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In this study, a bioassessment was conducted to determine the effectiveness of best management practices (BMPs) implemented in farms in the Upper Delaware River watershed, NY (USA). Diatom and macroinvertebrate communities were analyzed across 17 low-order streams, designated as reference, BMP, or non-BMP. Streams lacking improvements (non-BMP) had significantly greater specific conductance, pH, TDP, NH-N, and NO-N than did reference streams. Diatom model affinity (DMA) values were significantly greater in reference and BMP streams than in non-BMP streams; non-BMP streams bordered on a 'severely impacted' rating. The Trophic Diatom Index (TDI) varied two-fold among stream classes, with non-BMP > BMP > reference. TDI and DMA values were highly correlated, and both varied significantly with conductance, TDP, NH-N, and NO-N. Macroinvertebrate taxa, EPT richness, and Simpson's diversity did not differ significantly among stream classes. Macroinvertebrate metrics (HBI, Bioassessment Profile, Percent Model Affinity) varied by stream class, but none indicated greater water quality in BMP sites. Nonetheless, each correlated significantly with conductance and TDP in the directions predicted by each model. Our data suggest that diatoms are more sensitive to moderate increases in nutrients, conductivity, and pH in high-gradient agricultural streams, and may be more useful in assessing stream management practices. [ABSTRACT FROM AUTHOR]

Best management practices (BMPs) have been implemented on a farm-by-farm basis within the Cannonsville Reservoir watershed (CRW) as part of a New York City watershed-wide BMP implementation effort to reduce phosphorus (P) loads to the water supply reservoirs. Monitoring studies have been conducted at selected locations and at the watershed outlet on one of the farms, which spans an entire subwatershed within the CRW, with the aim of quantifying effectiveness of the BMPs installed on the farm. This study applied the Soil and Water Assessment Tool (SWAT) and a recently developed BMP characterization tool to the farm over pre- and post-BMP installation periods with the object of determining the extent to which model results incorporating all installed BMPs match observed data, and the individual impact of each of the BMPs installed on the farm. The SWAT model generally performed well at the watershed level for flow, sediment, and phosphorus simulations. Annual Nash-Sutcliffe (NS) coefficients for the components ranged between 0.56 and 0.80, while monthly NS coefficients ranged between 0.45 and 0.78. The model also performed well at the field level, with simulated in-field P loads closely matching observed data. Because the fields had various combinations of BMPs installed on them, it was difficult to separate out individual BMP impacts based on SWAT simulations. It was, however, possible to determine the effects of BMP combinations such as nutrient management plans and rotations (31% dissolved P; 25% total P). For dissolved P, integration of BMP tool efficiencies allowed individual BMP impacts to be incorporated while still maintaining the same level of representation as was obtained using model simulations. As the SWAT model is often used with little or no post-BMP data to verify simulation results, this study served to validate SWAT model suitability for evaluating BMP impacts. The BMP tool was found to suitably complement the model by providing insights into individual BMP impacts, and providing BMP efficiency data where the model was lacking. [ABSTRACT FROM AUTHOR]

The article discusses a study on the impact of implementing best management practices (BMPs) at a dairy farm in New York. In order to simulate phosphorus loading at the dairy farm, a distributed watershed model called Variable Source Loading Function (VSLF) was used. The study found that loss of dissolved phosphorus (DP) from agricultural landscapes was reduced with the VSLF model. It suggested the implementation of a long-term water quality monitoring approach to determine BMPs with significant impacts.

For a number of years, best management practices (BMPs) have been implemented within the Town Brook watershed as part of a watershed wide effort to reduce phosphorus losses to the New York City water supply reservoirs. Currently, there are no quantitative indications of the effectiveness of these practices at the watershed scale. Additionally, work is needed to evaluate management practice solutions for costs in relation to effectiveness. In this study we develop a methodology for evaluating management solutions to determine the best way(s) to select and place management practices so that pollutant removal targets are met at minimum cost. The study combines phosphorus losses as simulated by the Soil and Water Assessment Tool (SWAT), management practice effectiveness estimates from a predeveloped characterization tool, and practice costs in optimizations using a genetic algorithm. For a user defined target phosphorus removal (60 percent for this study), optimization favors nutrient management plans, crop rotations, contour strip cropping, and riparian forest buffers; the most cost effective scenario achieves a cost effectiveness of $24/kg phosphorus removal per year compared to the $34/kg phosphorus removal per year associated with the current basic implementation scheme. The study suggests that there is a need to evaluate potential solutions prior to implementation and offers a means of generating and evaluating the solutions. [ABSTRACT FROM AUTHOR]

Identifying phosphorus (P) source areas and transport pathways is a key step in decreasing P loading to natural water systems. This study compared the effects of two modeled runoff generation processes - saturation excess and infiltration excess - on total phosphorus (TP) and soluble reactive phosphorus (SRP) concentrations in 10 catchment streams of a Catskill mountain watershed in southeastern New York. The spatial distribution of runoff from forested land and agricultural land was generated for both runoff processes; results of both distributions were consistent with Soil Conservation Service-Curve Number (SCS-CN) theory. These spatial runoff distributions were then used to simulate stream concentrations of TP and SRP through a simple equation derived from an observed relation between P concentration and land use; empirical results indicate that TP and SRP concentrations increased with increasing percentage of agricultural land. Simulated TP and SRP stream concentrations predicted for the 10 catchments were strongly affected by the assumed runoff mechanism. The modeled TP and SRP concentrations produced by saturation excess distribution averaged 31 percent higher and 42 percent higher, respectively, than those produced by the infiltration excess distribution. Misrepresenting the primary runoff mechanism could not only produce erroneous concentrations, it could fail to correctly locate critical source areas for implementation of best management practices. Thus, identification of the primary runoff mechanism is critical in selection of appropriate models in the mitigation of nonpoint source pollution. Correct representation of runoff processes is also critical in the future development of biogeochemical transport models, especially those that address nutrient fluxes. [ABSTRACT FROM AUTHOR]

Studies the reductions in phosphorus loading attributable to an extensive program of agricultural best management practices (BMP) implemented on a working dairy farm in the watershed of a water supply reservoir in New York City. Quantification of the BMP treatment effects; Use of statistical formulas to estimate the analytucal power and minimum detectable treatment effect associated with the paired watershed analysis; Event flow volumes at the farm watershed.

A best management practice (BMP) tool was developed as a part of an effort to address the phosphorus (P) pollution and associated eutrophication problem affecting the Cannonsville Reservoir, part of the New York City water supply system. P reaching the reservoir is thought to emanate from runoff from the surrounding farms, mainly as a result of manure spread on these farms. Efforts to address the problem have involved implementation of BMPs on the watersheds; however, the effectiveness of these practices is not known. This study establishes a means of estimating BMP effectiveness, based on data available in the literature, and develops a tool that allows users to obtain BMP effectiveness estimates for their respective site soil and slope conditions. The tool offers stand-alone capabilities and has the potential to be linked to a GIS. An example is presented to illustrate tool application for effectiveness-based BMP selection, with a focus on a farm within the New York City watersheds. [ABSTRACT FROM AUTHOR]

Management practices may affect the potential for nitrate leaching from agricultural systems. Two studies are discussed that used plot-size lysimeters on loamy sand and clay loam soil in Northern New York. One was conducted from 1991 to 1994 and involved sod plowing and the use of three rates of fertilizer on maize (Zea mays L.). The other study was conducted from 1997 to 2000 and quantified N-leaching losses under maize and orchardgrass (Dactylis glomerata L.) as affected by the timing of manure application. These studies showed that timing and rate of N fertilizer and manure additions, timing of green-manure incorporation, and soil type strongly influenced N-leaching losses. Losses from fall-applied N sources were high, especially on coarse-textured soils. Lower N losses in fine-textured soils were primarily the result of higher denitrification losses, rather than reduced percolation rates. It was concluded that the current N Leaching Index ignores important processes and requires a more dynamic approach that includes management factors. In the interim, we established a set of best management practices for N to reduce the potential for N leaching losses. [ABSTRACT FROM AUTHOR]