SIMULATION AND DECISIONMAKING: THE PLATTE RIVER BASIN IN NEBRASKA1

Substantial conflict exists over water management and allocation in the Platte River Basin of Nebraska. An interdisciplinary computer simulation model, representing the water quantity, water quality, environmental, and economic dimensions of the conflict, was developed in order to analyze the tradeoffs among allocation scenarios. Most importantly, decisionmakers and interest groups were involved in model development. Simulation results for a base case and two scenarios are presented. One scenario favors protection of instream flow for wildlife; the other favors water diversions for agriculture. Impacts of the instream flow scenario, as measured by the amount of land irrigated, groundwater levels, the amount of wildlife habitat for cranes and catfish, and net agricultural benefits did not differ greatly from those of the base case. However, impacts of the diversion scenario were substantial. On the negative side, instream flows and wildlife habitat declined an average of 39 percent; while, on the positive side, groundwater levels and net agricultural benefits each increased 6 percent. The modeling process was successful insofar as it promoted an understanding among the highly diverse interest groups of the systems nature of the Basin. One agreement on a water diversion schedule among three of the parties has been reached, partly as a result of this process. More comprehensive compromises have not yet been forged. Our experience, however, indicates that modeling success at the policymaking level depends more on the extent to which the policymakers understand the model than it does on model sophistication.     

Regional multiresource models in a national framework

The design and integration of models projecting the effects of management on environmental systems is one step in the environmental planning process. Interactions between resources produced on the same unit of land under current and future management can be examined only when assumptions and processes of these dynamic environmental systems are quantified. Multiresource interaction models have generally been large and cumbersome while also suffering from an inadequate amount of detail. This article presents a conceptual framework for integrating individual resource models to project multiresource interactions at a regional scale. Land management impact projections require common definitions of the total land base and common definitions of management activities applied to the same land unit. A case example focusing on the resources of timber, forage, wildlife, fish, and water for the southern United States is presented.     

Low intervention soil remediation approaches

Traditional bioremediation approaches have been used to treat petroleum source contamination in readily accessible soils and sludges. Contamination under existing structures is a greater challenge. Options to deal with this problem have usually been in the extreme (i.e., to dismantle the facility and excavate to an acceptable regulated residual, or to pump and treat for an inordinately long period of time). The excavated material must be further remediated and cleanfill must be added to close the excavation. If site assessments were too conservative or incomplete, new contamination adulterating fill soils may result in additional excavation at some later date. Innovative, cost-efficient technologies must be developed to remove preexisting wastes under structures and to reduce future remediation episodes. An innovative soil bioremediation treatment method was developed and evaluated in petroleum hydrocarbon contaminated (PHC) soils at compressor stations of a natural gas pipeline running through Louisiana. The in-situ protocol was developed for remediating significant acreage subjected to contamination by petroleum-based lubricants and other PHC products resulting from a chronic leakage of lubricating oil used to maintain the pipeline itself. Initial total petroleum hydrocarbon (TPH) measurements revealed values of up to 12,000 mg/kg soil dry weight. The aim of the remediation project was to reduce TPH concentration in the contaminated soils to a level of <200 mg/kg soil dry weight, a level negotiated to be acceptable to state and federal regulators. After monitoring the system for 122 days, all sites showed greater than 99-percent reduction in TPH concentration.     

MAKING SMARTER ENVIRONMENTAL MANAGEMENT DECISIONS1

ABSTRACT: This paper outlines a sound, practical approach for making more informed decisions about environmental policy choices. It emphasizes the importance of using a structured decision process to specify and organize values, use these values to create alternatives, and assess tradeoffs to help achieve a desired balance across key objectives. Although these decision making steps are based on common sense, they are often neglected or poorly carried out as part of the complex evaluations of natural resource options. We discuss several reasons for this frequent neglect of decision making principles and provide examples from recent water use planning projects to demonstrate some of the benefits of using a structured, decision focused approach: new and better solutions, increased and more productive participation by stakeholders, and greater defensibility and acceptance of the resource management evaluation process and its conclusions.     

In-situ bioremediation of amine- and glycol-contaminated soils using low-intervention methods

Biological plugs are an innovative, low-intervention, in-situ bioremediation methodology for both saturated and unsaturated contaminated soils. They are modular in-ground immobilized microbe bioreactors designed to rapidly increase the oxidation of organic contaminants by placing an adapted consortia of microorganisms in close proximity to the contaminants of concern. The approach is versatile, in that contaminants can be remediated in-situ without the removal of existing structures as well as being able to efficiently and economically treat contaminants over a large area. Amine- and glycol-contaminated soils at gas sweetening plants, represent a significant problem in magnitude, prevalence, and risk along pipelines stretching through Canada's western provinces. A field pilot study was conducted at an isolated former gas sweetening plant in northwestern Alberta. Monoethyamine (MEA) and several glycols were successfully remediated in situ in a 138-day time frame. Soil toxicity was significantly reduced. The engineering challenges and associated economics of remediating such isolated sites are also presented.     

Diuron occurrence and distribution in soil and surface and ground water associated with grass seed production

Little is known about the occurrence and distribution of the herbicide diuron [3-(3,4-dichlorophenyl)-1,1-dimethyl urea] in soil, ground water, and surface water in areas affected by grass-seed production. A field study was designed to investigate the occurrence and distribution of diuron and its transformation products at a poorly drained field site located along an intermittent tributary of Lake Creek in the southern Willamette Valley of Oregon. The experimental sites consisted of a field under commercial grass seed production with a cultivated riparian zone and a second site that was part of the same grass seed field but with a noncultivated riparian zone. Diuron and its transformation product DCPMU [3-(3,4-dichlorophenyl)-1-methylurea] were the only significant residues detected in this study. Concentrations of diuron in surface water declined from a maximum of 28 microg/L immediately following application to low levels that persisted as long as flow was present. Diuron and DCPMU concentrations in shallow ground water (15-36 cm below ground surface) were highest (2-13 microg/L) in the zone immediately adjacent (0.5 m) to Lake Creek and indicated the influence of stream water on shallow ground water near the stream. Diuron and DCPMU detected in soil prior to the second season's application indicated the persistence of diuron and DCPMU from the previous year's application. Surface runoff during the rainy season removes only a very small percentage (<1%) of the applied herbicide. In addition, no evidence was obtained for the downward transport of diuron or its transformation products to deep ground water.     

Comparative Influence of Forest Management and Habitat Structural Factors on the Abundances of Hollow-Nesting Bird Species in Subtropical Australian Eucalypt Forest

We examined the impact of single-tree selective logging and fuel reduction burns on the abundance of hollow-nesting bird species at a regional scale in southeastern Queensland, Australia. Data were collected on species abundance and habitat structure of dry sclerophyll production forest at 36 sites with known logging and fire histories. Sixteen bird species were recorded with most being resident, territorial, obligate hollow nesters that used hollows that were either small (<10 cm diameter) or very large (>18 cm diameter). Species densities were typically low, but combinations of two forest management and three habitat structural variables influenced the abundances of eight bird species in different and sometimes conflicting ways. The results suggest that habitat tree management for biodiversity in production forests cannot depend upon habitat structural characteristics alone. Management histories appear to have independent influence (on some bird species) that are distinguishable from their impacts on habitat structure per se. Rather than managing to maximize species abundances to maintain biodiversity, we may be better off managing to avoid extinctions of populations by identifying thresholds of acceptable fluctuations in populations of not only hollow-nesting birds but other forest dependent wildlife relative to scientifically valid forest management and habitat structural surrogates.