New report: State of the Science on Restoring Western Headwater Mountain Streams

Trail Creek, Gunnison County, CO | Photo by Jackie Corday

Click the link to read the article on the American Rivers website (Hannah Holm):

As western mountain snowpacks diminish and wildfires race across parched landscapes, appreciation has grown for the moist mountain meadows and wetlands that hold water up high, feeding streams throughout the summer and providing fire-resistant refuges for wildlife. Before beavers and their dams were largely eliminated by the fur trade, these natural water storage features and refuges were common across western states’ mountain landscapes.

Beavers added to a LTPBR structure installed on Beaver Creek, Gunnison County, CO

The removal of beavers and other land disturbances have led many creeks to cut deeper into their valleys and detach from their floodplains, dropping the water table and drying out the landscape. A growing field of stream restoration, known as low-tech process-based restoration (LTPBR), seeks to reverse these changes through methods that mimic beaver activity in hopes of enticing them to return.

Projects across the west have demonstrated the benefits of LTPBR on the landscape. Projects have improved water quality, provided important habitat, trapped sediment, increased riparian vegetation and forage, and bolstered resilience against drought, fire, and floods. These benefits are achieved by installing low-tech, hand-built structures, creating “speedbumbs” that enable water from snowmelt and storms to spread across the riparian area, slowing peak flows and recharging groundwater. The rewetted soil “sponge” supports healthy riparian vegetation and reduces wildfire risks.

LTPBR project on Beaver Creek, Gunnison County, CO

As LTPBR projects have proliferated across western states, both excitement about their benefits and questions about potential impacts have grown. A new report from American Rivers reviews the published science and case study information on LTPBR to better understand the full range of benefits these projects can provide, and provides scientific evidence to address potential concerns. The report finds ample evidence for LTPBR benefiting habitat and buffering the impacts of droughts, floods, and wildfires, but concludes that more research is needed to better understand the full suite of ecosystem service benefits. It also provides insights on how to address human and social factors related to LTPBR projects, such as mitigating beaver dam impacts to infrastructure.



Paper: An Historical Perspective on the Accounting for Evaporation and System Losses in the Lower #ColoradoRiver Basin — Eric Kuhn and John Fleck #COriver #aridification

Diagram credit: USGS

Click the link to access the paper on the SSRN website (Eric Kuhn and John Fleck). Here’s the abstract:


Water management of the Lower Colorado River has long sidestepped the questions of how to account for and assess the impact of reservoir evaporation and system losses. To date, the preferred strategy has been to ignore those losses. The hydrologic gap left by this approach, which leaves an imbalance between the water flowing into Lake Mead and the amount released for downstream users, has been covered by simply releasing water stored in Lake Mead from the wet decade of the 1990s ensuring that no user bears the brunt of a legal interpretation that might reduce their supply. This disconnect between the river’s allocation framework and hydrologic reality is the result of longstanding governance failures by the U.S. and the Lower Basin states – Arizona, California, and Nevada – including failure of the U.S. to factor in reservoir and system losses in the 1944 Treaty with Mexico and failure of the states to negotiate a Lower Basin compact to apportion their share of the river.

Paper: The Devil they Knew:Chemical Documents Analysis of IndustryInfluence on #PFAS Science — Annals of Global Health

Credit: Gaber et al. Annals of Global Health

Click the link to read the paper on the Annals of Global Health website (Nadia Gaber, Lisa Bero, and Tracey J. Woodruff). Here’s the abstract:

Background: Per-and polyfluoroalkyl substances (PFAS) are a class of widely-used chemicals that persist in the environment and bioaccumulate in humans and animals, becoming an increasing cause for global concern. While PFAS have been commercially produced since the 1940s, their toxicity was not publicly established until the late 1990s. The objective of this paper is to evaluate industry documents on PFAS and compare them to the public health literature in order to understand this consequential delay.

Methods: We reviewed a collection of previously secret industry documents archived at the UCSF Chemical Industry Documents Library, examining whether and how strategies of corporate manipulation of science were used by manufacturers of PFAS. Using well established methods of document analysis, we developed deductive codes to assess industry influence on the conduct and publication of research. We also conducted a literature review using standard search strategies to establish when scientific information on the health effects of PFAS became public.

Results: Our review of industry documents shows that companies knew PFAS was “highly toxic when inhaled and moderately toxic when ingested” by 1970, forty years before the public health community. Further, the industry used several strategies that have been shown common to tobacco, pharmaceutical and other industries to influence science and regulation – most notably, suppressing unfavorable research and distorting public discourse. We did not find evidence in this archive of funding favorable research or targeted dissemination of those results.

Conclusions: The lack of transparency in industry-driven research on industrial chemicals has significant legal, political and public health consequences. Industry strategies to suppress scientific research findings or early warnings about the hazards of industrial chemicals can be analyzed and exposed, in order to guide prevention.


  1. This paper analyses how the chemical industry, using industry documents, delayed disclosing the harms of PFAS, costing billions of dollars in health and environmental damages globally.
  2. Many countries are pursuing legal and legislative action to curb PFAS production that may be aided by the timeline of evidence presented here.
  3. The production of chemical toxicity research should be in the best interest of protecting the public’s health, including designing the research question, funding studies, and publishing favorable and unfavorable findings.
  4. Legal settlements against chemical manufacturers should include documents disclosure in order to ensure transparency and accountability for industries and their products.
  5. Public health and environmental policy makers should move towards precautionary principles of chemical regulation.


This paper examines previously secret documents held by DuPont and 3M, the largest manufacturers of PFAS, also called “forever chemicals.” We show how the chemical industry used the tactics of the tobacco industry to delay public awareness of the toxicity of PFAS and, in turn, delayed regulations governing their use. PFAS are now ubiquitous in the population and environment. Consumer awareness can advance calls for safer products by demanding publicly available studies of harm. Public pressure can also influence legislators to pass more health-protective environmental and
chemical regulations.

As the U.S. Supreme Court debates a Navajo #water rights case, #ClimateChange adds new questions —

Navajo Mountain March 2023. Jonathan P. Thompson photo.

Click the link to read the article on the website (Joan Meiners). Here’s an excerpt:

“About 30, 40 years ago, we used to have plenty of rain,” [Percy] Deal said. “And there was a natural spring where water came out on its own. I remember when I was a little boy herding sheep, there was at least two or three places where the water came out. Those springs are dry now. People used to plant corn, squash, potatoes, beans and things like that. Now the ground is so dry that plants don’t grow anymore.”

News of water shortages, exacerbated by climate change, population growth, mining and other development, is everywhere these days in the American Southwest. But on the Navajo Reservation, a sovereign tribal nation that sits on about 16 million acres in northeast Arizona, southern Utah and western New Mexico, nearly 10,000 homes have never had running water.

How that can and should be resolved is one aspect of a case brought before the U.S. Supreme Court on March 20, with the justices’ decision due any day now…

In Arizona v. Navajo Nation (which has been consolidated with the case termed “Department of the Interior v. Navajo Nation”), tribal attorneys argue that, by not providing their nation with sufficient water, the United States has breached a trust obligation related to treaties settled in 1849 and 1868. 

At issue is the idea of what it means to “provide” water. All parties agree that the Navajo Nation has reserved water rights, termed Winters rights, that are supposed to “fulfill the purposes of the reservation,” including home and agricultural use. As the oldest users of water in this region, their rights also predate, and therefore outrank, those currently hotly contested between the seven Colorado River Basin states — Arizona, California, Utah, New Mexico, Colorado, Nevada and Wyoming.