### 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.

271watersheds 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.

272spectrophotometry (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

273Table 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 capturesubsurface 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.

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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.

275Nitrate 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 steep watersheds in the gulf Coastal Plain. Soil Science Society of America Journal. 43: 3.

Dickerson, B.P. 1975. Stormflows and erosion after tree length skidding on Coastal Plain soils. Transactions of American Society of Agricultural Economics. 18: 887-888,872.

Greenberg, A.E.; Clesceri, L.S.; Eaton, AD. 1992. Standard methods for examination of water and wastewater. Washington, DC: American Public Health Association.

Hewlett, J.D. 1979. Forest water quality: an experiment in harvesting and regenerating Piedmont forests. Athens, GA: University of Georgia, School of Forest Resources. 22 p.

Hewlett, J.D.; Douglass, J.E. 1988. Blending forest uses. Res. Pap. SE-37. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southeastern Forest Experiment Station. 15 p.

Hook, D.D. [and others]. 1991. A survey of voluntary compliance of forestry best management practices in South Carolina. Columbia, SC: South Carolina Forestry Commission. 23 p.

South Carolina Forestry Commission. 1989. Best management practices for South Carolina’s forest wetlands. Columbia, SC: South Carolina Forestry Commission. 20 p.

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: Virginia Polytechnic Institute and State University: 145-151.

Van Lear, D.H.; Douglass, J.E.; Cox, S.K.; Augspurger, WK. 1985. Sediment and nutrient export in runoff from burned and harvested pine watersheds in the South Carolina Piedmont. 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.

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