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At least 325 records · Page 18Linked to original sources

Navigating uncertainty and competing objectives: Spring chinook salmon recovery in the upper Willamette river

Globally, anadromous fish populations are threatened with extinction due to multiple factors, including river impoundments that block migration, widespread alteration of physical habitat, temperature, and flow regimes, commercial and recreational harvest, changes in biological communities, and long-term climate trends. In this synthesis, we describe how physical and biological factors, policy and law, and public resource allocation affect management of spring-run Chinook Salmon ( Oncorhynchus tshawytscha ) in the Upper Willamette River (UWR), Oregon, USA. Efforts to restore salmon populations often involve trade-offs, for example, water management decisions must account for flood control, agricultural and municipal water use, and management of other species. UWR Chinook Salmon recovery efforts are also governed by multiple laws, policies, and action agencies that in some cases have incongruent objectives. Competing and conflicting objectives, combined with uncertainty regarding the outcomes of proposed management actions, create significant challenges for decision makers. Resource limitations, regulatory constraints, and incongruent objectives have created challenges for managers in the UWR, but opportunities exist for improved adaptive management and collaboration, which could build trust and engagement among stakeholders and ultimately support the successful implementation of decision tools. A suite of decision support tools that have been used in the Willamette River basin and elsewhere across the range of Pacific salmon have the potential to enhance decision processes. These tools can be effective when decision makers and stakeholders commit to long-term, collaborative utilization of the tools for decision making, and when available resources and regulatory environments are conducive to implementation and adaptive refinement of both the decision-support tools and management plans. The general biological and institutional principles discussed for UWR Chinook Salmon in this work apply more generally to populations of anadromous fishes across their range, especially to populations in highly regulated river systems.

Oregon↗

Unintended consequences of biofuels production?The effects of large-scale crop conversion on water quality and quantity

In the search for renewable fuel alternatives, biofuels have gained strong political momentum. In the last decade, extensive mandates, policies, and subsidies have been adopted to foster the development of a biofuels industry in the United States. The Biofuels Initiative in the Mississippi Delta resulted in a 47-percent decrease in cotton acreage with a concurrent 288-percent increase in corn acreage in 2007. Because corn uses 80 percent more water for irrigation than cotton, and more nitrogen fertilizer is recommended for corn cultivation than for cotton, this widespread shift in crop type has implications for water quantity and water quality in the Delta. Increased water use for corn is accelerating water-level declines in the Mississippi River Valley alluvial aquifer at a time when conservation is being encouraged because of concerns about sustainability of the groundwater resource. Results from a mathematical model calibrated to existing conditions in the Delta indicate that increased fertilizer application on corn also likely will increase the extent of nitrate-nitrogen movement into the alluvial aquifer. Preliminary estimates based on surface-water modeling results indicate that higher application rates of nitrogen increase the nitrogen exported from the Yazoo River Basin to the Mississippi River by about 7 percent. Thus, the shift from cotton to corn may further contribute to hypoxic (low dissolved oxygen) conditions in the Gulf of Mexico.

Open-File Report↗

Introduction to special section on impacts of land use change on water resources

Changes in land use have potentially large impacts on water resources, yet quantifying these impacts remains among the more challenging problems in hydrology. Water, food, energy, and climate are linked through complex webs of direct and indirect effects and feedbacks. Land use is undergoing major changes due not only to pressures for more efficient food, feed, and fiber production to support growing populations but also due to policy shifts that are creating markets for biofuel and agricultural carbon sequestration. Hydrologic systems embody flows of water, solutes, sediments, and energy that vary even in the absence of human activity. Understanding land use impacts thus necessitates integrated scientific approaches. Field measurements, remote sensing, and modeling studies are shedding new light on the modes and mechanisms by which land use changes impact water resources. Such studies can help deconflate the interconnected influences of human actions and natural variations on the quantity and quality of soil water, surface water, and groundwater, past, present, and future.

Water Resources Research↗

Sustaining Rocky Mountain landscapes: Science, policy and management for the Crown of the Continent ecosystem

Prato and Fagre offer the first systematic, multi-disciplinary assessment of the challenges involved in managing the Crown of the Continent Ecosystem ( CCE), an area of the Rocky Mountains that includes northwestern Montana, southwestern Alberta, and southeastern British Columbia. The spectacular landscapes, extensive recreational options, and broad employment opportunities of the CCE have made it one of the fastest growing regions in the United States and Canada, and have lead to a shift in its economic base from extractive resource industries to service-oriented recreation and tourism industries. In the process, however, the amenities and attributes that draw people to this “New West” are under threat. Pastoral scenes are disappearing as agricultural lands and other open spaces are converted to residential uses, biodiversity is endangered by the fragmentation of fish and wildlife habitats, and many areas are experiencing a decline in air and water quality. Sustaining Rocky Mountain Landscapes provides a scientific basis for communities to develop policies for managing the growth and economic transformation of the CCE without sacrificing the quality of life and environment for which the land is renowned. This forthcoming edited volume focuses on five aspects of sustaining mountain landscapes in the CCE and similar regions in the Rocky Mountains. The five aspects are: 1) how social, economic, demo graphic and environmental forces are transforming ecosystem structure and function, 2) trends in use and conditions for human and environmental resources, 3) activating science, policy and education to enhance sustainable landscape management, 4) challenges to sustainable management of public and private lands, and 5) future prospects for achieving sustainable landscapes.

Idaho, Montana↗

The Chesapeake Bay Land Change Model (CBLCM): Simulating future land use scenarios and potential impacts on water quality

The Chesapeake Bay Land Change Model (CBLCM) is an open-source pseudo-cellular automata land change model tailored for loose coupling with watershed models. The CBLCM simulates infill development, residential and commercial development, natural land and agricultural land conversion, and growth served by sewer or septic wastewater treatment. The CBLCM is unique among land change models by simulating multiple types of development and explicitly accounting for infill development and the spatial patterns of development densities. The CBLCM was used to simulate five future land use scenarios, holding population constant, for all counties within and adjacent to the Chesapeake Bay watershed from 2013 to 2055. Results are presented here for the state of Maryland over the period 2013–2025 to illustrate model functionality and validation. The growth management (GM) scenario achieved the least development and potential impacts to natural and agricultural lands while accommodating the same amount of population growth as the other four scenarios. Scenarios focusing exclusively on natural or agricultural land protection shifted development to unprotected areas resulting in unforeseen water quality consequences. Simultaneously achieving more compact development while protecting the most valued natural and agricultural lands requires a combination of GM and land conservation policies and actions.

Maryland↗

Excess nitrogen in the U.S. environment: Trends, risks, and solutions

It is not surprising that humans have profoundly altered the global nitrogen (N) cycle in an effort to feed 7 billion people, because nitrogen is an essential plant and animal nutrient. Food and energy production from agriculture, combined with industrial and energy sources, have more than doubled the amount of reactive nitrogen circulating annually on land. Humanity has disrupted the nitrogen cycle even more than the carbon (C) cycle. We present new research results showing widespread effects on ecosystems, biodiversity, human health, and climate, suggesting that in spite of decades of research quantifying the negative consequences of too much available nitrogen in the biosphere, solutions remain elusive. There have been important successes in reducing nitrogen emissions to the atmosphere and this has improved air quality. Effective solutions for reducing nitrogen losses from agriculture have also been identified, although political and economic impediments to their adoption remain. Here, we focus on the major sources of reactive nitrogen for the United States (U.S.), their impacts, and potential mitigation options. Sources: ??? Intensive development of agriculture, industry, and transportation has profoundly altered the U.S. nitrogen cycle. ??? Nitrogen emissions from the energy and transportation sectors are declining, but agricultural emissions are increasing. ??? Approximately half of all nitrogen applied to boost agricultural production escapes its intended use and is lost to the environment. Impacts: ??? Two-thirds of U.S. coastal systems are moderately to severely impaired due to nutrient loading; there are now approximately 300 hypoxic (low oxygen) zones along the U.S. coastline and the number is growing. One third of U.S. streams and two fifths of U.S. lakes are impaired by high nitrogen concentrations. ??? Air pollution continues to reduce biodiversity. A nation-wide assessment has documented losses of nitrogen-sensitive native species in favor of exotic, invasive species. ??? More than 1.5 million Americans drink well water contaminated with too much (or close to too much) nitrate (a regulated drinking water pollutant), potentially placing them at increased risk of birth defects and cancer. More research is needed to deepen understanding of these health risks. ??? Several pathogenic infections, including coral diseases, bird die-offs, fish diseases, and human diarrheal diseases and vector-borne infections are associated with nutrient losses from agriculture and from sewage entering ecosystems. ??? Nitrogen is intimately linked with the carbon cycle and has both warming and cooling effects on the climate. Mitigation Options: ??? Regulation of nitrogen oxide (NOX) emissions from energy and transportation sectors has greatly improved air quality, especially in the eastern U.S. Nitrogen oxide is expected to decline further as stronger regulations take effect, but ammonia remains mostly unregulated and is expected to increase unless better controls on ammonia emissions from livestock operations are implemented. ??? Nitrogen loss from farm and livestock operations can be reduced 30-50% using current practices and technologies and up to 70-90% with innovative applications of existing methods. Current U.S. agricultural policies and support systems, as well as declining investments in agricultural extension, impede the adoption of these practices. Society faces profound challenges to meet demands for food, fiber, and fuel while minimizing unintended environmental and human health impacts. While our ability to quantify transfers of nitrogen across land, water, and air has improved since the first publication of this series in 1997, an even bigger challenge remains: using the science for effective management policies that reduce climate change, improve water quality, and protect human and environmental health. ?? The Ecological Society of America.

Issues in Ecology↗

Chapter 8 Tool for monitoring hydrophilic contaminants in water: polar organic chemical integrative sampler (POCIS)

The development of the polar organic chemical integrative sampler (POCIS) provides environmental scientists and policy makers a tool for assessing the presence and potential impacts of the hydrophilic component of these organic contaminants. The POCIS provides a means for determining the time-weighted average (TWA) concentrations of targeted chemicals that can be used in risk assessments to determine the biological impact of hydrophilic organic compounds (HpOCs) on the health of the impacted ecosystem. Field studies have shown that the POCIS has advantages over traditional sampling methods in sequestering and concentrating ultra-trace to trace levels of chemicals over time resulting in increased method sensitivity, ability to detect chemicals with a relatively short residence time or variable concentrations in the water, and simplicity in use. POCIS extracts can be tested using bioassays and can be used in organism dosing experiments for determining toxicological significance of the complex mixture of chemicals sampled. The POCIS has been successfully used worldwide under various field conditions ranging from stagnant ponds to shallow creeks to major river systems in both fresh and brackish water.

Comprehensive Analytical Chemistry↗

Implementation of controlled floods for sediment management on the Colorado River in Grand Canyon under aridification

In addition to supplying water for agriculture, cities, and industry, the Colorado River traverses the Colorado Plateau, including several of the most unique and valued National Parks and Recreation Areas in the United States. Although the water needs of these landscapes were not considered at the time water allocations were first negotiated, these needs were recognized in subsequent legislation and policy. Management goals address a range of aquatic and riparian resources, including fine sediment (sand, silt, and clay) which, in Grand Canyon, is important for ecological, cultural, and recreational resources. Over ~30 years, stakeholders, resource managers, and scientists collectively developed operational strategies for sediment management to meet goals outlined by an adaptive management program. However, prolonged drought, or “aridification,” resulting in declining runoff and the lowest reservoir storage elevations in decades has challenged those strategies. The paradigm for sustainable sediment management relies on (1) sand accumulation on the bed of the Colorado River during periods of sediment-rich tributary floods from summer/fall thunderstorms, and (2) dam-released controlled (artificial) floods, referred to as High-Flow Experiments (HFEs), to redistribute the accumulated sand to rebuild eroded bar and floodplain deposits. The management protocol, which specifies narrowly defined sand accumulation periods and HFE implementation windows, is based on implementing HFEs in late fall during the period of greatest sediment enrichment, before higher winter releases for hydropower erode the accumulated sand from the riverbed. Low dam releases associated with drought, however, have changed the pattern of sand accumulation and low reservoir elevations have prevented HFE implementation in the defined window. An alternative strategy for HFE planning and implementation was tested opportunistically in April 2023 following lower-than-normal winter dam releases. We present findings from this HFE indicating that sand enrichment and sandbar building equaled or exceeded that of HFEs conducted under the established management protocol. These findings show that management goals for sediment under conditions of prolonged drought may be achievable but will likely require substantial changes in dam management strategies.

Arizona↗

Response to L. Land comment on Bricker, Rice, Bricker (2014) From Headwaters to Coast: Influence of human activities on water quality of the Potomac River Estuary. Aquatic Geochemistry 20: 291-324

Overabundance of nutrients is considered one of the top challenges to most populated coastal water bodies, including Chesapeake Bay (Executive Order 13508). As scientists, one of our responsibilities is to contribute to the discussion and evaluation of management actions that have the potential to decrease pollution with concomitant improvement of water quality. Results of our science should inform the legislative process for public policy. Bricker et al. (2014) consider the use of shellfish (i.e., oysters) to remediate nutrient pollution in the Potomac River Estuary (PRE), a tributary to Chesapeake Bay. This concept, termed bioextraction, has generated interest around the globe and has shown promise as a nutrient-removal method in other estuaries and with other shellfish species (Lindahl et al. 2005; Ferreira et al. 2009; Shumway 2011; Silva et al. 2011; Carmichael et al. 2012; Pollack et al. 2013; Rose et al. 2014).

Aquatic Geochemistry↗

Seventy questions of importance to the conservation of the North Central grasslands of the United States in a changing climate

Successful conservation of ecosystems in a changing climate requires actionable research that directly supports the rethinking and revising of management approaches to address changing risks and opportunities. As an important first step toward actionable research, we reviewed and synthesized grassland management-related documents to identify broadly shared questions that, if answered, would help to support collective conservation of the grasslands in the northern Great Plains of the United States in a changing climate. A Management Priorities Working Group reviewed 183 grassland-relevant management documents and identified 70 questions. Feedback was iteratively provided by a Climate and Ecology Working Group, an Advisory Committee, and representatives from grassland management agencies and organizations. The identified questions generally fall under 15 topics: land conversion; restoration; disturbance regimes; woody encroachment; herbaceous invasives; grazing; water quality, quantity, and availability; animal species; private land; public understanding; legal and policy changes; economic incentives; coordination across management entities; accessibility of science and tools; and novel ways of thinking. These questions can inform a research agenda for researchers looking to conduct actionable science in the Great Plains grassland ecosystems. Both the approach and the questions presented here can also be adapted and applied in other regions and ecosystems.

Colorado, Kansas, Montana, Nebraska, North Dakota,↗

Long-term reductions in anthropogenic nutrients link to improvements in Chesapeake Bay habitat

Great effort continues to focus on ecosystem restoration and reduction of nutrient inputs thought to be responsible, in part, for declines in estuary habitats worldwide. The ability of environmental policy to address restoration is limited, in part, by uncertainty in the relationships between costly restoration and benefits. Here, we present results from an 18-y field investigation (1990-2007) of submerged aquatic vegetation (SAV) community dynamics and water quality in the Potomac River, a major tributary of the Chesapeake Bay. River and anthropogenic discharges lower water clarity by introducing nutrients that stimulate phytoplankton and epiphyte growth as well as suspended sediments. Efforts to restore the Chesapeake Bay are often viewed as failing. Overall nutrient reduction and SAV restoration goals have not been met. In the Potomac River, however, reduced in situ nutrients, wastewater-treatment effluent nitrogen, and total suspended solids were significantly correlated to increased SAV abundance and diversity. Species composition and relative abundance also correlated with nutrient and water-quality conditions, indicating declining fitness of exotic species relative to native species during restoration. Our results suggest that environmental policies that reduce anthropogenic nutrient inputs do result in improved habitat quality, with increased diversity and native species abundances. The results also help elucidate why SAV cover has improved only in some areas of the Chesapeake Bay.

Chesapeake Bay↗

A policy evaluation tool: Management of a multiaquifer system using controlled stream recharge

A model for the optimal allocation of water resources was developed for a multiaquifer groundwater and surface water system near Livermore, California. The complex groundwater system was analyzed using a transient, quasi-three-dimensional model that considers the nonlinear behavior of the unconfined aquifer. The surface water system consists of a reservoir that discharges water to three streams which in turn recharge the upper aquifer. Nonlinear streamflow-recharge relationships were developed based upon synoptic field measurements of streamflow. The management model uses constrained optimization to minimize the cost of allocating surface water subject to physical and economic restrictions. Results indicate that a combined hydrologic and economic management model can be used to evaluate management practices of a complex hydrogeologic system. Questions can be posed which either would be impossible or extremely difficult to solve without the management model. We demonstrate the utility of such a model in three areas. First, the efficiency of intra-basin water allocations is evaluated. Second, critical factors that control management decisions of the basin are identified. Third, the influence of economic incentives that can best satisfy the conflicting objectives of various water users is explored.

Water Resources Research↗

Instream water use in the United States: water laws and methods for determining flow requirements

Water use generally is divided into two primary classes - offstream use and instream use. In offstream use, sometimes called out-of-stream or diversionary use, water is withdrawn (diverted) from a stream or aquifer and transported to the place of use. Examples are irrigated agriculture, municipal water supply, and industrial use. Each of these offstream uses, which decreases the volume of water available downstream from the point of diversion, is discussed in previous articles in this volume. Instream use, which generally does not diminish the flow downstream from its point of use, and its importance are described in this article. One of the earliest instream uses of water in the United States was to turn the water wheels that powered much of the Nation's industry in the 18th and 19th centuries. Although a small volume of water might have been diverted to a mill near streamside, that water usually was returned to the stream near the point of diversion and, thus, the flow was not diminished downstream from the mill. Over time, the generation of hydroelectric power replaced mill wheels as a means of converting water flow into energy. Since the 1920's, the generation of hydroelectric power increasingly has become a major instream use of water. By 1985, more than 3 billion acre-feet of water (3,050,000 million gallons per day) was used annually for hydropower generation (Solley and others, 1988, p. 45)-enough water to cover the State of Colorado to a depth of 51 feet. Navigation is another instream use with a long history. The Lewis and Clark expedition journals and many of Mark Twain's novels illustrate the extent to which the Nation originally depended on adequate streamfiows for basic transportation. Navigation in the 1980's is still considered to be an instream use; however, it often is based upon a stream system that has been modified greatly through channelization, diking, and construction of dams and locks. The present (1987) inland water navigation system in the conterminous United States consists of about 12,000 miles of maintained waterways, over which about 500 million tons of cargo is carried each year (U.S. Army Corps of Engineers, 1988, p. 16). Although not so widely practiced in recent years, streams have been used to dispose of raw waste products from homes, communities, and factories. This use has been discouraged by law and public policy because of public health concerns and the damage it causes to the environment. Beginning in the mid-1960's, other instream uses gained new prominence in the water-resources arena-the assertion of a legal right to a free-flowing stream for biological, recreational, and esthetic purposes. These uses themselves, however, are not new. Riverine habitat always has produced fish, and the beauty of flowing water always has evoked a strong sense of esthetic appreciation. What is new is the emerging legitimacy and awareness of these noneconomic uses under State and Federal laws and regulations. In the past, environmental uses of flowing water were ignored, for the most part, under a long-standing legal tradition that favored offstream uses and certain instream uses that had a strong economic basis. The history of instream-flow policy debate really concerns those recently recognized types of interim uses. Although the more transitional water uses have been protected by law, the recognition of other in stream uses has resulted in substantial changes in State water laws. Although methods for determining the volume of water needed for most traditional water uses are relatively straight-forward and well-established, methods for determining water requirements for the in stream uses have been developed only recently and are continuing to evolve. Water laws that have favored the more traditional water uses, the inherent nature of conflict between instream and offstream water uses, and the special kinds of technological and philosophical problems posed by the "newer" types of instream uses are described below. Water laws that have been passed to accommodate the more recently recognized instream uses are summarized.

Report↗

Water resources planning under the Fish and Wildlife Coordination Act

This paper briefly discusses the more significant provisions of the Fish and Wildlife Coordination Act (1958). It covers pertinent aspects of legislative history, the development and current status (April 1980) of certain policies relevant to administering the Act, and other matters. It is directed primarily to practicing fish and wildlife agency field biologists, planners, and decisionmakers engaged in water resources development activities under the Act. It is not intended to be exhaustive in its treatment. The Fish and Wildlife Coordination Act provides a basic procedural framework for the orderly consideration of fish and wildlife conservation measures to be incorporated into Federal and Federally permitted or licensed water development projects. The principal provisions of the Act include: 1. a statement of Congressional purpose that fish and wildlife conservation shall receive equal consideration with other project features; 2. mandatory consultation with wildlife agencies with a view to achieving such conservation; 3. full consideration by action of the recommendations stemming from consultation; 4. authority for action agencies to implement such recommendations as they find acceptable. The FWCA in effect amends, conditions, or supplements other Federal laws and is thus closely linked in its application and interpretation. It is similarly linked to Federal planning standards and procedures. Because of this, interpretations tend to be flexible and evolve, adapting to changing situations. The following reference matrix outlines selected sections of the Fish and Wildlife Coordination Act which are of particular relevance to planners.

FWS/OBS↗

Geologic assessment of undiscovered, technically recoverable coalbed-gas resources in Cretaceous and Tertiary rocks, North Slope, and adjacent state waters, Alaska

The purpose of the U.S. Geological Survey's (USGS) National Oil and Gas Assessment is to develop geology-based hypotheses regarding the potential for additions to oil and gas reserves in priority areas of the United States, focusing on the distribution, quantity, and availability of oil and natural gas resources. The USGS has completed an assessment of the undiscovered, technically recoverable coalbed-gas resources in Cretaceous and Tertiary rocks underlying the North Slope and adjacent State waters of Alaska (USGS Northern Alaska Province 5001). The province is a priority Energy Policy and Conservation Act (EPCA) province for the National Assessment because of its potential for oil and gas resources. The assessment of this province is based on geologic principles and uses the total petroleum system concept. The geologic elements of a total petroleum system include hydrocarbon source rocks (source rock maturation, hydrocarbon generation and migration), reservoir rocks (stratigraphy, sedimentology, petrophysical properties), and hydrocarbon traps (trap formation and timing). In the Northern Alaska Province, the USGS used this geologic framework to define one composite coalbed gas total petroleum system and three coalbed gas assessment units within the petroleum system, and quantitatively estimated the undiscovered coalbed-gas resources within each assessment unit.

Alaska↗

South Florida Ecosystem Program of the U.S. Geological Survey

Introduction The South Florida Ecosystem Program is one of several study areas within the USGS Ecosystem Program. The Ecosystem Program was established to enable the USGS to enhance its scientific assistance to resource managers who require an improved scientific information base to resolve or prevent complex resource conflicts or environmental problems in specific ecosystem sites. Through 3-5-year efforts in each ecosystem site, USGS intensifies its provision of scientific information tailored to the specific management needs of that ecosystem. The information is designed to have a direct, significant, and immediate impact on management and policy decisions. It addresses regional or subregional issues that involve environmental resources such as water, minerals, and land. The sites may have as their focus such issues as water quality or water supply, environmental effects of mineral or energy use or extraction, effects of alterations in land use or land cover. Initially, the Ecosystem Program focussed on two ecosystems: San Francisco Bay and south Florida. Chesapeake Bay was added in FY 1996. Activities in each site last from three to five years, and additional ecosystem sites will be added as funding becomes available. The program is multidisciplinary and brings together scientists from appropriate disciplines to apply their diverse expertise to common problems. Disciplines in the present suite of ecosystems include land characterization, surface modeling, geospatial database management, ground- and surface-water hydrology, geophysics, ecology, geochemistry, paleontology, hydrologic modeling, and contaminant, sediment, and nutrient dynamics. The South Florida Ecosystem Program is an intergovernmental effort to reestablish and maintain the ecosystem of south Florida. One element of the restoration effort is the development of a firm scientific basis for resource decisionmaking. The U.S. Geological Survey (USGS) is one of the agencies that provides scientific information as part of the USGS South Florida Ecosystem Program. The Program, which was begun in fiscal year 1995, provides multidisciplinary hydrologic, cartographic, and geologic data that relates to the mainland of south Florida, the Florida Bay, and the Florida Keys and Reef ecosystems. The Program complements ongoing USGS work, such as the National Water-Quality Assessment Program , the Federal-State Cooperative Program, Marine and Coastal Geology Program and Regional Geology Program , and topographic mapping and digital cartography .

Florida↗

Taking the pulse of Colorado's Front Range: Developing regional indicators of environmental and quality of life condition

Indicators are routinely used to report the status and trends of human health, economy, educational achievement, and quality of life. Some environmental indicators, such as for water and air quality, are routinely reported and used to inform personal, management, or policy decisions. Other environmental indicators, particularly those that do not relate directly to human well-being, have been harder to define, interpret, or use. These indicators may be just as useful and important in describing the ability to provide ecosystem good and services, or less tangible quality of life measures, but they may be suspect because of the quality of data or even the source of the information.

Fact Sheet↗

Setting limits: Using air pollution thresholds to protect and restore US ecosystems

More than four decades of research provide unequivocal evidence that sulfur, nitrogen, and mercury pollution have altered, and will continue to alter, our nation's lands and waters. The emission and deposition of air pollutants harm native plants and animals, degrade water quality, affect forest productivity, and are damaging to human health. Many air quality policies limit emissions at the source but these control measures do not always consider ecosystem impacts. Air pollution thresholds at which ecological effects are observed, such as critical loads, are effective tools for assessing the impacts of air pollution on essential ecosystem services and for informing public policy. U.S. ecosystems can be more effectively protected and restored by using a combination of emissions-based approaches and science-based thresholds of ecosystem damage.

Issues in Ecology↗