Showing papers on "Nonpoint source pollution published in 1987"

Generalized watershed loading functions for stream flow nutrients

Abstract: Loading functions are proposed as a general model for estimating monthly nitrogen and phosphorus fluxes in stream flow The functions have a simple mathematical structure, describe a wide range of rural and urban nonpoint sources, and couple surface runoff and ground water discharge Rural runoff loads are computed from daily runoff and erosion and monthly sediment yield calculations Urban runoff loads are based on daily nutrient accumulation rates and exponential wash off functions Ground water discharge is determined by lumped parameter unsaturated and saturated zone soil moisture balances Default values for model chemical parameters were estimated from literature values Validation studies over a three-year period for an 850 km2 watershed showed that the loading functions explained at least 90 percent of the observed monthly variation in dissolved and total nitrogen and phosphorus fluxes in stream flow Errors in model predictions of mean monthly fluxes were: dissolved phosphorus - 4 percent; total phosphorus - 2 percent; dissolved nitrogen - 18 percent; and total nitrogen - 28 percent These results were obtained without model calibration

ES Feature: Pollution from Nonpoint Sources.

Abstract: Efforts to protect water from nonpoint source pollution are underway, but much remains to be done. Recent water quality evaluations and landmark legislation place nonpoint source (NPS) control programs at a pivotal point. The Clean Water Act (CWA) Reauthorization, passed by Congress in Feb. 1987 specifically addresses NPS pollution for the first time. It directs states to submit to EPA a list of waters not meeting CWA goals because of NPS pollution and to submit an NPS management program for those waters. States are required to identify land use sectors that cause major NPS problems. Some professionals declare nonpoint sources to be the major reason for not reaching water quality goals.

A geographic information system to predict non‐point source pollution potential

Abstract: Bacterial densities (total coliform, fecal coliform, and fecal streptococci) and suspended solids in runoff from a feedlot, pasture, and corn field were measured. Densities of fecal coliform were highest from the feedlot but were 1000 to 10,000 times greater than the water quality standard for swimmable waters from all three land uses. Densities of fecal streptococci were highest from the corn field, which suggests that wildlife are the source of bacteria. Fecal coliform/fecal streptococci ratios distinguished cattle from wildlife as the source of bacterial pollution both among land uses and among seasons of the year. Suspended solids concentrations in runoff ranged from 423 to 925 mg/l and were highest from the corn field. A Geographic Information System (GIS), which utilizes a raster or grid-cell format, was developed to include algorithms associated with non-point source pollution. The system accepts digitally mapped information on soil type, topography, and land use. It calculates characteristics such as slope and slope length, and relates these characteristics to soils and land use parameters in order to produce three dimensional maps of runoff potential, sediment pollution potential, and bacterial pollution potential. It offers the advantages of retaining the geographic character of pollution potential information and of conveying in three-dimensional graphical terms the effects of topography, soil type, land use, and land management practices.

Optimizing nonpoint source controls in water quality regulation

Abstract: A stochastic programming framework is developed to evaluate the economic implications of reliability criteria and multiple effluent controls on nonpoint source pollution. An integrated watershed simulation model is used to generate probability distributions for agricultural effluents in surface and ground water resulting from agricultural practices. Results from the planning model indicate that reliability and multiple effluent constraints significantly increase the cost of nonpoint controls but the effects vary by control alternative. The analysis indicates that an evaluation of multiple water quality objectives can be an important planning tool for designing nonpoint source controls for innovative programs to promote cost-effective water quality regulation.

Allocative Implications of Comparisons Between the Marginal Costs of Point and Nonpoint Source Pollution Abatement

Abstract: This paper examines the possible use of information on the relative marginal costs of point and nonpoint source water pollution abatement to assess the efficiency implications of shifting a greater portion of the burden for water quality protection to nonpoint sources. The inherent uncertainty about the effects of changes in resource allocation for nonpoint pollution abatement on nonpoint pollution loads is recognized in the analysis. This uncertainty is shown to result in significant limitations on the use of marginal cost comparisons even when point and nonpoint pollutants are perfect substitutes.

An economic analysis of agricultural nonpoint pollution control alternatives

Abstract: Hydrologic and economic models were used to analyze the costs and effectiveness of implementing best management practices under the Rural Clean Water Program in a southwestern Illinois watershed. Economic benefits and costs to water users and participating farmers were also evaluated. Results show that the cost-effectiveness of the implemented practices in achieving water quality could have been improved by promoting the adoption of conservation tillage and selected crop rotations on all cropland in the watershed.

Soil Conservation Practices and Water Quality: is Erosion Control the Answer?

Abstract: This paper is a computer simulation analysis of an agricultural nonpoint pollution problem. Computer modeling is a universally applicable tool that can be used for establishing the linkages between and the quality of agricultural runoff in both surface and subsurface flow. The tradeoffs between the costs of soil conservation practices and water quality are reported, and the economic implications of such tradeoffs are discussed. Soil and nutrient losses resulting from crop production practices are analyzed using a field-scale computer simulation model (CREAMS). No-till planting, reduced tillage, and sod waterway systems are more cost effective than other practices for controlling soil and nutrient runoff losses. Nitrate leaching losses are increased slightly by most soil conservation practices. Terrace systems and permanent vegetative cover impose the greatest societal cost for water quality protection. Public cost sharing and tax incentives encourage farmers to adopt expensive structural practices, and policies are needed to get cost-effective practices implemented on critical acreage. Extensive treatment of land is necessary for agricultural best management practices (BMPs) to significantly improve water quality in areas that are intensively farmed.

Reduced-input agriculture reduces nonpoint pollution

Abstract: RENEWED interest in using legumes to provide nitrogen for cash crops is just one of many indications that the stress of nonpoint pollution on regional and global life-support systems is bringing about a major change, almost an about-face, in the philosophy and technology of management-not just for agricultural systems but all production systems. Contamination of surface and groundwater by agricultural chemicals, soil erosion from both urban and rural landscapes, increases in greenhouse gases, and acid rain from power plants currently pose the greatest threats to the earth's life-supporting atmosphere, soil, and water bodies. Such nonpoint pollution sources, unlike point sources, cannot be controlled from the output side of a production system; they can only be controlled from the input side by what I call input management. The attention of agronomists and other production managers has for many years focused on increasing outputs, such as yields. Spectacular increases in yields of cash crops have been obtained partly by selection of high-yielding cultivars, but mostly by vast increases in the inputs of machine energy, fertilizers, and pesticides. For example, SO-year trends in Georgia agriculture were recently plotted as part of a study of changing …

Contributions of Rainfall to Constituent Loads in Storm Runoff from Urban Catchments

Abstract: Rainfall is a significant source of some constituents, particularly nitrogen species, in storm runoff from urban catchments. Median contributions of rainfall to storm runoff loads of 12 constituents from 31 urban catchments, representing eight geographic locations within the United States, ranged from 2 percent for suspended solids to 74 percent for total nitrite plus nitrate nitrogen. The median contribution of total nitrogen in rainfall to runoff loads was 41 percent. Median contributions of total-recoverable lead in rainfall to runoff loads varied by as much as an order of magnitude between catchments in the same geographic location. This indicates that average estimates of rainfall contributions to constituent loading in storm runoff may not be suitable in studies requiring accurate constituent mass-balance computations.

A Retrospective Pollution History of Southern California

Abstract: Time series of point and nonpoint source contaminant loading histories and pollution indicator variables were developed for southern California. These included: gross indicators (e.g., population, employment), habitat modifications (e.g., dredging, kelp bed size), nutrient loadings (e.g., N, P, TOC, TSS), and toxicant loadings (e.g., pesticides, PCBs, heavy metals). The reconstruction shows that the majority of contaminant loadings in southern California originate in Los Angeles and Orange counties but that San Diego County is rapidly becoming more prominent in toxic additions to the Southern California Bight. DDT, chlordane, PCBs, lead, and copper are of major interest in terms of the magnitudes of historical loadings to the Bight. Time series development revealed that emissions from the breakdown of products containing heavy metals and from the combustion of fossil fuels is the major source of heavy metals to the Bight. The primary source of nutrients, DDT, and PCBs to the Bight are sewage and industrial outfalls.

Agricultural Pollution Control: Implications from the Rural Clean Water Program

Abstract: The Rural Clean Water Program has provided a unique opportunity to study the economics of agricultural nonpoint source pollution control. Several implications for improving the economic efficiency of future agricultural nonpoint source pollution control programs can be drawn from the results. First, individual projects should be targeted towards water bodies that have water quality problems causing economic damages. Considerable variation can exist among areas in the magnitude of economic damages, which may not be proportional to physical impacts. Second, the relative costs and effectiveness of the practices selected to reduce the delivery of pollutants can vary dramatically from one location to another. Early identification and emphasis on cost-effective BMPs can substantially reduce project costs and may make a project economically justifiable that would not otherwise be so. Finally, some projects that do not hive potential economic benefits from water quality improvements exceeding government cost may have on-farm benefits from reduced costs and increased long-term yields that are sufficient to make total benefits (water quality and on-farm) exceed costs.

Evaluation of Management Practices to Control Agricultural Pollutants

Abstract: The objective of this study was to evaluate the effectiveness of various land-use practices upon the production of nonpoint source pollutants from small agricultural watersheds in Northern Virginia. Pollutant production at each watershed was determined by individual monitoring stations. Data analysis consisted of a determination of the site specific pollutant yield for similar watersheds subjected to differing crop management approaches. These collected data were then compared to those generated by a parametric, event model developed for this investigation. This synthetic data base was used to eliminate or reduce errors resulting from monitoring site differences and to extend the collected data for additional comparisons.

Prospects for Wetlands Use in Stormwater Management

Abstract: It is well established that wetlands under certain circumstances improve water quality. There is a limited literature on the long-term effects of using freshwater wetlands for stormwater storage and nonpoint pollution control. Much of this literature pertains to the use of wetlands for sewage effluent treatment. Some work has been done utilizing natural or artificial wetlands for flood control and/or water quality management. Water quality improvements from these studies show promise, but their direct application to the Pacific Northwest is limited. Some researchers believe the characteristics of wastewater and urban runoff are similar enough that some findings in the wastewater literature may be analogous to stormwater systems. These findings can be confirmed by careful studies in the Northwest to help fill the gaps in present knowledge. This paper summarizes wetlands water quality improvement principles from the literature, and areas of greatest uncertainty regarding the use of wetlands for urban stormwater management.

Implementation strategies for agricultural and silvicultural nonpoint source pollution control in california and wisconsin

Abstract: In the absence of detailed outlines such as those characteristic of the National Pollution Discharge Elimination System permit program, Nonpoint source pollution control is being initiated in a variety of ways in different states. In California, Regional Water Quality Control Boards play a strong enforcement role in point source control, but agricultural Nonpoint source needs are still being evaluated. Tentative approval of State Board of Forestry Forest Practice Rules by the State Water Resources Control Board has the potential of bringing Nonpoint control to all State and private forestry operations in the state. Wisconsin had developed an agricultural Nonpoint control program which emphasizes a state-wide policy of selecting priority watersheds under the administration of the state Department of Natural Resources, and developing implementation programs under the guidance of local county Land Conservation Committees. The Priority Watershed program institutes BMP's with cost-share funds authorized by the legislature. Wisconsin had not seen a problem in silvicultural activities, and has developed no statewide control program in that area. Common to effective land use control in both states is a state-level policy implemented by agencies within the state. This pattern may be the model for successful programs as development of areawide management strategies continue.

A Computational Method to Conduct Nonpoint Source Pollution Studies

Abstract: IN this article, we introduced and tested a computational method for estimating annual loads of sediment and phosphorus for nonpoint source pollution studies. The computational method was based on the development of relationships for simulating mean daily water discharges and mean daily concentrations of suspended sediment, total phosphorus, and dissolved phosphorus at the outlet of an agricultural watershed. Application of this computational method to a small Ontario agricultural watershed led us to estimate that 276 t of sediment, 436 kg of total phosphorus, and 139 kg of dissolved phosphorus emanated from cropland runoff (68.5 percent of the sediment and phosphorus loadings from agricultural activities) for the 1983 study period.

Analysis of agricultural nonpoint pollution control options in the st. albans bay watershed

Abstract: This report used a computer model, the Agricultural Nonpoint Source Pollution Model (AGNPS), to estimate nutrient losses both within the watershed at the field scale and at the watershed outlet. The capability of AGNPS to evaluate problem sites within a watershed can assist nonpoint pollution program administrators in targeting best management practices (BMP's). We concluded that substantial water quality improvements are possible from barnyard runoff control, animal waste storage structures, and timely nutrient applications.