Effectiveness of best management practices in improving stream ecosystem quality

ABSTRACT: To quantify the effectiveness of best management practice (BMP) implementation on runoff, sediment, and nutrient yields from a watershed, the Nomini Creek watershed and water quality monitoring project was initiated in 1985, in Westmoreland County, Virginia. The changes in nonpoint source (NPS) loadings resulting from BMPs were evaluated by comparing selected parameters from data series obtained before, during, and after periods of BMP implementation. The results indicated that the watershed‐averaged curve number, sediment, and nutrient (N and P) concentrations were reduced by approximately 5, 20, and 40 percent, respectively, due to BMP implementation. The nutrient yield model developed by Frere et al. (1980) was applied to the water quality parameters from 175 storms, but it failed to adequately describe the observed phenomena. Seasonal changes in nutrient availability factors were not consistent with field conditions, nor were they significantly different in the pm‐ and post‐BMP periods. An extended period of monitoring, with intensive BMP implementation over a larger portion of the watershed, is required to identify BMP effectiveness.

There is growing interest in evaluating the impacts at the watershed scale of agricultural best management practices (BMPs) designed to improve water quality. Many approaches to impact assessment require detailed information about actual BMP use by farmers and landowners in a watershed. This paper examines the strengths and weaknesses of using formal USDA Natural Resources Conservation Service records of conservation program participation as an indicator of spatial and temporal patterns of BMP implementation and maintenance. Field interviews with conservation program participants revealed potential limitations with official records regarding (1) documentation of the incidence of successful BMP implementation, (2) the nature of the BMPs that were implemented, (3) accurate measurement of the timing and location of BMP implementations, and (4) information about the long-term use and maintenance of implemented BMPs. The results suggest that official records should be field-verified before being used as indicators of BMP use. The findings also point to a larger need for development of more robust and accurate systems for tracking BMP implementation and maintenance over periods of time.

Assessing multivariate effect of best management practices on non-point source pollution management using the coupled Copula-SWAT model

113 Southern awareness and implementation of pasture best management practices

ABSTRACTOperational stream crossings on forest roads and skid trails are potential sediment delivery areas from timber harvests that can negatively affect water quality if best management practices (BMPs) are not sufficiently implemented. Virginia has three major physiographic regions (Mountains, Piedmont, Coastal Plain), and the diverse topographies require some specificity of BMP guidelines for water quality protection. Furthermore, truck roads and skid trails utilize different drainage and erosion control BMPs to maintain sufficient working conditions and access to timber. As a result, differing BMP approaches and implementation levels for roads and trails inherently have different associated costs. We evaluated BMP implementation levels on 154 stream crossing approaches (3 regions × 2 road types × a minimum of 25 stream crossings). We categorized the crossings as BMP− (failed to meet recommended BMPs), BMP-standard (met recommended guidelines), or BMP+ (exceeded recommended guidelines). We estimated hypothetical costs for elevating BMP− stream crossings to BMP-standard and BMP+ and costs of elevating BMP-standard to BMP+. Average BMP implementation audit scores for stream crossings were 88% on skid trails and 82% on truck roads. To upgrade from a BMP− to BMP-standard, the cost-benefit ratio ($/Mg of sediment prevented) averaged $248.58/Mg for skid trails and $670.33/Mg for truck roads. Enhancement from BMP-standard to BMP+ level is less economically efficient and BMP implementation efficacy at stream crossings appears to plateau at the BMP-standard level.

Nonpoint source transport of nutrients, sediment, and pathogens from agricultural activities is a major concern in the Ozark Highlands of Northwest Arkansas; rolling hills in this region are home to thousands of poultry farms and pastures that produce forage for numerous beef and dairy cattle, resulting in an abundance of animal manure. The predominant use of manure in the area has been as a fertilizer for perennial forage crops. There is growing concern that excess land applications of the manure can lead to surface and ground water pollution due to increased runoff losses of sediment, nutrients, and pathogens. Additionally, this region is experiencing a rapid urbanization resulting in the loss of forest and pasture lands and adding to existing concerns regarding nonpoint pollution. There has, however, been some best management practice (BMP) implementation in the area over the years, these mainly pertaining to nutrient and grazing management. This study seeks to quantify the effects of implementation, timing, and spatial distribution of the BMPs on sediment and nutrient loss reduction and watershed ecological integrity, with a focus on Lincoln Lake watershed, a primarily agricultural watershed in NW Arkansas. An analysis of historical land use and BMP implementation for this watershed showed a 9% increase in urban areas and an 11% decrease in pastured areas during the years 1992-2004. About 10% of the watershed was in a transitional land use, comprising newly cleared forests and abandoned pastures. Over the same time period, BMP implementation increased from <1% to 34% of the watershed area, extending across most of the pasture lands in the watershed. During this time, sediment and total phosphorus losses declined by 22% and 4% respectively, while total nitrogen losses increased by 11%, based on analyses of historical in-stream water quality data. Because of the overlap between BMP implementation and occurrence of land use changes, detailed modeling analyses were found necessary to help distinguish between the effects of BMPs and those due to land use changes. This paper discusses the assessment of BMP impacts based on historical data, as well as on preliminary modeling analyses using the Soil and Water Assessment Tool (SWAT).

Forest residue utilization for energy has increased in the southeastern United States and additional increases are anticipated. However, such removals generate concerns regarding potential accelerated erosion and nutrient drains, which could affect site productivity and stream water quality. To address erosion and water quality concerns, postharvest erosion rates, operational feature areas, best management practice (BMP) implementation, residual ground cover, soil disturbance, and forest residue concentrations were evaluated on ten biomass and ten conventional clearcut harvests in Virginia’s Coastal Plain. No significant differences in erosion rates (P = 0.4727) were observed between biomass (0.71 tons ac-1 yr-1) and conventional (0.61 tons ac-1 yr-1) harvests. BMP compliance percentages were similar (P = 0.6776) for both biomass (88.54%) and conventional (90.99%) harvests. BMP implementation scores were determined to be a significant predictor of erosion rates (P &amp;lt; 0.0001). A significant reduction (28%) in postharvest residue concentrations was observed for biomass (10.22 tons ac-1) versus conventional harvests (14.24 tons ac-1) (P = 0.0173). Scores for BMP implementation and erosion rates were not significantly different between treatments, indicating that sufficient residual biomass exists for appropriate implementation of BMPs. BMPs provided similar erosion protection on both biomass and conventional clearcut harvests.Study Implications: Forest residues are widely used to cover and stabilize bare soil as best management practices (BMPs) for erosion control. The expanding bioenergy market has raised concerns that overutilization of forest residues may occur. Comparisons of biomass and conventional harvests in the Coastal Plain of Virginia revealed few significant postharvest differences. Implementation of existing water quality BMPs is important for minimizing erosion on biomass harvests; however, the development of biomass harvesting guidelines in addition to current state BMPs appears unnecessary under current harvesting practices. Harvest residue management should be conducted to ensure adequate supplies of woody debris remain for site protection.

Forestry best management practices (BMPs) reduce sedimentation by minimizing soil erosion and trapping sediment. These practices are particularly important in relation to road construction and use due to the heightened potential for sediment delivery at stream crossings. This study quantifies the implementation and effectiveness of BMPs at 75 randomly selected forest road stream crossings on recent timber harvests in the Mountains, Piedmont, and Coastal Plain regions of Virginia. Road characteristics at stream crossings were used to estimate erosion using the Universal Soil Loss Equation for Forests and the Water Erosion Prediction Project for Roads. Stream crossings were evaluated based on the Virginia Department of Forestry (VDOF) BMP manual guidelines and categorized as BMP−, BMP‐standard, or BMP+ based on the quality of road template, drainage, ground cover, and stream crossing structure. BMP implementation scores were calculated for each stream crossing using VDOF audit questions. Potential erosion effects due to upgrading crossings were estimated by adjusting ground cover percentage and approach length parameters in the erosion models. Results indicate that erosion rates decrease as BMP implementation scores increase (p &lt; 0.05). BMP‐standard and BMP+ ratings made up 83% of crossings sampled, with an average erosion rate of 6.8 Mg/ha/yr. Hypothetical improvements beyond standard BMP recommendations provided minimal additional erosion prevention.

Excess nutrients and herbicides remain two major causes of waterbody impairment globally. In an attempt to better understand pollutant sources in the Big Sandy Creek Watershed (BSCW) and the prospects for successful remediation, a program was initiated to assist agricultural producers with the implementation of best management practices (BMPs). The objectives were to (1) simulate BMPs within hotspots to determine reductions in pollutant loads and (2) to determine if water-quality standards are met at the watershed outlet. Regression-based load estimator (LOADEST) was used for determining sediment, nutrient and atrazine loads, while artificial neural networks (ANN) were used for determining E. coli concentrations. With respect to reducing sediment, total nitrogen and total phosphorus loads at hotspots with individual BMPs, implementing grassed waterways resulted in average reductions of 97%, 53% and 65% respectively if implemented all over the hotspots. Although reducing atrazine application rate by 50% in all hotspots was the most effective BMP for reducing atrazine concentrations (21%) at the gauging station 06883940, this reduction was still six times higher than the target concentration. Similarly, with grassed waterways established in all hotspots, the 64% reduction in E. coli concentration was not enough to meet the target at the gauging station. With scaled-down acreage based on the proposed implementation plan, filter strip led to more pollutant reductions at the targeted hotspots. Overall, a combination of filter strip, grassed waterway and atrazine rate reduction will most likely yield measureable improvement both in the hotspots (&gt;20% reduction in sediment, total nitrogen and total phosphorus pollution) and at the gauging station. Despite the model’s uncertainties, the results showed a possibility of using Soil and Water Assessment Tool (SWAT) to assess the effectiveness of various BMPs in agricultural watersheds.

The effects of buffer strips and bioretention facilities on agricultural productivity and environmental quality in Central Africa

Uncertainty of best management practice (BMP) effectiveness is an important factor in the development of watershed management plans. This study explored the uncertainty of BMP effectiveness in reducing total nitrogen (TN) load owing to the uncertainty in hydrological parameters, thereby improving their reliability. A watershed model, annualized agricultural non-point source pollution (AnnAGNPS), was employed to evaluate the effectiveness of the four potentially feasible BMPs (i.e., riparian buffer, fertilization reduction, no-tillage, and parallel terraces) in the Shanmei Reservoir watershed, located in the southeastern coastal region of China. Annual and seasonal uncertainty variations in BMP effectiveness were evaluated based on ten parameter sets selected from 1000 parameter groups using Latin hypercube sampling. The results showed that the uncertainty of BMP effectiveness in reducing the TN load was larger than the uncertainty of TN load simulation at annual and seasonal time scales. The BMP effectiveness tended to be higher in summer than in the other seasons. The uncertainty of BMP effectiveness varied seasonally, and it was always lower in summer for most BMPs. This indicated that the impact of BMPs on reducing TN load was more effective, with a higher reduction rate and lower uncertainty in summer. Among the BMPs, the parallel terrace was the most effective measure for reducing TN load since it had the highest reduction rate and relatively low uncertainty. Although this study is a case study, it can provide a scientific reference for decision-making in uncertain situations when AnnAGNPS is applied for water quality simulations.

Conventional agricultural practices produce nonpoint source water pollution. The implementation of Best Management Practices (BMPs) in a watershed plays a vital role in improving water quality. Assessing the effectiveness of BMPs requires both monitoring and modelling. A nonpoint source management water policy change was introduced in Minnesota to monitor and model small watersheds for 16 years to determine the effectiveness of BMPs. Monitoring small watersheds alone has not shown water quality improvement; there has been a lack of observable improvement in water quality due to the fragmentation of landscape BMPs and lag time. Dobbins Creek was selected as a sentinel watershed to track water quality for a period longer than a few years to account for lag time. Dobbins Creek is a small agricultural watershed located in the headwaters of the Cedar River. This is an important large watershed that contributes to Gulf of Mexico hypoxia. A monitoring and modelling program were implemented in 2016 that included the analysis of sediment and nutrients at strategic locations in the watershed. We demonstrate how to show an exceedance of water quality standards primarily during stormflow before major BMP implementation. Over time we anticipate water quality changes with land use changes and financial incentives, but the proper approach must be designed and financially supported to be truly effective

Use of a calibrated SWAT model to evaluate the effects of agricultural BMPs on sediments of the Kalaya river basin (North of Morocco)

Analysis of daily phosphorus-yield and streamflow data collected before and after implementation of agricultural best-management practices in the Johnson Brook watershed in south-central Maine indicated statistically significant reductions in phosphorus loading in all flow categories. Reduction of median loadings for five flow categories ranged from 26 to 90 percent. The annual total phosphorus yield was reduced 17 percent after implementation of the best-management practices. The observed phosphorus yield reduction is considerable because of two streamflow factors. First, the period after implementation of the best-management practices had eight more storms. Periods of storm runoff in the postimplementation period had 31 days with greater average streamflow and a maximum daily streamflow more than three times greater than those observed in the preimplementation period. Second, the annual streamflow was 128 percent greater in the year after the management practices were implemented. Because the potential for phosphorous transport increases with runoff, and greater yields are possible when the volume of water increases, a higher phosphorous yield would be expected in the postimplementation period then during the preimplementation period, if other factors had remained unchanged. The reductions in phosphorous yield in the study area are not expected to have a significant effect on the eutrophic conditions observed in Lovejoy Pond. Phosphorous concentrations in the pond will continue to be capable of supporting algal blooms. However, the intensity and duration of blooms are expected to be less than those observed before best-management practice implementation. 1 Hydrologist, U.S. Geological Survey, Augusta, Maine 2 Biologist, Maine Department of Environmental Protection, Augusta, Maine

Florida's unique combination of sub-tropical climate, sandy soils, high-value crops, and shallow water tables have made the development and implementation of best management practices (BMPs) to reduce environmental impacts from agricultural production a challenge. Most of the BMP development has followed commodity lines, with the primary programs developed to date in the following: citrus, sod, vegetables, equine, agronomic crops, cow calf operations, silviculture, container nurseries, forage grasses, aquaculture, and leatherleaf ferns. BMP programs have been developed for the golf course and landscape industries in addition to programs focused on lawn care, yards, and homeowners associations. Each of the BMP programs are designed to reduce impacts to ground and surface waters by reducing loadings of nutrients, pesticides, sediment, and flow volume running off the properties. This paper summarizes the BMP processes that have produced a BMP manuals, workshops, on-farm demonstrations, public education campaigns, and extensive agricultural worker training programs. This paper also presents lessons learned about developing consensus among the diverse interests involved in developing BMPs.