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Effects of Hardened Low-Water Crossings on Periphyton and Water Quality in Selected Streams at the Fort Polk Military Reservation, Louisiana, 1998-99 and 2003-04

Scientific Investigations Report 2007-5279

Prepared in cooperation with the U.S. Army Joint Readiness Training Center and Fort Polk
By:
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Abstract

In 2003, the U.S. Geological Survey (USGS), at the request of the U.S. Army Joint Readiness Training Center and Fort Polk, began a follow-up study to determine whether installation and modification of hardened low-water crossings had short-term (less than 1 year) or long-term (greater than 1 year) effects on periphyton or water quality in five streams at the Fort Polk Military Reservation, Louisiana. Periphyton data were statistically analyzed for possible differences between samples collected at upstream and downstream sites and before and after low-water crossings were modified on three streams, Big Brushy Creek, Tributary to East Fork of Sixmile Creek, and Tributary to Birds Creek, during 2003?04. Periphyton data also were analyzed for possible differences between samples collected at upstream and downstream sites on two streams, Tributary to Big Brushy Creek and Little Brushy Creek, during 1998?99 and 2003. Variations in periphyton communities could not be conclusively attributed to the modifications. Most of the significant changes in percent frequency of occurrence and average cell density of the 10 most frequently occurring periphyton taxa were increases at downstream sites after the hardened low-water crossing installations or modifications. However, these changes in the periphyton community are not necessarily deleterious to the community structure. Water-quality data collected from upstream and downstream sites on the five streams during 2003?04 were analyzed for possible differences caused by the hardened crossings. Generally, average water-quality values and concentrations were similar at upstream and downstream sites. When average water-quality values or concentrations changed significantly, they almost always changed significantly at both the upstream and downstream sites. It is probable that observed variations in water quality at both upstream and downstream sites are related to differences in rainfall and streamflow during the sample collection periods rather than an effect of the hardened low-water crossing installations or modifications, but additional study is needed.

Geospatial Extents

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Effects of Hardened Low-Water Crossings on Periphyton and Water Quality in Selected Streams at the Fort Polk Military Reservation, Louisiana, 1998-99 and 2003-04
Series title:
Scientific Investigations Report
Series number:
2007-5279
Edition:
Version 1.0
Year Published:
2007
Language:
ENGLISH
Publisher:
Geological Survey (U.S.)
Contributing office(s):
Louisiana Water Science Center
Description:
vi, 36 p.