Nonpoint source pollution risk assessment in a watershed context

Nonpoint source pollution control requires assessment of the influence of dispersed runoff-contributing areas on downstream water quality. This evaluation must consider two separate phases: site-to-stream loading and downstream fluvial transport. Any model, combination of models, or procedure for making this assessment can be generalized to a simple spatial model or framework, which considers runoff or pollutant loading per unit area and down-stream attenuation, with drainage area as a scaling factor. This spatial model has a probabilistic interpretation and can be used in conjunction with a standard dilution model to give a probabilistic estimate of the impacts at the basin mouth of runoff from a specific upstream contributing area. It is illustrated by applying it to an assessment of the probability that various copper concentrations at the mouth of the urbanized South Platte River basin in Denver, Colorado, USA, will be exceeded as a result of runoff from a subbasin within the city. Determining the probability that a concentration of a pollutant at the basin mouth can be attributed to runoff from a discrete area within the basin is useful for targeting and risk assessment because it enables quantitative risk-based comparisons. The spatial framework is also useful for evaluating management and control options, since actions within the basin can be directly linked to water quality at a downstream point.     

RED ALDER LEAF LITTER AND STREAMWATER QUALITY IN WESTERN OREGON1

ABSTRACT: Streamside red alder (Alnus rubra Bong.) stands are common in western Oregon, and they have been suspected of causing water quality problems in domestic supplies during autumn leaf fall. Studies in the Seaside municipal watershed showed potential water quality effects (particularly increased color) from alder leaves, but stream sampling during 1981–82 revealed no chronic problems. The few observed short-term increases in water color occurred near the onset of storm flows, which suggested a flushing of organic matter storage sites. An extended period of unusually low flows and high leaf fall are probably necessary to produce significant water quality problems in this stream system. Laboratory leaching of alder leaves in filtered stream water indicated a fairly constant release of colored organic matter over time, and running water leached this matter more efficiently than still water. Water color increased linearly with increasing leaf mass added to still water, and for a given leaf mass there appeared to be a limit to the amount of colored matter that could be removed in the first 48 hours of leaching. Other laboratory tests showed that ultraviolet absorbance (254 mm) may provide a reasonable estimate of dissolved organic carbon concentrations in systems dominated by alder leaf inputs.     

Community and individual reaction to environmental hazards: Developing a measurement technology

This study was an attempt to develop an efficient method of monitoring and assessing how members of a community react to a toxic hazard in their community. The intent was to develop a short instrument which could be applied in multiple settings, or in the same setting several times. The methodology was a short questionnaire that addressed six issues: sources of information about the hazard, beliefs about justice and responsibility, beliefs about why the hazard is a problem, extent of active concern, involvement in community affairs, and satisfaction with life. A mailed questionnaire was developed and tested in a community near an EPA Superfund site in the United States. Results of the effort are discussed relative to the particular community studied, and relative to furthering the assessment technology begun in this research.     

ESTIMATION OF DRAINAGE AREAS IN A HOMOGENEOUS LANDSCAPE1

In areas where there is little or no topographic relief and where soils, vegetation, geologic structure and other factors are essentially uniform, identification of drainage basin boundaries is difficult or impossible. In such a homogeneous landscape, however, assumptions may be made that the hydrologic and geomorphic controls over drainage basin development are constant within the area. If this is true, it is suggested, the drainage area of a stream is related solely to the stream length and factors governing the length-area relationship are also constant. A simple formula based on these assumptions and the gravity model is proposed which can be used to estimate drainage divides in a homogeneous landscape.     

Environmental health implications of global climate change

This paper reviews the background that has led to the now almost-universally held opinion in the scientific community that global climate change is occurring and is inescapably linked with anthropogenic activity. The potential implications to human health are considerable and very diverse. These include, for example, the increased direct impacts of heat and of rises in sea level, exacerbated air and water-borne harmful agents, and--associated with all the preceding--the emergence of environmental refugees. Vector-borne diseases, in particular those associated with blood-sucking arthropods such as mosquitoes, may be significantly impacted, including redistribution of some of those diseases to areas not previously affected. Responses to possible impending environmental and public health crises must involve political and socio-economic considerations, adding even greater complexity to what is already a difficult challenge. In some areas, adjustments to national and international public health practices and policies may be effective, at least in the short and medium terms. But in others, more drastic measures will be required. Environmental monitoring, in its widest sense, will play a significant role in the future management of the problem.     

The pattern of cadmium in the environment of five Minnesota cities

This paper reports on the cadmium results of a soil survey conducted by the State of Minnesota during the summer of 1986. The survey collected soil-dust trom the oldest census tracts of Minneapolis, St. Paul, Duluth, St. Cloud and Rochester. The results reveal fundamental differences in soil cadmium among cities. Soil cadmium exceeds 2 g g^–1 in 8.4% of the samples in Minneapolis, and 7.0, 4.0, 3.3 and 1.5% respectively of the samples collected in St. Paul, Duluth, St. Cloud and Rochester. Minneapolis and St. Paul residential houseside soil samples had cadmium levels that exceeded 2 g g^–1 in 24.5 and 21.2% respectively of the samples collected. By comparison, the Minneapolis and St. Paul residential streetside soil samples had cadmium levels that exceeded 2 g g^–1 in 1.2 and 0.6%, respectively, of the samples collected. Also the Minneapolis and St. Paul residential midyard soil samples had cadmium levels that exceeded 2 g g^–1 in 1.9 and 5.5%, respectively, of the samples collected. Cadmium levels for the combined data for all cities and communities in Minneapolis appears to be directly related to traffic flow. However, cadmium levels around housesides and in midyards do not follow patterns of traffic flow in the same manner as cadmium content of soils along streetsides. St. Paul has an anomalously high cadmium content toward the east of the city compared with the west side of the city. The Pigs Eye sewage sludge incinerator located east of the city is the most likely source of cadmium to cause this pattern. This study provides essential urban background information about both the fundamental environmental patterns of cadmium as well as processes which appear to operate to cause those patterns.     

A decade of recreation ratings for six silviculture treatments in Western Oregon

Managed forests are increasingly being used for recreation. As a result, foresters may be expected to tailor silvicultural treatments to accommodate specific recreation preferences. To better understand changes in hiking and camping quality in the years following a harvest, six sites on the Oregon State University's research forest were evaluated annually for 11 years. Multiple comparison and regression analyses were used to describe the data. Results show that recreation ratings generally improved over time; recreation ratings were related to but different from scenic ratings; and there were differences among recreation activities. Although several studies have previously examined recreation quality after harvest, we know of no other study that has tracked the ratings of individual harvest units through the early stages of stand regeneration.     

USE OF THE DELPHI METHOD IN RESOLVING COMPLEX WATER RESOURCES ISSUES1

ABSTRACT: The tri‐state river basins, shared by Georgia, Alabama, and Florida, are being modeled by the U.S. Fish and Wildlife Service and the U.S. Army Corps of Engineers to help facilitate agreement in an acrimonious water dispute among these different state governments. Modeling of such basin reservoir operations requires parallel understanding of several river system components: hydropower production, flood control, municipal and industrial water use, navigation, and reservoir fisheries requirements. The Delphi method, using repetitive surveying of experts, was applied to determine fisheries' water and lake‐level requirements on 25 reservoirs in these interstate basins. The Delphi technique allowed the needs and requirements of fish populations to be brought into the modeling effort on equal footing with other water supply and demand components. When the subject matter is concisely defined and limited, this technique can rapidly assess expert opinion on any natural resource issue, and even move expert opinion toward greater agreement.     

MARSH DEVELOPMENT AT RESTORATION SITES ON THE WHITE MOUNTAIN APACHE RESERVATION,ARIZONA1

ABSTRACT: To prioritize sites for riparian restoration, resource managers need to understand how recovery processes vary within landscapes. Complex relationships between watershed conditions and riparian development make it difficult to predict the outcomes of restoration treatments in the semiarid Southwest. Large floods in 1993 scoured riparian areas in the Carrizo watershed on the White Mountain Apache Reservation in east‐central Arizona. We evaluated recovery at three of these sites using repeated photographs and measurements of channel cross sections and stream‐side vegetation along permanent transects. The sites were mapped as lying on the same soil type, had similar streamside vegetative communities, and were similarly treated through livestock exclusion and supplemental seeding. However, the sites and individual reaches within the sites followed strikingly different development paths. Dramatic recovery occurred at a perennial reach where cover of emergent wetland plants increased from 4.7 percent (standard error = 0.8 percent) in October 1995 to 55.5 percent (standard error = 2.7 percent) in September 2001. At several other reaches, geologic and hydro geomorphic characteristics of the sites limited inputs of fine sediment or surface water, resulting in modest or negligible increases in emergent cover. Recovery efforts for highly valued marshlands in this region should prioritize perennial reaches in low gradient valleys where salty sediments are abundant.     

The legacy of lead pollution: (dis)trust in science and the debate over Superfund

Lead contamination is a significant health hazard in communities around the world, but this environmental toxin often remains unknown to residents living near hazardous sites. This research investigates a unique case where residents were informed of lead contamination but rejected official and scientific narratives regarding environmental risks. The case study involves a decommissioned smelter in Colorado. Drawing from data collected over three years, the researchers examine how officials and experts communicated the severity of environmental health hazards. Despite these efforts, residents opposed the Environmental Protection Agency’s attempts to place the site on the National Priorities List for federal cleanup. The government’s framing of science and environmental risk failed to resonate with homeowners, despite the known and significant scientific evidence confirming environmental health hazards, and residents’ perceptions of lead contamination were mitigated by material concerns, including property values and community stigma. Implications for future research on lead contamination, environmental risk, and trust in science are discussed.