EFFECTIVENESS OF BEST MANAGEMENT PRACTICES TO PROTECT

WATER QUALITY IN THE SOUTH CAROLINA PIEDMONT’

Thomas M. Williams, Donal D. Hook, Donald J. Lipscomb, Xiaoyan Zeng,

and Joseph W. Aibistor?

Abstract-The South Carolina Forestry Commission published the most recent edition of Forestry Best Management

Practices (BMP) in 1994. The Commission has been doing compliance monitoring since 1990 and has generally found

compliance near 90 percent. In 1995 we installed a study to measure effectiveness of these BMP’s on four experimental

watersheds on the Clemson Experimental Forest, in the Piedmont of South Carolina. After 15 months of pre-treatment

monitoring three watersheds were cut and site prepared using all appropriate BMP’s. Following logging, site preparation

treatments were: natural regeneration; shear, rake and pile; and herbicide and burn. Suspended sediment, nitrate,

phosphate, pH, and water temperature were measured throughout the pre treatment period and for 12 months post

treatment. Suspended sediments were ten fold less than logging without BMP’s and near to those measured due to

increased flow due to tree removal. All other parameters were similar to pre-treatment levels.

INTRODUCTION

The Southeastern States have depended on voluntary Best

Management Practices for water quality protection in

application of forestry practice. The program in South

Carolina has been typical. The first publication of silvicultural

guidelines by the South Carolina Forestry Association

occurred in 1976. These were updated in 1969 to include

practices on forested wetlands (SCFC 1989). Both

publications were revised and included into a single booklet

of Best Management Practices in 1994 (SCFC 1994).

In order to protect water quality, voluntary BMP’s must be

effective and implemented. South Carolina has had a

program to examine compliance with the published BMP’s

since 1990. Compliance has been very high and increasing

slightly, from 84.9 percent in 1990 to 89.5 percent in 1994

(Hook and others 1991, Adams and Hook 1994, Adams

1994). These surveys initially focused on roads and

harvesting, but with the 1994 manual site preparation was

included. A survey of site preparation sites in 1996 showed

86.4 percent compliance with site preparation BMP’s

(Adams 1997). Through a vigorous educational program for

landowners, loggers, and professional foresters the South

Carolina Forestry Commission has achieved compliance

with voluntary guidelines similar to that of mandatory

statutes used in other regions.

South Carolina BMP’s are primarily based on research

conducted during the 1960’s and 70’s (Dickerson, 1975,

Beasley 1979, Hewlett and Douglass 1964, Hewlett 1979,

Ursic 1975). The main findings were that forest practices

were most likely to impair water quality with suspended

sediment (Yoho 1980). The most common cause of

sediment movement were road building and operation of

heavy equipment in or near stream channels. A major

portion of the BMP manual is devoted to road building

practices and to streamside protection.

Streamside protection is afforded by a 40 foot (12.2 m)

primary zone on each side of the stream channel, or an 80

foot (24.4 m) zone on trout streams where side slopes

exceed 5 percent. On perennial streams individual stems

can be removed as long as a minimum 50 sq ft/ac (11.5

m2/ha) of overstory trees are left. Soil disturbance is to be

minimized and mechanical site preparation and planting are

prohibited, as are landings, portable sawmills, or the using

toxic liquids, including oil and gasoline. On intermittent

streams the primary SMZ can be clearcut as long as the

channel is protected and all other practices are used. A

secondary SMZ is also required on streams where side

slopes are greater then 5 percent. On slopes from 5 to 20

percent the secondary SMZ is to be 40 feet (12.2 m), 80 feet

(24.4 m) on slopes of 21 to 40 percent, and 120 (36.6 m)

feet on slopes greater then 40 percent. In this zone,

clearcutting and mechanical operations are permitted but

soil disturbance is limited to less than 15 percent of the

surface. Decks roads, and handling or storing toxic materials

are also to be avoided.

The study reported here was a test of the South Carolina

Forestry BMP’s applied in the Piedmont. Since it is

characterized by relatively steep slopes, erodible soils, and

a history of severe erosion, the Piedmont was considered to

be the most critical physiographic province. Hewlett (1979)

found that forested Piedmont watersheds in Georgia

naturally lost 80 kglhalyr and that logging without BMP’s

resulted in a loss of 7500 kg/ha for each of the first two

years after logging. Van Lear and others (1985)

characterized very small (~3 ha) watersheds in the South

Carolina Piedmont and found natural suspended

concentrations of 35 mg/l which increased to 72 mg/l

following careful logging. Sediment yields were 30 kg/ha/yr

under natural conditions and 151 kg/ha the first year after

logging. Since logging was done without roads or landings in

the watershed and skidding was done with small tractors

that minimized soil disturbance, these values can be

considered to be due to increased channel scour that is an

unavoidable consequence of increased flow associated with

forest removal.

METHODS

Four watersheds were chosen in the Seneca River ’ watershed on the Clemson Experimental Forest

approximately five km northeast of Seneca, SC. The four

’ Paper presented at the Tenth Biennial Southern Silvicultural Research Conference, Shreveport, LA, February 16-18, 1999.

’ Professor, Baruch Forest Science Institute, P.O. Box 596, Georgetown, SC 29440; Professor Emeritus, Research Demonstration Forester, Ph.D.

Candidate, and MS Candidate, Department of Forest Resources, Clemson University, Clemson, SC 29634, respectively.

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watersheds varied in size from 37 to 67 hectares and were 3700 automatic water sampler. Each flume was calibrated in

primarily Madison and Pacolet soils (table 1.) and were the field by timed volumetric measurements to assure flow

significantly steeper than those used by Hewlett (1979) and rate errors of less than three percent. Flow was measured

Van Lear and others(l985) Vegetation was similar on all continuously from February 1996 to June 1998. Flow rates

four watersheds with upland oak-hickory stands with mixture were averaged hourly and data was transferred to Hewlett

of loblolly pine (Pinus taeda L.) and shortleaf pine (Pinus Packard model 540 palmtop computers and later to Excel

echinata Mill.). Coves included yellow poplar (Lirodendron spreadsheets where calibration regressions were applied.

fulipifera L.) with oak and hickory. Ramsey Bridge, Water quality parameters were determined on one stormflow

Kenamore One and Kenamore Two also had loblolly pine sampling and two baseflow samples each month. Stormflow

plantations. samples were taken by the ISCO automated samplers.

Logging treatments were applied to three watersheds to test

three common types of site preparation practiced in the

South Carolina Piedmont. All areas and site preparation

plans were based on silvicultural prescription and resulted in

the portions of each watershed treated as listed in table 1.

The Holley Springs watershed hardwood stand was clearcut

and regenerated by stump sprouts. A 13.8 ha pine plantation

on the Ramsey Bridge watershed was clearcut and

regenerated by an herbicide and burn treatment. Following

logging of the pine, all non-merchantable hardwoods were

treated with Velpar and burned with the slash. On the

Kenamore Two watershed a 5.3 ha pine plantation was

thinned, and 10.9 ha of hardwood was clearcut. Five

hectares of this clearcut was then site prepared by shearing

all non-merchantable material and root raking all slash and

non-merchantable stems into windrows.

Samplers were triggered when the flow recorders detected a

stage rise greater than a predetermined amount. Since base

flow varied between seasons and watersheds the triggering

stage rise varied also, usually between two and ten

millimeters. One-liter samples were collected each hour for

the first 12 hours, then a 250 ml sample was collected each

hour with four samples aggregated into a single bottle.

Samples were collected for 60 hours. Also two, one-liter

samples were taken during baseflow by manual triggering of

the automated samplers.

Each watershed was instrumented with a two foot (60.9 cm)

H flume, with an ISCO Model 4230 flow recorder and Model

Samples were preserved with sulfuric acid. Samples were

first filtered with .45 pm pre-weighed filters. For most

samples the entire liter was filtered through a single filter

although 100 ml aliquots were used for samples with high

sediment concentration. Filters were then dried to 100 C and

re-weighed to the nearest 0.1 mg. Aliquots of filtrate were

then analyzed for NO,-N by cadmium,reduction, PO,-P by

stannous chloride, and Ca, K and Mg by atomic adsorption

Table l-Characteristics of experimental watersheds, soils, slopes, and treatments

Watershed Size Madison Pacolet Saluda Starr Worsham

---------------------------Hectare-----------------------

Holley Springs 67.0 33.6 28.7 1.1

Ramsey Bridge 58.4 37.4 16.0 4.8

Kenamore One 45.9 17.2 23.8 2.9 .5

Kenamore Two 36.8 2 7 4.2 8.3 1.0

Slopes

o-5 5-20 20-40 >40

Portion

Treatment treated

_ _ _ _ _ _ _ _ _ _ _ _ _ percent _ _ _ _ _ _ _ _ _ _ _ _ _ _ - - Percent - -

Holley Springs 12.3 26.7 46.5 9.3

Ramsey Bridge 16.8 12.4 53.8 17.0

Kenamore One 9.4 17.1 55.1 18.4

Kenamore Two 10.2 9.7 47.7 32.4

Logged 2 2

Herbicide 22.5

Control 0

Mechanical 29.9

and thin 14.4

MADISON SERIES: Clayey, kaolinitic, thermic Typic Kanhapludults. The Madison series consists of well drained,

moderately permeable soils that formed in residuum weathered from felsic and intermediate, micaceous high grade

metamorphic rock. PACOLET SERIES: Clayey, kaolinitic, thermic Typic Kanhapludults. The Pacolet series consists of very

deep, well drained, moderately permeable soils that formed in material weathered mostly from acid crystalline rocks of the

Piedmont uplands. Slopes commonly are 15 to 25 percent but range from 2 to 80 percent. SALUDA SERIES: Loamy,

mixed, mesic, shallow Typic Hapludults. The Saluda series consists of shallow, well drained, moderately permeable soils

that formed in weathered granite, gneiss, or schist. Slopes range from 8 to 90 percent. STARR SERIES: Fine-loamy,

mixed, thermic Fluventic Dystrochrepts. The Starr series consists of deep, well drained, moderately permeable, loamy

soils that formed in Piedmont alluvium. Slopes range from 0 to 8 percent. WORSHAM SERIES: Clayey, mixed, thermic

Typic Ochraquults. Soils of the Worsham series are deep and poorly drained. They formed in local alluvium at the heads

of drainage ways in the Piedmont uplands.

272
spectrophotometry (Greenberg and others 1992). Water

quality sampling began in April of 1996 and continued until

June 1998.

Sediment and elemental loss were estimated using flow

records and a flow volume to nutrient concentration relation

determined from the storm flow sampling in that particular

month. For each month, the flow rates and elemental

concentrations were used to determine 60 hourly estimates

of elemental loss. A regression was then calculated between

flow rate and elemental loss. That regression was then used

on the hourly flow rates for that element and that month to

produce elemental loss estimates for each hour during the

month. Separate regression equations were used for each

element and each month on each watershed. Regression

estimates were used for all hourly flow rates where the

regression estimate exceeded the product of the flow rate

and the average base flow concentration. In no case was a

regression equation used to estimate elemental loss for flow

rates below the lowest rate measured during the 60 hour

stormflow sample. In general the regression equation

predicted elemental loss similar to the base flow

concentration at the end of the 60 hour stormflow sampling

period.

Statistical analysis was conducted as paired watersheds

with each of the three treated watersheds compared to the

control in separate analyses. For sediment and each

element a monthly export amount and flow weighted mean

concentration were calculated. A paired T-test was used to

compare differences between each watershed values and

the control during the pre-treatment period to those obtained

during the post-treatment period. Since the post-treatment

period occurred during the El Nino weather pattern posttreatment values in each watershed were also compared to

pre-treatment with a simple two tailed T - test.

RESULTS

Instrument installation was completed in March 1996 and

data collection began in April 1996. Logging was begun in

June 1997 and completed by July, site preparation treatment

were applied in August-September 1997 and post-treatment

measurements continued until June 1998. For analysis April

1996 to June 1997 was considered pre-treatment and July

1997 until June 1998 was considered post-treatment. During

the fifteen month pre-treatment period 153 cm of rain fell

while 166 cm fell during the post-treatment year (fig. 1).

Holley Springs and Kenamore Two watersheds produced

more runoff and Holley Springs and Ramsey Bridge

produced slightly less sediment but for most other elements

the watersheds were similar (table 2). Pre-treatment

regressions were made based on hourly flows from each

watershed. Kenamore One was intermediate in most values

and well correlated to the other three watersheds and

became the control. Hourly flows were best predicted by the

equations

Holly Springs flow = 0.921 Kenamore One flow + 0.414

+ = 0.74 (1)

Ramsey Bridge flow = 0.872 Kenamore One flow + 0.198

?= 0.88 (2)

Kenamore Two flow = 0.970 Kenamore One flow + 0.006

rz = 0.91 (3)

These equations were used to predict post-treatment flows

of the three treated watersheds. The post-treatment period

Figure l-Rainfall and runoff from four experimental watersheds

from April 1996 through June 1996.

contained substantially higher rainfall due to the El Nino

weather pattern. The combination of this weather pattern

and the extent of treatment on the steepest watershed, posttreatment flows in the Kenamore Two watershed were

substantially increased (table 3).

DISCUSSION AND CONCLUSION

There are a number of clear results of this experimental

application of logging and site preparation using Best

Management Practices. Increased rainfall during the posttreatment period had a number of impacts. Concentrations

of suspended sediment, phosphate and all cations were

increased in all watersheds, many of these increases were

also highly significant. Channel erosion is generally found

when streams must accommodate larger peak flows.

Suspended sediment increased in all streams, with

concentrations increases relatively proportional in all

watersheds. Nitrate concentrations declined in three of the

watersheds with higher rainfall, which may be due to wetter

soils. Soluble phosphate concentrations were correlated to

both flow rate and suspended sediment concentration.

As one might expect, cutting of portions of these watersheds

resulted in significantly higher rates of runoff. Cutting the

largest portion of the steepest watershed resulted in the

greatest increase in runoff. The two watersheds with site

preparation also showed significant small increases in

nitrate concentration. The increases were greater on the

watershed with the greatest proportion of vegetation

disturbance. Total losses of sediment and cations were also

significantly increased on the two site-prepared watersheds.

This was due to increased runoff since neither watershed

showed significant concentration increases.

However, the point of this study was not to define small

differences between the site preparation options but to

determine how well BMP’s protected water quality. This can

best be determined by examining these results in relation to

the prior research on Piedmont logging. Hewlett presented

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Table 2-Pre-treatment total flows, per year flows, flow weighted concentrations, and estimated

annual material exports from the four experimental watersheds

Watershed

Mean

flow Sediment N03-N PO4-P Ca K Mg

m3m msd ms/! PM w-d w/l m@

Hoiley Springs 0.810 44.0 0.109 11 0.89 0.91 1.18

Ramsey Bridge 574 39.2 .089 1 3 1.36 .82 1.06

Kenamore One .426 71.5 .068 12 1.78 .92 1.10

Kenamore Two .411 66.1 .044 1 2 1.53 .91 1.16

Holiey Springs

Ramsey Bridge

Kenamore One

Kenamore Two

Flow Sediment N03-N PO4-P Ca K Mg

Cm/yr -----------------------Kg/ha/yr-----------------------

58.6 249 .61 .061 5.11 5.58 5.70

46.9 184 .31 .059 5.62 4.09 5.00

46.5 332 .30 .053 5.88 4.29 5.12

52.8 377 .32 .084 7.97 5.21 8.64

Table 3-Post-treatment total flow, flow weighted nutrient concentrations, and estimated annual material

exports from the four treated watersheds

Watershed

Holiey Springs

Ramsey Bridge

Kenamore One

Kenamore Two

Mean

flow Sediment N03-N PO4-P Ca K Wi

m3m m9/1 mSn I@ ms/! mSn mg/l

0.907 97.8 0.081 2976 1.37” 0.93 0.97b

.800 95.1 .087' 1 .7ga 1.15d 1.43"

.422 114 .034 20 2.04a 1.17d 1.34

.631 89.6 .143" 1 7 l-83= 1 .23a 1.25

Flow Sediment N03-N PO4-P Ca K WI

cm/yr

Holiey Springs 70.9b 894 58 .067 9.74d 6.64 6.88

Ramsey Bridge 67.7b 647 .60 .182d 1 2.2bd 7.80bd 9.73ba

Kenamore One 45.8 522 .I6 .091 9.35d 5.35 6.14

Kenamore Two 90.2b 802 .81b .095 1 0.32bs 6.99" 7.03ba

a Post-treatment significantly different from pre-treatment, a = .Ol.

b Difference due to treatment significant a = .Ol.

’ Difference due to treatment significant a = .05.

d Post-treatment significantly different from pre-treatment, a = .05.

results of logging without BMP’s while Van Lear and others

presented unavoidable changes in water quality associated

with tree removal. Figures 2 present results of this study in

relation to those two studies.

very small watersheds near tributary heads that only

produced runoff for short periods after rain. The larger

watersheds used by Hewlett and this study capture

subsurface flow and result in larger flows during both pretreatment and post-treatment. One might expect higher

Runoff results (fig. 2a) are similar to Hewlett for the runoff amounts in this study since the watersheds were

mechanical site preparation treatment. Van Lear measured considerably steeper than those used by either other study.

274
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Figure 2-A comparison of this study compared to previous studies of logging impacts in the Piedmont: (a) Runoff, (b) Nitrate nitrogen,

(c) Soluble Phosphate, (d) Calcium, (e) Potassium, and (9 Magnesium.

275
Nitrate nitrogen (fig. 2b) shows increases for the two site

preparation treatments. Neither other study found an

increase in nitrate nitrogen. Soluble phosphorus (fig. 2c)

also increased on the site preparation treatments in contrast

to Van Lear’s data. Hewlett did not measure soluble

phosphorus. Calcium (fig. 2d), Potassium (fig. 2e), and

Magnesium (fig. 2f) show results very similar to Van Lear but

considerably less than Hewlett for both pm-treatment and

post-treatment. It seems that Hewlett’s experiment was done

on soils that were derived from more basic bedrock or that

were not as severely weathered or eroded.

Sediment concentration (fig. 3) shows the most important

aspect of this study. All of the other measures in Figure 2

show that all three studies behaved relatively similarly and

resulted in high quality water. Forested Piedmont

watersheds have relatively high average sediment

concentrations (30-70 mg/l) compared to other

physiographic regions. Severe erosion from previous land

use has resulted in streams which are actively eroding

channel banks. In this experiment sediment concentrations

were higher on the steepest watersheds.

Cutting trees increase the rate of stream flow and result in

increased channel erosion. Van Lear’s careful experiment

found an increase from 40 to 70 mg/l due to this increased

flow Logging with BMP’s increases these values to roughly

100 mgll. This value is roughly ten fold less than occurred

with logging prior use of BMP’s. Increased storm activity

associated with the El Nino weather pattern also resulted in

concentrations of 100 mgll. Sediment yield did increase

more substantially with logging and site preparation since

flow increased considerably. Yields from very careful logging

on upper slopes resulted in yields of 150 kglhalyr while the

most severe treatment in this study yielded 800 kglhalyr (fig.

3). Although the change in yield is more pronounced than in

concentration it is still ten fold below that produced prior to

BMP’s.

This study applied South Carolina’s latest BMP’s on the

most difficult physiographic province in the state. The test

was done with commercial loggers using normal silvicultural

practice subject only to careful adherence to the BMP’s. The

experiment placed the most severe treatment on the

smallest steepest watershed in the experiment. The results

of this severe test were sediment concentrations and yields

ten fold below those found when BMP’s were not used.

ACKNOWLEDGMENTS

We would like to thank Louwanda Jolley, Carrie

Cuthbertson, and Jeffery Vernon for laboratory analysis and

Joseph Gable for aid in constructing field installations. This

study was funded in part by an EPA 319 grant to Donal D.

Hook.

REFERENCES

Adams, T.O. 1994. Implementation monitoring of forestry best

management practices on harvested sites in South Carolina.

Columbia, SC: South Carolina Forestry Commission.

Adams, T.O. 1998. Implementation monitoring of forestry best

management practices for site preparation in South Carolina.

Southern Journal of Applied Forestry. 22: 74-80.

Adams, T.O.; Hook, D.D. 1994. Compliance with silvicultural best

management practices on harvested sites in South Carolina.

Southern Journal of Applied Forestry. 18: 183-187.

Beasley, R.S. 1979. Intensive site preparation and sediment loss on

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America Journal. 43: 3.

Dickerson, B.P. 1975. Stormflows and erosion after tree length

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methods for examination of water and wastewater. Washington,

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practices for South Carolina’s forest wetlands. Columbia, SC:

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South Carolina Forestry Commlsslon. 1994. South Carolina’s best

management practices in forestry. Columbia, SC: South Carolina

Forestry Commission. 81 p.

Urslc, S.J. 1975. Harvesting southern forests: a threat to water

quality? In: Non-point sources of water pollution. Blacksburg, VA:

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1985. Sediment and nutrient export in runoff from burned and

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Journal of Environmental Quality. 14: 189-174.

Yoho, N.S. 1980. Forest management and sediment production in

the South-a review. Southern Journal of Applied Forestry. 27: 36.

Figure &Sediment yields for this study in comparison to two others

in the Piedmont.

276