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This study determined total suspended sediment (TSS) at six stream crossings that represented a range of site conditions and forest operations in the Piedmont of North Carolina. Two wood and three steel bridgemats and one culvert were installed to cross the streams. The road classes for the crossings included four temporary skid trails and two permanent forest haul roads. Baseflow and stormflow water samples and continuous stream discharge were measured using the upstream-downstream approach to determine the effects of stream crossings on TSS concentrations and loads. Upstream and downstream TSS concentrations from grab samples were not significantly different at any site during the study period. Baseflow TSS concentrations averaged 21.7 mg/l upstream and 21.1 mg/l downstream across study sites and periods. Stormflow TSS concentrations averaged 84.8 mg/l upstream and 84.7 mg/l downstream across all sites and periods. TSS loads were also comparable to exports from unharvested Piedmont watersheds and other stream crossing studies that used forestry best management practices (BMPs) to protect water quality, averaging 82 kg/ha/year upstream and 80 kg/ha/year downstream of the crossing. Our results add to the body of research indicating that stream crossing BMPs designed in mountain systems can be effectively applied to other regions to protect water quality. [ABSTRACT FROM AUTHOR]

This paired watershed study tested the effects of timber harvest on water quantity and quality in the North Carolina Piedmont physiographic region, four headwater watersheds at Hill Demonstration Forest (HF1, HF2, HFW1, and HFW2) and two at Umstead Research Farm (UF1 and UF2) were continuously monitored for discharge and water quality from 2007 to 2013. The HF1 and UF1 watersheds were dearcut (treatment), leaving a 15.2-m vegetated riparian buffer around the streams to protect water quality as described in the North Carolina Neuse River Basin Riparian Buffer Rule. HF2 and UF2 were uncut and used as reference watersheds. Merchantable timber was selectively removed from the riparian buffer, reducing tree basal area by 27% in HF1 and 48% in UF1. HF1 and HF2 were nested within HFW1; thus, HFW1 was considered a partial cut where 33% of the watershed area was harvested, and HFW2 was the reference. We found that discharge in treatment watersheds increased dramatically, averaging 240% in HF1 and 200% in UF1 and 40% in HFW1 during the postharvest period, 2011-2013. Total suspended sediment export in the treatment watersheds also increased significantly in HF1 after harvest, probably due to the increase of discharge and movement of in-channel legacy sediment. Stormflow peak nitrate reached its maximum concentration during the first 2 years after harvest in the treatment watersheds and then declined, corresponding to the rapid regrowth of woody ond herbaceous plants in the riparian buffer and uplands. We found that 36% of the UF1 streambank trees were blown down but did not cause a measurable increase in mean daily stormflow total suspended sediment concentration. Most buffer tree blowdown occurred during the first few years after a harvest. Bioclassification of benthic macroinvertebrates indicated that stream water quality remained good/fair to excellent in the treatment watersheds after the harvest. We conclude that the temporary increases in discharge were relatively large for the Piedmont region compared with those for other regions in the southeastern United States. However, the increases in channel sediment transport and nutrient exports associated with the hydrologic change did not have a measurable impact on the indicators of aquatic invertebrate community health or bioclassification rankings. [ABSTRACT FROM AUTHOR]

Forty-three bioretention cells (BRCs) throughout North Carolina were assessed for maintenance needs, soil media composition, and as-built surface storage volume to determine whether BRCs are typically constructed per their intended design specifications. Visual inspections identified hydric soils and redoximorphic features (indicators of prolonged anaerobic conditions) and quantified the occurrence of issues requiring maintenance. Particle-size distribution and permeability of soil media were measured at multiple locations within each cell, and topographic surveys were performed to calculate as-built surface storage volumes. Field drawdown tests were used to verify permeability measurements and assess overall BRC function. Of the studied cells, 22% contained redoximorphic features in the upper 30 cm, and 53% were in need of maintenance due to one or more factors. Although 71% of assessed cells failed to meet soil media particle-size distribution specifications, 98% of BRCs contained media with adequate or high permeability. Over half (65%) of cells were undersized vis-à-vis intended design, with 53% exhibiting moderately or severely undersized surface storage capacity. Discrepancies in average ponding depth and incorporation of inspection/maintenance programs significantly influenced the accuracy of as-built BRC storage volume; therefore, it is important for inspectors to verify that the bed elevations of BRCs have been accurately graded. Despite being typically undersized, it was concluded that most observed bioretention cells are meeting the hydrologic goals of North Carolina standards. [ABSTRACT FROM AUTHOR]

Indicator bacteria are a common source of impairment in surface waters in the United States. Urban storm water runoff has been identified as a contributor to elevated indicator bacteria concentrations. Six storm water control measures (SCMs) were monitored in Wilmington, North Carolina, for E. coli and enterococci. Monitored SCMs included two storm water wet ponds, two bioretention cells, and two storm water wetlands. Sandier watersheds in Wilmington potentially lead to differences in SCM performance for indicator bacteria compared to SCMs implemented in clayey watersheds. Results showed E. coli and enterococci concentration reductions between 70 and 98% for the two wet ponds and a bioretention cell with a 60-cm-deep fill media. Other SCMs showed poor removal of indicator bacteria, in some cases negative, with storm water wetlands performing the poorest overall for the three SCM types. Further analysis showed that SCMs with high concentration reductions tended to have geometric mean effluent concentrations lower than the U.S. EPA's target surface-water concentration for E. coli. Conversely, no SCM had a geometric mean effluent enterococci concentration lower than the U.S. EPA target value. SCM geometric mean effluent concentrations were typically higher during North Carolina's swimming season between the beginning of April and the end of October, although no statistically significant relationship could be found (p<0.05). Despite a lack of statistically significant relationships, the potential for higher effluent indicator bacteria concentrations from SCMs during the peak recreational season may have implications for both public health and watershed management and should be further evaluated by the scientific community. [ABSTRACT FROM AUTHOR]

An assessment of the performance of four level spreader-vegetative filter strip (LS-VFS) systems designed to treat urban storm-water runoff was undertaken at two sites in the Piedmont of North Carolina. At each site, a 7.6-m grassed filter strip and a 15.2-m half-grassed, half-forested filter strip were examined. Monitored parameters included rainfall, inflow to, and outflow from each LS-VFS system. A total of 21 and 22 flow-proportional water quality samples were collected and analyzed for the Apex and Louisburg sites, respectively. All studied LS-VFS systems significantly reduced mean total suspended solids (TSS) concentrations (p<0.05), with the 7.6 and 15.2-m buffers reducing TSS by at least 51 and 67%, respectively. Both 15.2-m VFSs significantly reduced the concentrations of total Kjeldahl nitrogen (TKN), total nitrogen (TN), organic nitrogen (Org-N), and NH4-N (p<0.05), whereas results were mixed for the 7.6-m VFSs. Significant pollutant mass reduction was observed (p<0.05) for all nine pollutant forms analyzed in Louisburg, which was caused by infiltration in the VFSs. The effects of VFS length and/or vegetation type are very important for pollutant removal, as effluent pollutant concentrations were lower (with one exception) for the 15.2-m VFSs. The median effluent concentrations for TN and total phosphorus (TP) for the four LS-VFSs were nearly always better than fair water quality benchmarks for the Piedmont of North Carolina, but only met good water quality metrics in one-half of the studied storm events. [ABSTRACT FROM AUTHOR]

Storm-water best management practices (BMPs) are typically assessed using the performance metric of pollutant concentration removal efficiencies. However, debate exists whether this is the most appropriate metric to use. In this study, a storm-water wetland constructed and monitored in the coastal plain of North Carolina is evaluated for water quality and hydrologic performance using four different metrics: concentration reduction, load reduction, comparison to nearby ambient water quality monitoring stations, and comparison to other wetlands studied in North Carolina. The River Bend storm-water wetland was constructed in spring 2007 and was monitored from June 2007 through May 2008. Twenty-four hydrologic and 11 water quality events were captured and evaluated. The wetland reduced peak flows and runoff volumes by 80 and 54%, respectively. Reductions were significant. Concentrations for the following pollutants increased: total kjeldahl nitrogen (TKN), NH4-N, total nitrogen (TN), and total suspended solids (TSS); inflow and outflow concentrations did not change for total phosphorus (TP), while only NO2-3-N and orthophosphorus (OP) concentrations were lower at the outlet. Using a load reduction metric, results were strikingly different, showing positive load reductions of 35, 41, 42, 36, 47, 61, and 49% for these respective pollutants: TKN, NO2-3-N, NH4-N, TN, TP, OP, and TSS. When comparing the effluent concentrations from the wetland to ambient water quality in the Trent River, all effluent nitrogen species concentration were either similar or lower. TP and TSS concentrations leaving the wetland were higher than ambient water quality data. Finally, by comparing pollutant concentrations among different North Carolina wetlands, it is apparent the River Bend wetland received relatively 'clean' water and released water with pollutant concentrations comparable to all other studies examined. Major conclusions from this study include: (1) storm-water wetlands sited in sandier soils (such as those of the North Carolina coastal plain) should be considered a low impact development tool and (2) the selection of performance metric has a pronounced bearing on how a BMP's performance is perceived. Sole reliance on a concentration reduction metric is discouraged. [ABSTRACT FROM AUTHOR]

With increasing development in areas of trout sensitive waters, the effect of urban storm-water runoff temperature on the aquatic ecosystem has become a concern. A study was conducted in western North Carolina, along the southeastern extent of U.S. trout populations, to determine the effect of storm-water wetlands and wet ponds on the temperature of urban storm-water runoff. Measurements included temperature at the inlets, outlets, and at several depths within the best management practices (BMPs). Parking lot runoff temperatures were significantly higher than the 21°C temperature threshold for trout during peak summer months and water temperatures consistently increased from the inlet to the outlet in the storm-water wetland and wet pond, implicating these BMPs as sources of thermal pollution. Despite similar inflow temperatures, effluent temperatures from the wet pond were significantly warmer than those from the storm-water wetland for the period from June to September. Substantial cooling was observed as runoff was conveyed from the parking surface to the BMPs through buried pipes, which could be incorporated into BMP design to achieve thermal pollution mitigation goals. Temperatures at the bottom of the water columns were cooler than water leaving the current outlet structures, providing support for the installation of modified outlet structures in regions with cold water fisheries. [ABSTRACT FROM AUTHOR]

Storm-water experts agree that the currently used best management practice (BMP) percent removal methodology metric has many flaws, and some have suggested using a BMP effluent concentration metric. This case study examines establishing an effluent target concentration for BMPs that relates to the health of macroinvertebrates in the receiving water. In North Carolina, 193 ambient water quality monitoring stations were paired with benthic macroinvertebrate health ratings collected in very close proximity. Water quality for the sites ranged from excellent to poor and was divided into three distinct ecoregions: Mountain, Piedmont, and Coastal. Statistically significant relationships were found in one or more ecoregions for dissolved oxygen, fecal coliform, NH3, NO2-3-N, total Kjeldahl nitrogen, total nitrogen (TN), and total phosphorus (TP). BMPs can then be selected and designed to meet these target effluent concentrations. Based upon this research, a development, and therefore set of BMPs, in Piedmont North Carolina could be required to release TN and TP effluent concentrations of 0.99 mg/L and 0.11 mg/L, respectively. These concentrations are both associated with “good” benthos health. The new method was most effective in the Piedmont ecoregion, however with more data collection, the Mountain and Coastal ecoregions may also benefit. [ABSTRACT FROM AUTHOR]

Three storm-water wetlands in series were monitored in a heavily urbanized 12.5 ha watershed in Mooresville, North Carolina. Monitoring of this system allowed an examination of the diminishing returns provided by three successive best management practices (BMPs) of a similar type. At least 80% of the total concentration reduction for all pollutants occurred within the first wetland cell. Only the first wetland cell significantly (p<0.05) reduced all pollutants tested. No pollutant was significantly reduced from the outlet of Wetland Cell 2 to the outlet of Wetland Cell 3 (p<0.05). Median complete system (outlet of Wetland Cell 3) effluent concentrations for total suspended solids, total phosphorus, total nitrogen, and turbidity were 8, 0.09, 0.73 mg/L, and 10 NTU, respectively, which compared favorably to published results. Organic nitrogen generated from wetland vegetation seemed to result in a background source of nitrogen in the wetlands, supporting the idea of an irreducible concentration for nitrogen in these systems. The results indicate that the successive BMPs in a series do not perform as well as the first when each BMP uses similar removal mechanisms. [ABSTRACT FROM AUTHOR]

Program OPEN (Odor, Pathogens, and Emissions of Nitrogen) was an integrated study of the emissions of ammonia (NH3), odor and odorants, and pathogens from potential environmentally superior technologies (ESTs) for swine facilities in eastern North Carolina. This paper, as part of program OPEN, focuses on quantifying emissions of NH3 from water-holding structures at two of the best ESTs and compares them with the projected emissions from two conventional lagoon and spray technologies (LSTs). The evaluated ESTs are: (1) Super Soils at Goshen Ridge; and (2) Environmental Technologies at Red Hill. The water-holding structures for these two ESTs contained no conventional anaerobic lagoon. A dynamic flow-through chamber was used to measure NH3 fluxes from the water-holding structures at both the ESTs and at the conventional LST farms. In order to compare the emissions from the water-holding structures at the ESTs with those from the lagoons at the conventional sites under similar conditions, a statistical-observational model for lagoon NH3 emissions was used. A mass-balance approach was used to quantify the emissions. All emissions were normalized by nitrogen-excretion rates. The percentage reductions relative to the conventional lagoons were calculated for the two ESTs. Results showed substantial reductions in NH3 emissions at both ESTs. Super Soils had reductions of 94.7% for the warm season and 99.0% for the cool season. Environmental Technologies had slightly larger reductions of 99.4% and 99.98% for the cool and warm season, respectively. As a result of such large reductions in ammonia emissions, both technologies meet the criteria to be classified as ESTs for ammonia emissions. [Copyright &y& Elsevier]

The article discusses findings of a study which evaluated a combination of best management practices used on two agricultural watersheds in North Carolina. The research is aimed at estimating the combined reductions that can be achieved for tobacco cultivation. A significant source of pollutants to surface water is the storm runoff from agricultural fields. The three best management practices for flue-cured tobacco production include reduced-till versus conventional tillage, grassed field-side filter zones and forested filter zones.

This paper shows how farm economics information that is widely available can be used to help guide local resource managers and watershed groups in their efforts to design cost-effective programs to improve water quality. The focus is on the economic elements driving farmer and landowner decisions and how those compare with incentive payments to alter these decisions. The approach is illustrated for the case of Best Management Practices (BMPs) mandated for nitrogen control in the Neuse River Basin in North Carolina. The empirical research shows that the economics of the BMPs are very different for the three regions in the basin as distinguished by physiographic conditions. Economic differences in implementing BMPs should be taken into account by state and federal authorities when they are determining cost-share programs. The research also shows that the cost-share payments offered for grass buffers might not be in line with the relative reduction in nitrogen emission offered by this BMP. [ABSTRACT FROM AUTHOR]