open pasture. The treatment basin was 1.42 mi2 with 2.8 total stream mi

and 2.0 mi of stream running through open pasture.

Land use in the study basins was about 80-90 percent agricultural

with the remaining predominantly developed (residential, industrial, or

commercial use) (fig. 1). The agricultural land in both basins was predominantly row crop (about 60 percent). Each basin had about 50-

55 acres of pasture land adjacent to stream channels.

Agricultural activity differed somewhat between basins from the preto post-treatment period. The average annual estimated amount of nitrogen (N) and phosphorus (P) applied in the treatment basin was 42,800

and 7,300 pounds per square mile (lb/mi2

), respectively. The average

annual estimated amount of N and P applied in the control basin was

64,200 and 12,600 lb/mi2

, respectively. The percentage decrease from

the pre- to post-treatment periods in the annual amount of N and P

applied in the treatment basin was 27 and 33 percent, respectively; the

control basin showed a 3-percent decrease in N and a 7-percent increase

in P over the same period. About 150 to 250 cows were pastured per

basin until 2000. The number of cows in both basins decreased by about

50 percent from 2000 to 2001.

How was Streambank Fencing

Studied?

The effects of streambank fencing

were documented for surface-water quality, benthic macroinvertebrates, and shallow ground-water quality. A nested experimental design was used to study

streambank-fencing effects on surface

water and benthic macroinvertebrates. The

primary design was a paired-basin

approach that required the use of two similar basins where one basin was a control

and the other had treatment applied. The

secondary approach for documenting surface-water changes included collecting

pre- and post-treatment data at sites within

the treatment basin upstream and downstream of fence installation. For shallow

ground water, a paired-well design was

used to determine if streambank fencing

affected the wells inside the fence as

opposed to the well outside the fenced

area. A detailed description of the study

design, methods, and results is presented

in Galeone and others (2006).

Data were collected from 1993 to

2001. Calibration data were collected

from October 1993 through mid-July

1997; fencing was installed from May

1997 through July 1997. All pasture areas

in the treatment basin along the stream

network were fenced with a buffer width

ranging from 5 to 12 feet (ft).

In cooperation with the Pennsylvania Department of Environmental Protection

Effects of Streambank Fencing of Near-Stream Pasture Land on a Small

Watershed in Lancaster County, Pennsylvania

by Daniel G. Galeone, Dennis J. Low, and Robin A. Brightbill

Why Study Streambank Fencing?

Streambank fencing to exclude animal access is a best-management

practice (BMP) targeted to reduce suspended-sediment and nutrient

inputs to streams. Exclusion of animals from the fenced area reduces

direct nutrient inputs to the stream, denudation of riparian vegetation,

and streambank trampling. A stream vegetative buffer also can reduce

the input of nutrients and sediment to the stream channel by filtration of

overland flow and through the retention of nutrients in the subsurface of

the riparian zone. The water-quality effects of specific BMP implementation on a basin scale are not well documented. The quantification of

specific BMP effects on water quality is critical to agencies or programs

concerned with protection of water resources.

Where was Streambank Fencing Studied?

Two basins within the predominantly carbonate Big Spring Run

Basin, a subbasin of Mill Creek Basin, Lancaster County (fig. 1) were

studied from 1993-2001. The control basin was 1.77 square miles (mi2)

with 2.7 total stream miles (mi) and 1.9 mi of stream running through

U.S. Department of the Interior

U.S. Geological Survey Printed on recycled paper

USGS Fact Sheet FS–2006-3112

September 2006

0

0

1 MILE

1 KILOMETER

39 59

76 15

T-1

T-2

T-4

C-1

T-3

T1-3

T2-3

C1-2

CONTROL BASIN

TREATMENT BASIN

STREAM

BASIN BOUNDARY

SURFACE-WATER-QUALITY SITE

SURFACE-WATER BENTHIC-MACROINVERTEBRATE SITE

AGRICULTURE

WATER

DEVELOPED

FORESTED

OTHER GRASS (LAWNS, PARKS, GOLF COURSES)

WETLAND

76 16

40 00

Pennsylvania

Study Area

SURFACE-WATER-QUALITY AND 

BENTHIC-MACROINVERTEBRATE SITE

Ground-water well nests are 

located at surface-water 

sites T-1 and T-2

Land-use data from 1993 (Lancaster 

County GIS Department)

EXPLANATION

FENCED STREAM 

Figure 1. Land-use map of study area and location of surface-water sites, ground-water well nests, and

fenced stream segments in the Big Spring Run Basin, Lancaster County, Pa.
For surface-water quality, low-flow and stormflow samples were collected at four continuous stream-gaging sites: T-1, C-1, T-2, and T-4

(fig. 1). Only low-flow samples were collected at T-3. Treated sites T-1

(at the outlet of the treatment basin) and T-2 (upstream site in the treatment basin that was a visually degraded pasture) were statistically compared to data collected from the outlet of the control basin (C-1) and to

untreated upstream sites in the treatment basin (T-3 and T-4). Surfacewater-quality samples were analyzed for total and dissolved forms of

nutrients and suspended sediment.

Benthic-macroinvertebrate samples were collected in May and September of each year at T-1 and C-1 (the basin-outlet sites), and T1-3,

T2-3, and C1-2 (upstream sites with C1-2 in the control basin). Benthicmacroinvertebrate statistical comparisons were conducted separately

between outlet and upstream sites because benthic-macroinvertebrate

communities showed similarities when comparing outlet to outlet and

upstream to upstream site. Habitat was qualitatively assessed during the

benthic-macroinvertebrate sampling.

Two nests of ground-water wells were installed in the treatment basin

to document effects of riparian vegetation on shallow near-stream

ground-water quality, one nest at the outlet of the treatment basin adjacent to T-1, and the other upstream adjacent to T-2 (fig. 1). At each well

nest, two shallow ground-water wells were near the stream channel

(treatment wells) and one shallow well was at a distance away from the

channel (control well) that was outside the fenced area. Well depths

ranged from 6 to 12 ft. Ground-water samples were analyzed for dissolved nutrients, fecal streptococcus, and field characteristics.

Changes from the pre- to post-treatment periods in constituents

during low flow and storm events for surface water and for shallow

ground water at treated sites were quantified using analysis of covariance (ANCOVA). The effects of fencing on the benthic-macroinvertebrate community were determined by comparing sites in the treatment

and control basins and using benthic-macroinvertebrate indices.

What were the Effects of Streambank Fencing

The primary factors affecting water quality from the pre- to posttreatment period were fence installation and changes in precipitation.

The most visually noticeable effect of streambank fencing was the establishment of a herbaceous riparian zone (fig. 2). Decreased precipitation

amounts during the post-treatment period caused stream discharge to be

56-63 percent less than the pre-treatment period. Changes in stream discharge were accounted for by ANCOVA so that the effects of fencing

could be quantified.

Did Streambank Fencing Affect Surface-Water Quality?

Low-flow data generally showed similar responses from the pre- to

post-treatment period for untreated and treated sites for nutrients and

suspended sediment (table 1); however, fencing effects were evident.

About 96 percent of the total-N concentration for all low-flow samples

was in the form of nitrate N. Low-flow periods contributed from 84 to

91 percent of the total-N yield at the continuous monitoring sites. From

the pre- to post-treatment period, all sites showed decreased yields of N

during low-flow periods

because of lower stream

discharge and lower concentrations. Yield reductions were greater at

treated sites (25-26 percent) than at the control/

upstream sites (11 percent) (table 1). On the

basis of ANCOVA analysis, relative reductions

from the pre- to posttreatment period in lowflow yields of total N and

nitrate N were 17 percent

for T-1; conversely, relative increases in lowflow yields of total N and

nitrate N were 9 to

11 percent for T-2. P concentrations for low-flow

samples showed significant increases of 0.03 and

0.54 mg/L from the preto post-treatment period

at T-1 and T-2, respectively. Most of this

increase was caused by

increased concentrations of dissolved P; the likely source was an agricultural field immediately upgradient from T-2. The low-flow yield of total

P showed average relative percent increases during the post-treatment

period at T-1 and T-2 of 51 and 220 percent, respectively; however, only

3-10 percent of the total-P yield for these sites occurred during low-flow

periods. Suspended-sediment concentrations for low-flow samples

decreased at all sites from the pre- to post-treatment period (table 1);

however, low flow only contributed about 5-10 percent of the suspended-sediment yield.

Stormflow data showed significant reductions in suspended-sediment concentrations and yields from the pre- to post-treatment period;

N and P yields showed varied results. Larger percentage decreases in

suspended-sediment concentrations were seen at treated sites (56-69 percent) rather than untreated sites (40-54 percent) (table 2). The average

percentage relative reductions in the suspended-sediment yield from the

pre- to post-treatment period at treated sites was 36 and 46 percent,

respectively. Changes in N and P yields for stormflow samples differed

by site. The average reduction in stormflow yield of total N for T-1 was

19 percent during the post-treatment period; the average relative

increase in yield of total N for T-2 was 28 percent. Similarly, the average

reduction in stormflow yield of total P for T-1 was 22 percent during the

post-treatment period, and the average relative increase in yield of total

P for T-2 was 46 percent.

Pre-treatment photo, May 1996

Post-treatment photo, May 1998

Figure 2. Tributary site (T-2) in treatment basin in the Big Spring Run Basin,

Lancaster County, Pa., before (top) and

after (bottom) fence installation.

Table 1. Mean concentrations (in milligrams per liter) and estimated daily yields (in pounds per day per square mile) for low-flow samples collected

during the pre- and post-treatment periods at the five surface-water sites.

Constituent

C-1 T-1 T-2 T-3 T-4

Pre Post Pre Post Pre Post Pre Post Pre Post

Total-nitrogen concentration 10.6 9.47 11.7 8.61 11.4 8.60 12.0 11.4 12.7 10.1

Total-nitrogen yield 69.0 45.2 53.5 29.9 41.2 29.9 77.2 47.2 34.4 26.0

Total-phosphorus concentration .05 .06 .06 .09 .09 .63 .03 .05 .04 .04

Total-phosphorus yield .339 .312 .238 .350 .259 1.14 .228 .246 .156 .122

Suspended-sediment concentration 42 24 28 13 46 37 21 16 21 11

Suspended-sediment yield 286 107 134 41.1 154 93.1 139 69.9 73.6 33.5

Number of samples 95 108 96 107 92 82 92 107 59 71
Table 2. Mean concentrations (in milligrams per liter) and yields (in pounds per square mile) for stormflow samples collected during the pre- and

post-treatment periods at the four continuous surface-water sites.

C-1 T-1 T-2 T-4

Constituent

Pre Post Pre Post Pre Post Pre Post

Total-nitrogen concentration 5.55 5.76 7.25 7.09 5.19 5.34 3.93 4.11

Total-nitrogen yield 153 103 143 87.2 138 126 119 88.7

Total-phosphorus concentration .76 .99 .97 1.00 .71 .86 .46 .51

Total-phosphorus yield 35.1 29.2 32.2 22.4 34.8 34.0 24.1 20.5

Suspended-sediment concentration 608 457 708 313 673 263 344 219

Suspended-sediment yield 29,100 12,500 27,000 9,630 30,500 15,700 16,400 10,800

Number of samples 71 89 71 83 62 101 30 86

Changes in yields at the treatment basin outlet, T-1, relative to control/upstream sites showed a reduction during the post-treatment period

for all constituents except dissolved P. The overall yield reductions at

T-1 were 37 percent for suspended sediment, 19 percent for total N, and

14 percent for total P (table 3). These results indicate that 2 mi of stream

fencing with cattle exclusion in a small (1.42 mi2 drainage) basin can

significantly reduce nutrient and suspended-sediment loads to the stream

system.

Table 3. Overall water-quality changes in constituent yields for the

treated sites relative to control/upstream sites for the post-treatment

period based on analysis of covariance (ANCOVA) results.

T-1 T-2

Constituent (percent (percent

change) change)

Total nitrogen -19 +21

Dissolved nitrate -18 +15

Dissolved ammonia -36 +10

Dissolved phosphorus +19 +94

Total phosphorus -14 +51

Suspended sediment -37 -44

In contrast, all constituent yields for T-2 (0.36 mi2 drainage) relative

to control/upstream sites increased during the post-treatment period

except for suspended sediment. The overall post-treatment changes at

T-2 showed a 44 percent decrease in suspended-sediment yield while

total-N and total-P yields increased by 21 and 51 percent, respectively.

The dissolved-P yield was the largest increase (94 percent) of all constituents listed. These increases were not only due to an upgradient field

contributing dissolved P through subsurface pathways, but also to cattle

excreting waste at the cattle crossings. Water samples collected in the

stream channel upgradient of the T-2 stream gage indicated that concentrations of dissolved ammonia and organic N and dissolved P were

higher downstream relative to upstream of the crossings.

Did Streambank Fencing Affect Benthic Macroinvertebrates?

The qualitative assessment of habitat during benthic-macroinvertebrate sampling indicated habitat improved after fence installation. The

most noticeable effects on habitat characteristics were for the primary

and tertiary categories (see Plafkin and others, 1989, for a detailed

description of parameters) (table 4). Of the tertiary characteristics,

streamside-cover scores were least affected by fence installation, primarily because only herbaceous vegetation was established inside the

fenced area, and streamside-cover scores increase as tree cover

increases. The secondary category of habitat variables appeared to be

least affected by fence installation; nevertheless, these variables showed

some improvements. These variables are affected by flow regime, and it

may be that the lower stream discharge during the post-treatment period

reduced any changes that might have taken place.

Table 4. Post-treatment changes in habitat characteristics at the outlet

and upstream sites in the treatment basin relative to control sites.

[Change less than one score unit was defined as NC (no change)]

Habitat characteristic Outlet/Upstream

Bottom substrate available cover +/+

Primary

Embeddedness +/NC

Velocity to depth ratio NC/+

Channel alteration -/+

Bottom scouring and deposition +/-

Secondary

Pool/riffle, run/bend ratio +/+

Bank stability +/NC

Tertiary

Bank vegetative stability +/+

Streamside cover NC/+

Total habitat score +/+

The fence installation allowed vegetation to establish itself along the

streambanks, which helped to trap sediment in overland runoff prior to

reaching the stream channel. The habitat along the banks and within the

stream improved, allowing for less sedimentation of the stream bottom

and more niches for benthic macroinvertebrates. When looking at the

overall numbers for total habitat (table 4), the results were positive and

the habitat improved at the outlet and at upstream sites in the treatment

basin.

Selected benthic-macroinvertebrate indices are presented in table 5.

Taxa richness, EPT (Ephemeroptera, Plecoptera, and Trichoptera)

index, and percent oligochaetes improved during the post-treatment

period at the outlet and upstream sites in the treatment basin relative to

control sites (table 5). The relative number of taxa showed a larger

increase at the upstream sites than outlet sites. The EPT index and percent oligochaetes showed more improvement at the outlet than the

upstream sites (relative to control sites). An increase in taxa richness was

likely related to habitat improvement. Positive changes in the EPT index

and a decrease in the percent oligochaetes usually are correlated with

improving water quality.

Other benthic-macroinvertebrate metrics showed contradictory

responses during the post-treatment period. The HBI (Hilsenhoff biotic

index) scores showed improvement at T-1 compared to C-1 meaning that

more pollution-sensitive benthic macroinvertebrates inhabited T-1; conversely, the upstream sites showed degradation in HBI scores during the

post-treatment period. The percent dominant taxa decreased at T-1 relative to C-1 and increased at upstream sites (T1-3 and T2-3) relative to

C1-2 during the post-treatment period. A decline in this percentage indicates more evenness and a healthier community.

Did Streambank Fencing Affect Shallow Ground-Water Quality?

Differences in shallow ground-water flow paths were at least partly

responsible for the large differences in chemistry and physical character-
Table 5. Post-treatment changes in benthic-macroinvertebrate

indices at the outlet and upstream sites in the treatment basin

relative to control sites.

[+ indicates improvement in conditions based on that index]

Index Outlet/Upstream

Taxa richness +/+

Hilsenhoff biotic +/-

EPT +/+

Percent dominant taxa +/-

Percent oligochaetes +/+

istics between the two well pairs. Dissolved-nitrate concentrations at the

T-2 well nest were about one order of magnitude higher than for the T-1

well nest (table 6). Low dissolved-nitrate concentrations at the T-1 well

nest were partially attributable to denitrification. Other differences

between shallow wells at T-1 and T-2 were evident for dissolved ammonia and P, but in this case, concentrations were higher for the T-1 well

nest. One similarity between the well nests was the relative decrease in

water temperature during the post-treatment period.

ANCOVA results from the paired-well comparisons indicated fence

installation significantly affected shallow ground-water quality. The

concentrations of dissolved ammonia, dissolved nitrate plus nitrite, and

fecal-streptococcus counts decreased in the two shallow wells at site

T-2 but increased in the shallow wells at site T-1 relative to control wells

during the post-treatment period (table 6). The one constituent that

showed relative increases at the T-2 well nest and not at T-1 during the

post-treatment period was dissolved P. It appeared the source of the P

was an upgradient field where animal manure had historically been

applied. The likely reason for the opposite post-treatment responses

(except dissolved P) was the difference in shallow ground-water flow

paths. At the T-2 well nest, the shallow ground water moved from outside the fence to the stream (gaining stream), while the opposite was true

at T-1, where the stream was actually losing water to the shallow groundwater system; thus, at T-1, any impacts of vegetative establishment

inside the fence on water quality were not impacting the shallow wells

inside the fence, but moving away from them. The reductions apparent

for the shallow wells at the T-2 well nest would be somewhat expected

given that the cows were not allowed to access the area near these wells

after fence installation.

Table 6. Mean values for shallow ground-water samples collected during the pre- and post-treatment periods at the two well nests in the treatment

basin and percentage change for treatment wells relative to control wells during the post-treatment period based on analysis of covariance for shallow

well pairs.

[mg/L, milligrams per liter; col/100 mL, colonies per 100 milliliters; positive percent change indicates the treatment wells increased relative to the control well during the

post-treatment period]

T-1 well pairs T-2 well pairs

Constituent Treatment Control Percent

change

Treatment Control Percent

Pre Post Pre Post Pre Post Pre Post change

Temperature, degrees Celsius 12.0 11.9 11.9 12.5 -5.7 11.8 11.8 11.7 12.5 -4.1

Dissolved nitrate plus nitrite, mg/L 1.13 .62 1.67 1.40 15 13.9 15.4 14.9 16.6 -2.3

Dissolved ammonia, mg/L .40 .46 .31 .24 38 .082 .016 .035 .036 -51

Dissolved phosphorus, mg/L .08 .19 .01 .01 -7.8 .01 .01 .01 .04 33

Fecal streptococcus, col/100 mL 1,270 1,900 200 43 5.8 694 2,360 858 4,620 -56

Range in number of samples 20-43 12-44 20-43 15-44 18-42 12-41 20-43 15-44

Conclusions

This study indicated that a small buffer width along a stream in pasture land can have a positive influence on surface-water quality, benthic

macroinvertebrates, and near-stream shallow ground-water quality.

Overland runoff processes that move suspended sediment to the stream

were controlled (or reduced) to some extent by the vegetative buffer

established

Results indicated streambank fencing resulted in decreases in N-species, total-P, and suspended-sediment concentrations and yields at the

outlet of the treatment basin relative to untreated sites; however, dissolved-P concentrations and yields increased. These results indicate that

nutrient management, in conjunction with streambank fencing, is important in helping to control nutrient loadings to streams in this agricultural

setting.

An upstream site (T-2) in the treatment basin showed post-treatment

reductions in suspended-sediment yields and increases in N and P yields.

The different results for these treated sites indicates the effects of streambank fencing should be studied at as large a scale as possible because

field-scale influences on water quality as drainage area decreases can

mute the effects of fencing.

Benthic-macroinvertebrate data indicated streambank fencing had a

positive influence on benthic macroinvertebrates and their habitat. More

improvement was detected at the outlet of the treatment basin than the

upstream sites. Probably the most important biological metric, taxa richness, indicated a greater number of benthic-macroinvertebrate taxa at

treated relative to control sites after fencing.

Results indicated fencing improved shallow ground-water quality

(for the well nest in a stream-gaining area), as noted by decreased concentrations of N species and fecal-streptococcus counts. This improvement only occurred at the well nest where the stream was gaining water

from the shallow ground-water system.

References Cited

Galeone, D.G., Brightbill, R.A., Low, D.J., and O’Brien, D.L., 2006, Effects of

streambank fencing of pasture land on benthic macroinvertebrates and the

quality of surface water and shallow ground water in the Big Spring Run Basin

of Mill Creek Watershed, Lancaster County, Pennsylvania, 1993-2001: U.S.

Geological Survey Scientific Investigations Report 2006-5141, 183 p.

Plafkin, J.L., Barbour, M.T., Porter, K.D., Gross, S.K., and Hughes, R.M., 1989,

Rapid bioassessment protocols for use in streams and rivers — Benthic macroinvertebrates and fish: Washington, D.C., U.S. Environmental Protection

Agency, Office of Water Regulations and Standards, EPA 440-4-89-001,

196 p.

This project was a cooperative effort between the USGS and the PaDEP.

PaDEP funding was through the National Monitoring Program (NMP) of the

U.S. Environmental Protection Agency. The NMP was developed to document

the effects of nonpoint-source pollution-control measures and associated

land-use modifications on water quality.

For more information on USGS activities in Pennsylvania, visit the

Pennsylvania District web site at http://pa.water.usgs.gov/.