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Water Quality, Fish Tissue, and Bed Sediment Monitoring in Waterbodies of Fort Chaffee Maneuver Training Center, Arkansas, 2002-2004

By B.G. Justus and Gregory P. Stanton

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Abstract

The Fort Chaffee Maneuver Training Center is a facility used to train as many as 50,000 Arkansas National Guardsmen each year. Due to the nature of ongoing training and also to a poor understanding of environmental procedures that were practiced in the World War II era, areas within Fort Chaffee have the potential to be sources of a large number of contaminants. Because some streams flow on to Fort Chaffee, there is also the potential for sources that are off post to affect environmental conditions on post. This study evaluates constituent concentrations in water, fish tissue, and bed sediment collected from waterbodies on Fort Chaffee between September 2002 and July 2004. Constituent concentrations detected in the three media and measured at nine stream sites and four lake sites were compared to national and regional criteria when available. Two of the larger streams, Big and Vache Grasse Creeks, were sampled at multiple sites. All three sampled media were analyzed for insecticides, PCBs, explosives, and trace elements. Additionally, water samples were analyzed for nutrients and herbicides.

The different constituents detected in the three sample media (water, fish tissue, and bed sediment) indicate that land-use activities both on and off post are influencing environmental conditions. Contaminants such as explosives that were sometimes detected in water samples have an obvious relation to military training; however, the occurrence and locations of some nutrients, insecticides, and trace elements suggest that land use both on and off post also could be influencing environmental conditions to some degree.

Constituent concentrations at sites on Vache Grasse Creek, and particularly the most upstream site, which was located immediately downstream from an off-post wastewater-treatment facility, indicate that environmental conditions were being influenced by an off-post source. The most upstream site on Vache Grasse Creek had both the highest number of detections and the highest concentrations detected of all sites sampled. Event-mean storm concentrations and storm loads calculated from storm-flow samples at two sites each for Big and Vache Grasse Creeks indicate that storm loads were highest at the two Vache Grasse Creek sites for 24 of the 25 constituents detected. Further evaluation by normalizing storm loads at Big Creek to storm loads at Vache Grasse Creek by stream flow indicate that event loads at Vache Grasse Creek were about two or more times higher than those on Big Creek for 15 of the 25 constituents measured. Low concentrations of arsenic and lead were detected in water samples, but all detections for the two trace elements occurred in samples collected at the upstream site on Vache Grasse Creek. The nickel concentration in fish livers collected from the upstream site on Vache Grasse Creek was 45 percent higher than the median of a national study of 145 sites. Mercury concentrations in edible fish tissue, which are a widespread concern in the United States, exceeded an USEPA criterion for methylmercury of 300 g/kg in four of nine samples; however, concentrations are typical of mercury concentrations in fish tissues for the State of Arkansas.

Constituent concentrations at some sites indicate that environmental conditions are being influenced by on-post activities. Of the 55 (excluding total organic carbon) organic constituents analyzed in water samples, only 10 were detected above the minimum detection limit but four of those were explosives. Bed-sediment samples from one site located on Grayson Creek, and nearest the administrative and residential (cantonment) area, had detections for arsenic, copper, lead, manganese, nickel, and zinc that were above background concentrations, and concentrations for arsenic and nickel at this site exceeded lowest effect level criteria established by the U.S. Environmental Protection Agency. The site on Grayson Creek also had the only detections of DDT metabolites in bed sediment.

Concentrations of some trace elements in all media sampled for this study could also have a relation to on-post activities or conditions. Some trace elements detected may result from the combined effects of sedimentation (a possible consequence of soil erosion resulting from training activities and an extensive road system) and trace element concentrations in soils in western Arkansas. Regarding sedimentation (and soil erosion), turbidity data collected at the most downstream site on Vache Grasse Creek, and observations of substantial sediment deposition in both Vache Grasse and Big Creeks indicate that turbidity and associated sedimentation is a chronic problem that is impairing the ecological integrity of Fort Chaffee streams. Trace element concentrations at some sites may be related to this chronic sedimentation and the associated redox potential of the aquatic environments sampled.


TABLE OF CONTENTS

Figures
  1. Map showing Fort Chaffee boundaries and training ordnance-impact area and sampling sites
  2. Graph showing continuous stage, specific conductance, and turbidity data collected at Vache Grasse CreekSite 2, April 2004
Tables
  1. Sampling site information for sites at Fort Chaffee, Arkansas, 2002 through 2004
  2. Constituents analyzed in water samples collected at Fort Chaffee, Arkansas, 2002 through 2004
  3. Characteristics of fish collected for tissue (fillet and liver) analysis at Fort Chaffee, Arkansas, 2002
  4. Constituents analyzed in bed sediment and fish tissue samples collected from lakes and streams at Fort Chaffee, Arkansas, 2002
  5. Concentrations of organic compounds detected in water samples collected at Fort Chaffee, Arkansas, 2002 through 2004.
  6. Trace element concentrations for water samples collected at Fort Chaffee, Arkansas, 2002 through 2004
  7. Nutrient and other selected constituents detected in water samples collected at Fort Chaffee, Arkansas, 2002 through 2004
  8. Flow volumes and event mean concentrations for constituents detected above the laboratory minimum detectionlimit at four sites for the same storm event at Fort Chaffee, Arkansas, May 2003
  9. Computed storm loads for stream sites sampled at Fort Chaffee, Arkansas, May 2003
  10. A comparison of actual storm loads measured at Vache Grasse Creek Site 0 to flow-normalized storm loadsat Big Creek Site 4, May 2003
  11. Concentrations of organic compounds detected in fish fillets collected at Fort Chaffee, Arkansas, 2002
  12. Trace element concentrations in fish livers collected at Fort Chaffee, Arkansas, 2002
  13. Trace element concentrations in fish fillets collected at Fort Chaffee, Arkansas, 2002
  14. Organic compounds detected in bed-sediment samples at Fort Chaffee, Arkansas, 2002.
  15. Concentrations and associated toxicity values for trace elements analyzed in bed-sediment samples collectedat Fort Chaffee, Arkansas, 2002.



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