HYDRO20750

• Permit No: C1980007
• IBM Index Class Name: Hydrology
• Doc Date: 7/5/2005
• Doc Name: Evaluating the Effectiveness of Postfire Rehabilitation Treatments
• From: MCC
• To: DMG
• Permit Index Doc Type: Correspondence
• Media Type: D
• Archive: No

monitoring were done on a given fue. This may be a
result of the incompleteness of our rewrd, or it could
reflect the fact that National Foreate could afford to do
one or the other kind of monitoring, but not both. The
interests of the personnel charged with monitoring
may also have determined the type ofmonitoring that
was done.
Because BAER treatments are generally designed
to reduce erosion, sedimentation, and flooding, the
moat valuable assessments of treatment effectiveness
would be those that actually quantify sediment move-
ment and water yield. Relatively few reports mea-
suredsediment movement, and virtually none tried to
quantify water yield. Methods used for measuring
sediment movement ranged from erosion bridges,
which measure change in the distance to ground
surface from a Fixed suspended bar, to height of ero-
sionpedestals ]eft after sediment movement occurred,
to sediment traps such as troughs and silt fences
installed below hillsides or in small awalea. Erosion
bridge results generally proved difficult to evaluate,
because sediment was as likely to be deposited on a
spot (eroded from above) as removed. Pedestal mea-
surement was considered to overstate erosion, be-
cause it is measured only in places where sediment
lose has obviously occurred and cannot easily be gen-
eralized to a larger area. Traps and silt fences pro-
vided the most informative results, although their
tendency to overtop made many measurements mini-
mumestimates rather than actual quantities. In addi-
tion, it is difficult to determine the size of the area
actually contributing to a trap or fence. If fixed area
plots above a trap are used, the plot boundaries may
affect sediment movement. Moat reports using these
methods did not tell how contributing area was de-
termined for the "tons per acre" sediment output
calculation.
Because monitoring results can become the basis for
future management decisions, it is critical that moni-
toring efforts and reports be as scientifically credible
as possible. Whether defending a decision to seed or
explaining why a flood occurred despite BAER treat-
ments, Forests need to be able to support their work
with good data from their own and other Foreate'
monitoring efforts. There is little published research
on most BAER treatments. With the limitations of
monitoring reports mentioned above, we did not feel
that we could evaluate the validity ofmost reports, let
alone generalize the results of monitoring done on one
Forest to another area. There is a critical needfor more
and better monitoringofBAER treatments (discussed
further in the Recommendations section).
Moat monitoring focused on the moat expensive
(stream channel treatments, contour-felled logs), wide•
spread(seeding), orcontroveraial(aeeding)treatment
applied after a fire. The results from these efforts are
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-63. 2000
incorporated into our discussions of specific treatment
effectiveness.
Treatment Effectiveness
The basis for the BAER program is whether treat
ments effectively ameliorate poetfire emergency con-
ditions without compromising ecosystem recovery.
For many treatment methods, effectiveness could only
be determined qualitatively. From our interviews and
the monitoringreporta, it became apparent that treat-
ment success often depended on appropriate imple-
mentation (see appendix B) and cooperative poatfire
weather. Quantitative dataon effectiveness were avail-
able for relatively few treatments. We were able to
analyze hillelope treatments in more detail than chan-
nel or road treatments.
Hillslope Treatments-Increasing infiltration of
rain water and preventing soil from leaving the hillslope
are considered the most effective methods to slow
runoff, reduce flood peaks, retain site productivity,
and reduce downstream sedimentation. Mulching and
geotextiles were rated the most effective hillslope
treatments by our interviewees, because they provide
immediate ground cover to reduce raindrop impact
and hold soil in place. Poatfire research and monitor-
ing reports showed dramatic decreases in eediment
movement where mulch was applied (Bautista and
others 1996, Faust 1998). However, both methods are
relatively costly and are difficult or impossible to
install in remote locations (appendix B}. Mulch is most
useful near roads or in critical areas at the tope of
elopes. Geotextiles are generally applied to small ar-
eas, such as road cuts and fills. Aerial seeding and
contour-felled logs are the two moat common hillalope
treatments. Their effectiveness in reducing erosion
had mixed reviews from the published literature,
monitoringreports,andinterviewreaulta,eventhough
the Forest Service spent over $25 million in the last
three decades on each treatment.
Little contour•fellingwas implementedin the 1970'x,
and only $4 million was spent in the 1980'x. Since
then, however, contour-felled loge have gained in
popularity as ahillslope treatment. Moat interviewees
thought the effectiveness was good or excellent. Moni-
toring studies did not evaluate runoff, infiltration, or
sediment movement changes due to the contour-felled
loge; they only reported sediment storage. Monitor-
ing studies indicated that contour-felling could be
about 60 percent efficient (DeGraff 1982) and could
reduce downslope sedimentation by about 40 to 60 per-
cent (Griffith 1989a). Maximum trapped sediment of
6.7 yds ac 1 (13 ms ha 1) or about 6.8 t ac 1(17 Mg ha-')
by contour-felled loge was reported by Miles and
others (1989). McCammon and Hughes (1980), on the
other hand, estimated storage at about 72 yds ac 1
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