Federal Statutes and Environmental Justice in the Navajo Nation: The Case of Fracking in the Greater Chaco Region

Arguing for the importance of robust public participation and meaningful Tribal consultation to address the cumulative impacts of federal projects, we bridge interdisciplinary perspectives across law, public health, and Indigenous studies. We focus on openings in existing federal law to involve Tribes and publics more meaningfully in resource management planning, while recognizing the limits of this involvement when only the federal government dictates the terms of participation and analysis. We first discuss challenges and opportunities for addressing cumulative impacts and environmental justice through 2 US federal statutes: the National Environmental Policy Act and the National Historic Preservation Act. Focusing on a major federal planning process involving fracking in the Greater Chaco region of northwestern New Mexico, we examine how the Department of the Interior attempted Tribal consultation during the COVID-19 pandemic. We also highlight local efforts to monitor Diné health and well-being. For Diné people, human health is inseparable from the health of the land. But in applying the primary legal tools for analyzing the effects of extraction across the Greater Chaco region, federal agencies fragment categories of impact that Diné people view holistically. (Am J Public Health. 2022;112(1):116–123. https://doi.org/10.2105/AJPH.2021.306562 )

Asymmetry drives the cumulative impacts of multiple stressors on freshwater ecosystems under a warming climate

Climate warming is an important stressor in freshwater ecosystems, yet its interactive effects with other environmental changes are poorly understood. We address this challenge by testing the ability of three contrasting null models to predict the joint impacts of warming and a second stressor using a new database of 296 experimental combinations. Despite concerns that stressors will interact to cause synergisms, we found that net impacts were best explained by the effect of the worst stressor (the dominance null model). When this stressor’s impact was at least 50% greater than that of the second, the dominance model was most accurate in 62% of responses. Prediction accuracy depended on the identity of the stressors and declined at higher levels of biological organisation. Together these findings suggest we can often effectively forecast impacts of multiple stressors by focusing on the degree of asymmetry that exists among their independent impacts.

Small artificial impoundments have big implications for hydrology and freshwater biodiversity

Headwater streams are critical for freshwater ecosystems. Global and continental studies consistently show major dams as dominant sources of hydrological stress threatening biodiversity in the world’s major rivers, but cumulative impacts from small artificial impoundments concentrated in headwater streams have rarely been acknowledged. Using the Murray Darling River basin (Australia)and the Arkansas River basin (USA) as case studies, we examine the hydrological impact of small artificial impoundments. The extent of their influence is significant, altering hydrology in 280 - 380% more waterways when compared to major dams alone. Hydrological impacts are concentrated in smaller streams (catchment area < 100 km2), raising concerns that the often diverse and highly endemic biota found in these systems may be under threat. Adjusting existing biodiversity planning and management approaches to address the cumulative effects of many small and widely distributed artificial impoundments presents a rapidly emerging challenge for ecologically sustainable water management.

Prioritizing Management for Cumulative Impacts

Determining where environmental management is best applied, either through regulating single sectors of human activities or across sectors, is complicated by interactions between human impacts and the environment. In this article, we show how an explicit representation of human-environment interactions can help, via "impact networks" including activities (e.g. shipping), stressors (e.g. ship strikes), species (e.g. humpback whales) or ecosystem services (e.g. marine recreation). Impact networks can enable the identification of "leverage nodes", which, if present, can direct managers to the activities and stressors crucial for reducing risk to important ecosystem components. Exploring an impact network for a coastal ecosystem in British Columbia, Canada, we seek to identify these leverage nodes using a new approach employing Bayesian Belief Networks of risks to ecosystems. In so doing, we address three key questions: (1) Do leverage nodes exist? (2) Do management plans for species correctly identify leverage nodes? (3) Does the management of leverage nodes for certain species realize benefits for other species and ecosystem services? We show that there are several leverage nodes across all species investigated, and show that preconceptions about the regulation of risk to species can misidentify leverage nodes, potentially leading to ineffective management. Notably, we show that managing fisheries does not reduce overall risk to herring whereas managing diverse cumulative impacts including nutrient runoff, oil spills, and marine debris can reduce risk to herring, additional species, and related ecosystem services. Thus, by targeting leverage nodes, managers can efficiently mitigate risks for whole communities, ecosystems, and ecosystem services.