Transmission of extended-spectrum β-lactamase (ESBL)–producing Enterobacteriaceae in households outweighs nosocomial dissemination in the non-outbreak setting. Importation of ESBL producers into the hospitals is as frequent as transmission during hospital stay. ESBL– Klebsiella pneumoniae might be more efficiently transmitted within the hospital than ESBL– Escherichia coli .

Hydrologic and hydraulic modeling in the USEPA Stormwater Management Model (SWMM) were used to examine the effectiveness of typical stormwater management practices in reducing the potential for stream erosion. Fifty-year continuous simulations were used to produce flow duration curves and stream erosion rates for a variety of critical shear stress values representative of both cohesive and non-cohesive sediments. An excess shear stress erosion potential index was used to evaluate changes in erosion between undeveloped conditions of a 10 hectare watershed and four variations of post-development stormwater control. Evaluation of flow duration curves showed that when development takes place, the duration of mid- to low-range discharges increase significantly, especially when detention practices are applied. In channels with low entrainment thresholds for bed and bank materials, e.g. sands and highly erodible clays, the significant increase of the duration of mid- to low-range discharges results in erosion potential index values greater than two regardless of the detention practices used. Overcontrol detention resulted in erosion potential index values of less than one, indicating a loss of erosion potential for bed materials such as most gravels (d(s) > 6 mm) and resistant clays that have critical shear stress values greater than four Pa.

No abstract

Urbanization of a watershed increases impervious area, and consequently increases stormwater runoff. When left uncontrolled, these increases in stormwater runoff cause downstream flooding, accelerate channel erosion, and impair aquatic habitat. Increases in the magnitude and duration of stormwater runoff that accompany uncontrolled development allow a stream to carry more sediment than it could prior to watershed development. When a watershed cannot supply the stream with the volume of sediment it has the capacity to carry, channel degradation may occur in the form of incision, lateral migration or, or a combination of both. This study evaluates the potential impact of watershed development on sediment transport in a prototype headwater stream subjected to typical residential development. Event based and continuous simulations, using 50 years of hourly rainfall records were performed with two climatically different locales. The first in the semiarid climate of Fort Collins, Colorado and the other in a typical southeastern climate, Atlanta, Georgia. Five conditions were evaluated for the study watershed, including: current (undeveloped) conditions, fully developed conditions, without stormwater controls, and fully developed conditions with stormwater controlled using (a) the City of Fort Collins flood control standard, (b) the City of Fort Collins flood control standard and water quality capture volume (WQCV) criteria, and, (c) using common standards of practice in the United States: control of the 100-and 2-year storms to historic peak discharge rates and control of the WQCV. For each scenario examined, sediment transport potential is evaluated for two noncohesive soil types: medium gravel and medium sand.

The Rouge Project has monitored discharge at 13 continuous flow gauging stations serving drainage areas varying from nine to 410 square miles for the past 11 years as a means of evaluating existing conditions and tracking progress. This study evaluates the flow regime of the Rouge Watershed including the analysis of a decade or more of data, and status with regard to ecological targets. The temporal resolution of in-stream flow data required to establish long-term trends is also investigated by comparing flow exceedence frequency curves developed using 15-minute, hourly average, and daily average flow data and the Mann-Kendall analysis for trend at varying exceedence classes. Trend analysis of flow frequencies indicates that flow values have decreased, or have remained the same over the period of record examined for each flow monitoring station along the Main, Upper, and Middle Rouge Rivers. A strong trend of increasing flows was observed in the Lower Rouge River for flows in the low to midrange, primarily due to increased wastewater treatment plant discharges. The direction of trends predicted by flows measured at a 15-minute, hourly-average, and daily average time scale did not vary, although trend strength varied significantly. Fewer differences in trend strength were observed between 15-minute and hourly-average data than between 15-minute and daily-average data, indicating that hourly data are adequate for trend analysis. The overall number of ecological flow targets that were met did not increase at nine Rouge flow monitoring stations between the time periods of 1994-1999 and 2000-2005. Summer improvements of peak flows were observed at one station along the Lower Rouge River. Flows fell from within the acceptable tolerance range to below lower bounds at two stations, indicating a decrease in baseflow at those stations.