Bacteriological Water Quality of Forested and Pastured Streams Receiving Land-applied Poultry Litter

Poultry production is a growing industry in East Texas, generating about 360,000 m tons of broiler litter each year as a by-product for application on pasturelands. Grab samples of fecal coliform (FC) and fecal streptococcus (FS) were collected monthly between March and December 1996 and FC and E-coli samples were collected weekly between July and October 2001 at six sites on the Waffelo and Terrapin Creeks in Nacogdoches County, Texas to assess possible impacts of poultry litter application on bacterial water quality. Sites were grouped by three pairs with each pair consisting of one upstream site in predominantly forested area and one downstream site in a pastured area receiving land application of poultry litter. All pastured watersheds had a 10 to 150 m buffer of riparian forest and/or unfertilized pasture between the stream and areas on which broiler litter was applied. FC concentrations exceeded the 200 cfu/100 ml contact recreation standards in more than 50% of observations, regardless of forested or pastured conditions. E-coli samples did not violate standards and has been shown to be a better indicator of fecal contamination. Current broiler litter land-application rates on pasturelands did not cause significantly higher FC concentrations than natural wildlife activities on forested watersheds. Water pH was the only parameter significantly correlated (r \u3e 0.50) with FC in the study areas. No significant correlations were detected between FC and other aquatic parameters including stream discharge, temperature, salinity, specific conductance, and dissolved oxygen. The study suggests that background variation in bacteriological parameters may mask land-use practices, though a longer period of observations with greater sampling frequency at more study sites may reduce observed variation in the present study

Clearcutting and shearing on a saline soil in East Texas: Impacts on soil physical properties

Soil samples, or in-situ measurements, were collected at seven occasions and at six depths to study the Impact of three forest conditions on soil physical properties of a saline soil in E. Texas. Soil bulk density, CW. of silt plus clay at the surface horizons, soil water content, soil water retention, and depth to groundwater Increased following intensive site preparation. Differences in these properties between the commercial clearcuttlng and undisturbed forest were small. The wet soil conditions created in the Intensive preparation site are not likely to be responsible for the failure of artificial pine regeneration. In areas where site preparation may cause standing water on the surface, all plants and stumps should be left intact after marketable timber is removed

Forest Clearcutting and Site-Preparation on a Saline Soil in East Texas: Impacts on Water Quality

Three 0.02 hectare plot-watersheds were installed on a saline soil in the Davy Crockett National Forest near Apple Springs, Texas. Each plot was installed with an H-flume, FW-1 automatic water level recorder, Coshocton N-1 runoff sampler, and two storage tanks. One watershed was undisturbed forested and served a control, one was clearcut without any site-preparation, and the third was clearcut, V-blade sheared, windrowed, and vegetation regrowth was prevented for the first 2 years. A total of 274 storms were recorded during the four-year study period, 1989-1992. Average annual sediment losses for the study period were 55, 197, and 1,530 kilograms per hectare per year for the control, commercial clearcut, and sheared plots, respectively. These losses are about average for most studies conducted in East Texas and the Southeast and are well below average losses for all land uses in the Southeast. Sediment losses and surface runoff were significantly greater from the sheared plot-watershed than from the control and the commercial clearcut plots. Employing Wischmeier and Smith’s (1978) long-term average Rvalue for the USLE overestimated annual sediment yield for the study period, while two shortcut models developed in the United States resulted in more accurate predictions and are good substitutes for the long-term R-value. Total losses in surface runoff of PO4, NO3, NO2, TKN, K, Ca, Mg, Na, Al, Fe, Zn, and Cu were higher on the site-prepared plot watershed than the other two. Losses of PO4, TKN, and NO2 were higher on the commercial clearcut plot than the control. Losses were not high enough to adversely affect forest productivity. Concentrations of elements were generally below established USEPA surface water quality standards and were not high enough to adversely affect plant growth

Mercury Concentrations in Streams of East Texas

Recent studies on potential mercury (Hg) contamination of fish from East Texas lakes and waterways have caused concern about mercury levels in East Texas waters. Historical records of Hg concentrations in 33 East Texas streams showed that median concentrations for each stream segment were no different than other U.S. streams. All the means and medians for stream segments having at least 20 recorded measurements were less than Texas (2.4 µg/L) water quality standards. Water samples collected in December 1995 and March 1996 from 6 different stream sites in Nacogdoches County had concentrations similar to historical records. Due to biological magnification, fish Hg levels can be 20,000 times greater than water Hg levels and levels are greater in large fish than in small fish. Although a recent study on sediment cores in 13 East Texas reservoirs and lakes suggested possible increases in mercury concentrations across the region, all Hg concentrations in water and sediment were far below Texas acute and chronic quality standards. No significant correlations were found between fish mercury concentrations and mercury concentrations in water or sediment. Potential agricultural inputs of Hg in East Texas are very low; the most likely source of Hg is atmospheric deposition from fossil fuel combustion and other industrial practices. The following may be considered to minimize potential health risks: 1) consume smaller fish from a variety of waterbodies, 2) increase consumption interval, 3) avoid eating skin and fatty tissues, and 4) limit consumption to quantities recommended by the Texas Health Department

Runoff of Silvicultural Herbicides Applied Using Best Management Practices

Nine small (2.2 to 2.9 ha) and four large (70 to 135 ha) watersheds in East Texas, USA, were instrumented to compare herbicide runoff under different silvicultural systems with best management practices (BMPs). Two treatments were evaluated: conventional, with clearcutting, aerial herbicide site preparation, and hand-applied banded herbaceous release; and intensive, in which subsoiling, aerial fertilization, and a second-year aerial herbicide application were added. Herbicides were applied as operational tank mixes. The highest imazapyr concentration found in stream water was 39 mg L‑1 during the first storm after application (23 days after treatment, DAT) and in-stream concentrations during runoff events dropped to L‑1 in all streams by 150 DAT. The highest hexazinone concentration was 8 mg L‑1 for the banded application and 35 mg L‑1 for the broadcast application the following year and fell to L‑1 in all streams by 140 DAT. The highest sulfometuron methyl concentration found during a runoff event was 4 mg L‑1 and fell to L‑1 in all streams by 80 DAT. About 1 to 2% of applied imazapyr and less than 1% of hexazinone and sulfometuron methyl were measured in storm runoff. Herbicide was found in streams during storm events only (all herbicides wereµg/L in all true baseflow samples), and peak concentrations during runoff events persisted for relatively short times (\u3c 24 h). These results suggest that silvicultural herbicide applications implemented with contemporary BMPs are unlikely to result in chronic exposure of aquatic biota; therefore, herbicide use under these conditions is unlikely to degrade surface waters

Runoff and Sediment Losses from Annual and Unusual Storm Events from the Alto Experimental Watersheds, Texas: 23 Years After Silvicultural Treatments

Evaluating the potential impacts of intensive silvicultural practices on water quality is critical for establishing the long-term sustainability of contemporary forest management practices. From 1979 to 1985, a study involving nine small (~2.5 ha) forested watersheds was conducted near Alto, Texas in the upper western Gulf-Coastal Plain to evaluate the impacts then-current silvicultural practices on water quality. In the years following the study, silvicultural Best Management Practices (BMPs) including Streamside Management Zones (SMZs) and other erosion control practices evolved and questions arose about the applicability of earlier results to current practices. In 1999, these same watersheds were reinstrumented to evaluate the water quality effects of intensive silviculture using modern BMPs. Three years of pre-treatment data were collected to calibrate the watersheds. During the calibration phase, in June 2001, Tropical Storm Allison struck southeastern Texas, dumping almost 11.8 cm of rainfall on saturated soils in about 3 hours. This single storm event resulted in over 73% of the annual flow and over 95% of the annual sediment for 2001. In a little over three hours, the watersheds clearcut and chopped in 1980 generated over 2.5 times more sediment that the entire year following harvest and site-preparation. 1Comparisons of data from the 1979 Alto Watershed study with pretreatment data from the current study suggest that these watersheds have a high potential for geologic erosion even with mature forest cover. Large natural variation in runoff and sediment makes it difficult to detect treatment effects for these forested watersheds

Forest Clearcutting and Site Preparation On A Saline Soil In East Texas: Impacts On Water Quality

Three 0.02 hectare plot-watersheds were installed on a saline soil in the Davy Crockett National Forest near Apple Springs, Texas. Each plot was installed with an H-flume, FW-1 automatic water level recorder, Coshocton N-1 runoff sampler, and two storage tanks. One watershed was undisturbed forested and served a control, one was clearcut without any site-preparation, and the third was clearcut, V-blade sheared, windrowed, and vegetation regrowth was prevented for the first 2 years. A total of 274 storms were recorded during the four-year study period, 1989-1992. Average annual sediment losses for the study period were 55, 197, and 1,530 kilograms per hectare per year for the control, commercial clearcut, and sheared plots, respectively. These losses are about average for most studies conducted in East Texas and the Southeast and are well below average losses for all land uses in the Southeast. Sediment losses and surface runoff were significantly greater from the sheared plot-watershed than from the control and the commercial clearcut plots. Employing Wischmeier and Smith’s (1978) long-term average R-value for the USLE overestimated annual sediment yield for the study period, while two shortcut models developed in the United States resulted in more accurate predictions and are good substitutes for the long-term R-value. Total losses in surface runoff of PO4, NO3, NO2, TKN, K, Ca, Mg, Na, Al, Fe, Zn, and Cu were higher on the site-prepared plot watershed than the other two. Losses of PO4, TKN, and NO2 were higher on the commercial clearcut plot than the control. Losses were not high enough to adversely affect forest productivity. Concentrations of elements were generally below established USEPA surface water quality standards and were not high enough to adversely affect plant growth