
ditches; avoid grading when too wet
ROAD DESIGN and PLANNING •Scheduling road construction during appropriate weather and soil moisture
conditions•Constructing roads away from landslide-prone areas
Photo courtesy of Kelly James
1996: 57% of roads connected to stream network (Wemple et al., 1996).
Disconnecting Roads from Streams
2009: 73% of roads surveyed had low delivery potential. Of the high delivery potential roads, ½ were disconnected and only 12% were connected (Martin, 2009).
Photo by Kelly James
But There Are Still Issues
In 2015 NOAA and EPA found Oregon’s forest practice rules deficient in addressing water quality from legacy roads (roads built and abandoned before FPA (1971). But the state is concerned that accessing true legacy roads could lead to far greater impacts than allowing passive recovery.
Photo from Kelly James
Legacy Roads
Other Practices That Have Helped Reduce Sediment
• Stream buffers
• Yarding systems (suspension)
• Discontinuing broadcast burning
• Limits on clearcut size and adjacent harvest timing
NBL
NB6
NB7
Alsea Watershed after 2009 harvest
0
50
100
150
200
250
300
350
400
450
Needle Branch Deer Creek H.J. Andrews 1 Caspar Creek Hinkle
Historic
Contemporary
Have These Changes Made a Difference?%
Inc.
Su
spen
ded
Sed
imen
t C
om
par
ed t
o E
xpec
ted
Se
dim
ent
Load
Slide from G. Ice
Though Sediment Not Completely Eliminated
Rate of recent timber harvest “equivalence” explained the greatest amount of variability in turbidity. Drainage area was also significant but was a secondary variable.
(Klein et al., 2012)
Contemporary Studies of Sediment and Forest Practices: What Are We Learning?
Deschutes
Alsea
Hinkle
Trask
Mica Creek
Mica Creek Experimental Watershed
Started in 1989 in north Idaho. 6,700 acre watershed on Potlach Corp. ownership.Elevation: 3200 – 5240 ftVegetation: 70-80 yr old mixed conifer. Treatments are clearcuts and partial cuts.
Paired and nested watershed study
Slide modified from Terry Cundy, 2015
Clearcut harvesting produced a significantly higher suspended load immediately following the harvest. But within one year following harvest, it was gone. No increase in partial harvest. Karwan et al., 2007
Mica Creek Sediment Load: Local
Road construction and upgrades did not produce a significant difference in monthly suspended sediment load compared to the control.
Flume 5 Load (metic ton / sq. km)
Flu
me
4 L
oa
d (
me
tic t
on
/ s
q.
km
)
9080706050403020100
90
80
70
60
50
40
30
20
10
0
treatment
3: Recovery Post-Road
4: Immediate Post-Harvest
5: Recovery Post-Harvest
1: Pre-Treatment / Calibration
2: Immediate Post-Road
Downstream Cumulative Suspended Load
Mica Creek Suspended Load: Downstream
No increase in sediment load downstream of harvest
Slide modified from Terry Cundy, 2015
Goal: Quantify effects of contemporary forest practices on the physical, chemical and biological characteristics of streams
Approach: Cooperative, multi-disciplinary and long-term. Each watershed study has a slightly different in focus.
Oregon Watersheds Research Cooperative
2014 harvest
Trask Road Sediment Study
5 sampling locations
Field method: automatic samplers at road crossings before, during upgrade and during harvest and haul
Arismendi et al., in review
Before Road Harvest
background C = 0.2
C =1
C = 3
C = 5
Example
Dif
fere
nce
in
tu
rbid
ity
(N
TU
)
New road
Sediment/Turbidity Data Analysis: Statistical vs Biological Significance
YesNo
e.g.
Data analysis method:
Is the median of [below – above] ≤ a
certain threshold?
Why does this analysis method matter? Because statistical significance ≠ biological significance.
• Observed minimal increases in sediment & turbidity
• Local disturbances important in headwaters
• Natural variability within/between streams
Trask Road Sediment Study Results
pre-harvest
post-harvest
Susp
en
de
d s
ed
ime
nts
(m
g/L
)
n.s.
Control sites: decrease or no significant changes in suspended sediment after harvest; treated sites increase after harvest
Wilcoxson Signed Ranks test, alpha=0.05
Other Trask Sediment Results: Small Streams
Slide from Alba Argerich et al., 2015 (AFS)
Control and treated sites: no significant changes in biomass after harvest
Mann-Whitney test, alpha=0.05
Can a Change in Sediment Change Fish Food?While a change in sediment was indicated, it was not detected in the macroinvertebrate biomass
Slide from Alba Argerich et al., 2015 (AFS)
Hinkle Creek Sediment Response: Large Stream
Slide modified from Skaugset 2013
Hinkle Creek Sediment Response (cont.)
• Sediment yield much lower than previous literature.
• The results appear to be more muted, with increases in the 20% to 40% range.
• These results are in agreement with and correlate with the increases in water yield.
Slide modified from Skaugset 2013
In 1975, Weyerhaeuser installed 4 permanent monitoring stations. Suspended sediment, turbidity, streamflow, air and water temperature was measured at the four stations.
Deschutes River, WA Long-Term Study
Medium Stream
2 Small Streams
Large Stream
Deschutes Study Location
Deschutes Management Through Time
0
1
2
3
4
5
6
7
1975 1980 1985 1990 1995 2000 2005
Pe
rce
nt
bas
in h
arve
ste
d, r
oad
co
nst
ruct
ed
an
d r
e-
con
stru
cte
d
Percent of road network constructed Percent of basin harvested % reconstructed
Turbidity and Flow Trends Through Time
0
2
4
6
8
10
12
14
1974 1979 1984 1989 1994 1999 2004 2009
Me
dia
n w
inte
r fl
ow
(cm
s) a
nd
tu
rbid
ity
(NTU
)
Deschutes Median Winter Turbidity and Flow
Median Winter Turbidity Median winter flow
We saw a decline in median winter flow adjusted turbidity even as we continued to harvest and construct roads.
Flow Weighted Turbidity and Management
-4
-3
-2
-1
0
1
2
3
20
30
40
50
60
70
80
90
100
1974 1979 1984 1989 1994 1999 2004 2009
Med
ian
Win
ter
Flo
w W
t Tu
rb (
NTU
)
% B
asin
Har
vest
ed o
r R
oad
Net
wo
rk C
on
st.
Year
Median Winter Flow Wt Turbidity and Cumulative % Basin Harvested or Roaded
Cumulative % of road network
Cumulative % of basin harvested
Median winter flow-adjusted turbidity (NTU)
Forestry Effects in a Landscape Context
Forestry Effects in a Landscape Context
0
2
4
6
8
10
12
14
1. DR
M
2. Mitc
hell C
r
3. Huckle
berry C
r
4. Johnson C
r
5. Thurs
ton C
r low
er
6. Litt
le D
eschute
s
7. Desc
h bl L
inco
ln
8. Lew
is C
r
9. Desc
hutes 3
350 B
r
10. B
uck Cr
11. W
estfork
Cr
12. W
are C
r
13. H
ard C
r
14. U
pper Des
chutes
Med
ian
win
ter
turb
idit
y (
NT
U)
1981 median winter turbidity (NTU) 1997 median winter turbidity (NTU)
Continental glaciation Resistant volcanic mountain slopes
Sediment Summary
• Early practices had a pronounced effect on sediment• There have been many changes in forest practices through
time to address sediment delivery• The changes have minimized, though not eliminated sediment
delivery to streams• The question is whether the amount of sediment generated
and delivered to stream channels is impacting the biota
Arismendi I, Groom JD, Reiter M, Johnson SL, Dent L, Meleason M, Argerich A, Skaugset AE (in review) Suspended sediment and turbidity after road construction/improvement and forest harvest in streams of the Trask Watershed Study, Oregon. Forest Ecology and Management
Beschta, R.L., 1978. Long-term patterns of sediment production following road construction and logging in the Oregon Coast Range. Water Resources Research, 14(6), pp.1011-1016.
Karwan, D.L., Gravelle, J.A. and Hubbart, J.A., 2007. Effects of timber harvest on suspended sediment loads in Mica Creek, Idaho. Forest Science,53(2), pp.181-188.
Klein, R.D., Lewis, J. and Buffleben, M.S., 2012. Logging and turbidity in the coastal watersheds of northern California. Geomorphology, 139, pp.136-144.
Reiter, M., Heffner, J.T., Beech, S., Turner, T. and Bilby, R.E., 2009. Temporal and spatial turbidiy patterns over 30 years in a managed forest of western Washington . Journal of the American Water Resources Association, 45(3), p.793.
Wemple, B.C., Jones, J.A. and Grant, G.E., 1996. Channel network extension by logging roads in two basins, Western Cascades, Oregon1.
Wise, D.R., and O’Connor, J.E., 2016, A spatially explicit suspended-sediment load model for western Oregon: U.S. Geological Survey Scientific Investigations Report 2016–5079, 25 p., http://dx.doi.org/10.3133/sir20165079.
Literature Cited
