Members of Langhei Ecology have led and made substantial contributions to several large-scale ecological risk assessments. These assessments have been conducted at levels of organization in the biological hierarchy ranging from populations to landscapes. The assessments have included physical, chemical, and biological stressors in single- and multiple-stressor analyses, over geographic scales ranging from individual water bodies to the entire United States east of the Mississippi. Most of the assessments have explicitly considered both the probability and magnitude of ecological effects as a function of the magnitude of stress or alternative management actions.

Risk-based Review of a Hydropower License Application in the Penobscot River Basin

Under Versar's FERC-OHL¹ support subcontract with Stone and Webster Environmental Services, the likelihood of successful restoration of the Penobscot River stock of Atlantic salmon was examined under existing conditions, with the addition of a new dam in the lower part of the basin, with upgrades and expansions at selected existing facilities, and under various mitigation scenarios. Quantitative estimates of the likelihood of successful restoration were made using the U.S. Fish and Wildlife Service's ASAL Atlantic salmon population model (Rago and Goodyear 1985). The project critically reviewed the ASAL work conducted by a working group comprising the U.S. Fish and Wildlife Service, the Atlantic Salmon Restoration Scientific Committee, the Penobscot Indian Nation, and the applicant, as well as ASAL work conducted independently by the applicant. New analyses were also conducted to examine the significance of uncertainties in model parameters and the relative effectiveness of alternative mitigation scenarios. The basin-scale assessment used a risk-reduction framework to evaluate the development proposal and alternative mitigation measures, including trap and truck, dam decommissioning, dam removal, long-term stocking, and harvest restrictions. The ASAL model was used to project the expected run sizes over the license term and the likelihood of full utilization of nursery habitat in each of several river segments within the Penobscot basin. Spreadsheet models were also constructed and used to estimate the relative, basin-wide benefits to salmon restoration accruing from alternative dam removals and decommissioning. The analyses and associated risk characterizations were central to the Environmental Impact Statement prepared in compliance with NEPA requirements.

This project is also described under the following project categories:
Hydropower and Fisheries
Population Modeling and Stock Assessment

¹ The Federal Energy Regulatory Commission (FERC) Office of Hydropower Licensing (OHL) is responsible for regulating non-federal hydropower development consistent with applicable laws and Commission regulations, and ensuring that environmental and other concerns are adequately addressed before any Commission action.

Grass Carp and Submerged Aquatic Vegetation in the Potomac River

Under a Versar prime contract with the U.S. Environmental Protection Agency, Office of Research and Development, an assessment was made of the likelihood of adverse effects on submersed aquatic vegetation (SAV) in the Potomac river from stocking of triploid-certified grass carp into impoundments within the basin. The assessment considered an intensive stocking scenario, and propagated the uncertainties associated with U.S. Fish and Wildlife Service certification of grass carp for diploid (non-sterile) status, escape from impoundments, and reproductive success in the Potomac River. The risk model generated probability distributions for grass carp abundance. The potential for adverse effects on SAV was then evaluated using a temperature- and sized-based model of SAV consumption by grass carp. A major conclusion of the project was that use of triploid-certified fish was not sufficient to ensure a low probability of establishing a naturally reproducing population of grass carp in the Potomac River. Depending on such factors as stocking rate, escape rate, and reproductive success of diploid fish, grass carp could be expected to become established in the river in the near term and eventually reach population densities high enough to consume a quantity of SAV in excess of annual SAV production.

This project is also described under the following project category:
Population Modeling and Stock Assessment

Risk Assessment for a Proposed Introduction of Pacific Salmon to a Tributary of the Delaware River

Under a prime contract held by Versar, Inc., a Draft Environmental Impact Statement (DEIS) was prepared for a proposed experimental stocking of Pacific salmon in a tributary of the Delaware River. In support of the DEIS, a probabilistic model was developed and used to estimate the abundance and dispersion of adult salmon returning from the ocean to spawn in fresh water. The model included the magnitude and duration of stocking, life history characteristics, and uncertainty in return rates, harvest rates, and straying behavior. Probabilistic models were developed for chinook salmon, coho salmon, and steelhead trout. Information provided by the risk assessment was cited by the project proponent as a major factor in the decision to withdraw the proposal.

This project is also described under the following project category:
Population Modeling and Stock Assessment

Ecological Risk Assessment for the Middle Platte River Floodplain

Under the Cadmus Group's prime contract with the U.S. Environmental Protection Agency, Office of Water, Health and Ecological Criteria Division, technical support was provided for an ecological risk assessment for the middle Platte River floodplain in central Nebraska. This case study was one of several across the United States sponsored by the Office of Water and Risk Assessment Forum to support the development of Agency-wide guidance for ecological risk assessment. This complex, landscape-scale assessment comprised multiple aquatic and terrestrial habitat types, multiple levels of biological organization, and multiple, interacting stressors affecting a diverse array of biota including wetland plant communities, fish, amphibians, invertebrates, and birds. An important stressor on this system is alteration of the hydrologic regime by water development projects. The assessment involved tradeoffs, not only between development and non-development values, but also tradeoffs between competing non-development (i.e. ecological) values. The early phases of this project centered on helping the project team use stakeholder input and local expertise to formulate management goals and objectives and identify appropriate assessment endpoints. Later phases included finalization and implementation of the analysis plan.

This project is also described under the following project category:
Population Modeling and Stock Assessment

Colloquium on Issues in Ecological Risk Assessment

As a consultant to Eastern Research Group, a member of Langhei Ecology served as a panelist and peer reviewer for a colloquium sponsored by the U.S. EPA Risk Assessment Forum and Office of Water. Watershed-scale ecological risk assessment case studies under development were critically reviewed and written comments were delivered in advance of the colloquium. At the colloquium, additional comments were offered during presentations and discussions on the developing case studies. The case studies were in an early stage of development at that time, and comments and discussion focused on ecological and analytical issues relating to planning of the risk assessments.

Watershed-Level Aquatic Ecosystem Protection: Value Added by the Ecological Risk Assessment Approach

This study, conducted under a contract to the Cadmus Group, Inc. was sponsored by the Water Environment Research Foundation (WERF) to promote integration of federal, state, and local risk-based, watershed approaches to protecting aquatic ecosystems. The project evaluated the opportunities for and obstacles to integrating ecological risk assessment into a watershed approach to managing aquatic resources. The report also evaluated the value added by incorporating risk assessment into watershed-scale management strategies.

Nitrogen Loading and Restoration of Sea Grasses in Waquoit Bay, Massachusetts

Restoration of sea grass beds is a major management objective driving the USEPA's ecological risk assessment case study in Waquoit Bay, Massachusetts. Nitrogen loading from septic tanks and other sources in the watershed is thought to be a major factor in the decline of sea grasses in the bay. Under a prime contract with EPA's Office of Science and Technology held by the Cadmus Group, existing models of nitrogen loading to Waquoit Bay were evaluated for use in the ongoing watershed-scale ecological risk assessment. Each of the existing models was found lacking, so a new modeling approach was developed, combining the desirable attributes of the existing models, to evaluate the relationship between nitrogen sources and changes in the extent of sea grass meadows in the bay. The site-specific, mechanistic modeling approach takes into account the time lag between changes in land use and nitrogen loading to the bay, and complements cross-sectional, empirical models that are based on data from many similar bays but do not take the time lags into account. EPA subsequently adopted the proposed modeling approach and funded development of the new models in support of the risk assessment.

Regional-Scale Assessment of the Vulnerability of the Eastern U.S. to Acid Deposition

While employed by the National Wildlife Federation, a member of Langhei Ecology conducted an assessment of the geographic scope and degree of vulnerability of the eastern United States to acid deposition based on patterns and intensity of deposition and local geology. Areas east of the Mississippi at high, medium, and low risk of acidification were delineated by overlaying data for exposure and sensitivity. This research was entered into the Congressional Record during hearings on acid rain control bills in the 97th Congress.

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