Over the last five years, Learning By Doing has made significant progress toward fulfilling its mission to maintain and improve Grand County’s aquatic environment.
How much water do trees and bushes need during winter dry spells in Denver? Winter watering tips from Denver Water.
Denver Water is replacing a flume at Eleven Mile Dam to protect the river and increase climate resiliency.
Here’s the release The Colorado School of Mines (Emilie Rusch):
Published today in Environmental Science and Technology, the research was led by Mines’ Chris Higgins and Juliane Brown
If state and federal regulators focus only on the safety of drinking water, the public could still be exposed to concerning levels of poly- and perfluoroalkyl substances (PFASs) via the vegetables on their dinner plate if those vegetables are grown with PFAS-impacted water, according to a new study from researchers at Colorado School of Mines and engineering firm Geosyntec.
Published today in the journal Environmental Science and Technology, the study is the first of its kind to examine PFAS in water that is used to grow crops. Researchers compiled available data on how much individual PFASs are taken into vegetable crops irrigated with contaminated water – in this case lettuce – to estimate the daily dietary exposure intake through vegetables of these so-called “forever chemicals” for both adults and children.
“While there has been an emphasis on identifying and cleaning up drinking water impacted by PFASs, much less attention has been given to assessing risks from consuming produce irrigated with PFAS-contaminated water,” said Juliane Brown, an environmental engineering PhD candidate at Mines who led the research. “This study brings much needed attention to this issue and highlights the potential risks associated with this critical exposure pathway.”
PFASs are a large and diverse group of synthetic chemicals used in many commercial and household products, including Class B fire-fighting foams, nonstick-coated cooking pan production, food contact materials, waterproof textiles and many others. An emerging body of evidence shows PFAS exposure can cause cancer and developmental, endocrine, renal and metabolic problems.
Globally, PFAS contamination of irrigation water and soils in agricultural areas has arisen from a variety of sources, including the use of aqueous film forming foam (AFFF) on military bases and airfields, the application of treated sewage sludge as agricultural fertilizer and releases from nearby industrial facilities.
But currently, many state and federal agencies are primarily focused on drinking water exposure, missing a potentially importance exposure pathway via irrigation water, said Christopher Higgins, professor of civil and environmental engineering at Mines and senior author of the study.
“Even when drinking water has been treated and is considered safe, there is a potential for exposure from vegetables irrigated with contaminated water or grown in contaminated soil,” Higgins said. “This study shows that regulations that solely target perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) in drinking water are inadequate to protect human health risks from PFASs.”
By using statistical modeling techniques akin to the election model prediction forecasts, the Mines-led team was able to consider a range of variability and uncertainty to identify the “most likely” intake and hazard associated with consuming PFAS-contaminated vegetables, using lettuce as a proxy for produce. The team also predicted risk-based threshold concentrations in produce and irrigation water to provide screening levels for assessment. These represent the range of concentrations for individual PFASs in irrigation water predicted to be below a level of concern for human health.
Using the lowest available human health toxicity reference values and a conservative 5th percentile approach, estimated risk-based threshold concentrations in irrigation water were 38 nanograms per liter (ng/L) for PFOA and 140 ng/L for PFOS, two PFASs commonly targeted by regulators.
In the case of PFOA, this suggests that even if irrigation water meets the current 70 ng/L PFOA and PFOS U.S. Environmental Protection Agency lifetime health advisory for drinking water, this may not be fully protective of PFOA exposure due to vegetables grown in that water, at least compared to toxicity reference values used by the State of California, which has the lowest toxicity reference value for PFOA in the U.S., Higgins said. Importantly, PFAS contamination also typically includes more than just PFOA or PFOS.
“Another major implication of this study is we really need to come up with a plan to address PFAS mixtures, as these chemicals are nearly always present as a mixture,” Higgins said
The team used real-world data from PFAS-contaminated groundwater to conduct a hazard analysis of a theoretical farm comparing different risk estimates based on established state, federal, and international toxicity reference doses. This analysis showed estimated exposures to most PFASs exceeding available or derived human health toxicity reference values – indicating water-to-crop transfer is an important exposure pathway for agricultural communities with PFAS-impacted irrigation water.
The full study, “Assessing human health risks from per- and polyfluoroalkyl substances (PFAS)-impacted vegetable consumption: a tiered modeling approach,” is available online at https://dx.doi.org/10.1021/acs.est.0c03411. In addition to Brown and Higgins, co-authors were Geosyntec principal scientist Jason Conder and project scientist Jennifer Arblaster.
This research was supported, in part, by the National Science Foundation Graduate Research Fellowship and the U.S. Environmental Protection Agency (under Assistance Agreement No G18A112656081.)
Here’s the abstract:
Irrigation water or soil contaminated with per- and polyfluoroalkyl substances (PFASs) raises concerns among regulators tasked with protecting human health from potential PFAS-contaminated food crops, with several studies identifying crop uptake as an important exposure pathway. We estimated daily dietary exposure intake of individual PFASs in vegetables for children and adults using Monte Carlo simulation in a tiered stochastic modeling approach: exposures were the highest for young children (1−2 years > adults > 3−5 years > 6−11 years > 12−19years). Using the lowest available human health toxicity reference values (RfDs) and no additional exposure, estimated fifth percentile risk-based threshold concentrations in irrigation water were 38 ng/L (median 180 ng/L) for perfluorooctanoate (PFOA) and 140 ng/L (median 850 ng/L) for perfluorooctane sulfonate (PFOS). Thus, consumption of vegetables irrigated with PFAS impacted water that meets the current 70 ng/L of PFOA and PFOS U.S. Environmental Protection Agency’s lifetime health advisory for drinking water may or may not be protective of vegetable exposures to these contaminants. Hazard analyses using real-world PFAS- contaminated groundwater data for a hypothetical farm showed estimated exposures to most PFASs exceeding available or derived RfDs, indicating water-to-crop transfer is an important exposure pathway for communities with PFAS-impacted irrigation water.
From Water Education Colorado (Sarah Kuta):
Colorado’s anti-speculation water laws are considered some of the toughest in the West. Still, state lawmakers worry those laws may not go far enough. That’s why an 18-member work group is exploring ways to strengthen the rules. Recommendations for proposed changes are due by August 2021.
“In my mind, I think speculation is going on,” says Sen. Don Coram, a Republican who represents several Western Colorado counties and who co-sponsored SB20-048, which directed Colorado’s Department of Natural Resources to form the work group. “There are situations that are just not meeting the smell test for me. We need to look under the tent and see what’s going on.”
With water demand and prices soaring, lawmakers worry about loopholes in Colorado’s anti-speculation laws, pointing to recent investment group purchases of farmland and their senior water rights on the West Slope and in the San Luis Valley. So far, the investors are using the water for irrigation, a legally beneficial use, but lawmakers worry they’re making a speculative play, banking on a massive increase in the value of those rights with the intention to profit from them in the future. Irrigation may just be an interim placeholder that’s part of a larger investment strategy.
So, how will the work group’s members make recommendations for improvement? They’ll likely start with a thorough history lesson and a deep dive into existing anti-speculation law, says Kevin Rein, Colorado’s state engineer. Rein leads the group alongside Scott Steinbrecher, a Colorado assistant deputy attorney general. Other participants include water engineers, attorneys, members of the Colorado Water Conservation Board, farmers and ranchers, representatives of environmental nonprofits, and water managers. Given the diversity of group members and knowledge, the group is well-poised to tackle the challenge at hand, Rein says.
But some work group members are already contemplating how changes to Colorado water law could hurt landowners. Joe Frank, general manager of the Lower South Platte Water Conservancy District in northeastern Colorado, plans to participate in the work group with an open mind but has questions: How will the changes impact an irrigator’s ability to sell their water and land? Will the value of their land or water suffer because of these changes?
“There’s this tension here, especially in our basin, but also statewide, of a high demand for water, which inflates the value of it—it’s hard to blame farmers for wanting to sell their water because of all different kinds of circumstances,” Frank says. “We would prefer them to keep their water and stay in agriculture because that’s the economic base for our area. But you can’t just go say, ‘We’re going to put a stop to it.’ Now you’re impacting somebody’s property rights.”
Frank said he also has some questions about the constitutionality of any changes the group may propose.
“I do have some reservations about whether this will actually solve a problem without causing another one,” he says. “You don’t want to cause unintended consequences here.”
Sarah Kuta, a Nebraska native and graduate of Northwestern University, is a freelance writer based in Longmont, Colo.
Here’s an explainer for the High Plains A&M LLC speculation ruling from BLW Law (Stephen H. Leonhardt, Scott A. Clark and Alix L. Joseph). Here’s an excerpt:
High Plains A&M LLC filed two almost identical applications for changes of water rights in late 2002 and early 2003. The Water Court consolidated the two cases. In its Applications, High Plains claimed to own or control of about 30% of the shares in one of the largest irrigation systems in Colorado. High Plains asked the Water Court to approve changes to its water rights from irrigation and other decreed uses in the lower Arkansas River Valley to any beneficial use, including over fifty identified potential uses, in any location within twenty-eight Colorado counties. High Plains’ applications did not identify any end users of the water besides the farmers who currently use the water. In High Plains A&M, LLC v. Southeastern Colorado Water Conservancy District, 120 P.3d 710 (Colo. 2005), Burns, Figa & Will, P.C., on behalf of our client, the Southeastern Colorado Water Conservancy District, successfully argued that High Plains’ application for a change of water right was properly dismissed because the application did not state with specificity the use or location of use of the changed water rights, thus violating Colorado’s anti-speculation doctrine.
From email from Reclamation (Susan Novak Behery):
In response to decreasing tributary flows, the Bureau of Reclamation has scheduled an increase in the release from Navajo Dam from 300 cubic feet per second (cfs) to 350 cfs on Saturday, November 21st, starting at 4:00 AM. Releases are made for the authorized purposes of the Navajo Unit, and to attempt to maintain a target base flow through the endangered fish critical habitat reach of the San Juan River (Farmington to Lake Powell).
The San Juan River Basin Recovery Implementation Program recommends a target base flow of between 500 cfs and 1,000 cfs through the critical habitat area. The target base flow is calculated as the weekly average of gaged flows throughout the critical habitat area from Farmington to Lake Powell.
From The Revelator (Tara Lohan):
Some parts of the United States could easily generate 10 times their energy needs, according to a new report.
How much of U.S. energy demand could be met by renewable sources?
According to a new report from the Institute for Local Self-Reliance, the answer is an easy 100%.
The report looked at how much renewable energy potential each state had within its own borders and found that almost every state could deliver all its electricity needs from instate renewable sources.
And that’s just a start: The report found that there’s so much potential for renewable energy sourcing, some states could produce 10 times the electricity they need. Cost remains an issue, as does connecting all of this capacity to the grid, but prices have dropped significantly, and efficiency continues to improve. Clean energy is not only affordable but could be a big boost to the economy. Locally sourced renewables create jobs, reduce pollution, and make communities more climate resilient.
So where are the opportunities? Rooftop solar, the study found, could supply six states with at least half of their electricity needs. But wind had the greatest potential. For 35 states, onshore wind alone could supply 100% of their energy demand, and offshore wind could do the same in 21 states. (The numbers overlap a bit.)
The study follows a similar report conducted a decade ago and shows that the clean energy field has made substantial progress in that time.
The Revelator spoke with Maria McCoy, a research associate at the Institute and report co-author, about what’s changed and how to turn all the potential into reality.
What’s changed in the 10 years since you last looked at the potential for instate renewable energy?
There’s definitely been technology improvements in all the energy sources, but especially solar. Obviously there’s the same amount of sun, but the solar panels themselves have a higher percentage of solar photovoltaic efficiency. Most states, on average, had 16% more solar potential this time around than they did a decade ago.
And for the other technologies, it’s a matter of either more space being available or the technologies themselves improving. Wind turbines now can generate a lot more energy with the same amount of wind.
Where do you see the most potential?
There’s been a lot of development in offshore wind and I think it’s on the cusp of really becoming a big player in the clean energy field. But regulations, including at the federal level, have blocked it from happening at scale in the United States. Whereas in Europe there’s already some incredibly efficient offshore wind farms that are generating a lot of electricity. Those companies are just starting to move into the U.S. market.
But it’s onshore wind that has the biggest potential. Our research found that some states could generate over 1,000% of their energy with onshore wind if they really took advantage of it.
Your report didn’t consider the potential of large-scale solar. Why?
We looked at the potential of rooftop solar rather than large-scale solar because as an energy democracy organization, we’re really focused on distributed and community-owned energy. But it’s also because pretty much every state has enough capacity to completely be powered by large-scale solar. It just then becomes an issue of land-usage debates and other challenges.
Your research shows there’s a ton of potential for renewables across the country. How do we realize that potential?
Continued support for renewable energy is a big one. There are a lot of credits that are phasing out and without renewing those, it will make it a little bit tougher for the market.
We were looking at just the technical ability to produce the energy and not necessarily the cost effectiveness, but we did recognize in the report that the costs have come down. The cost of solar PV, for example, has dropped 70%. So this is not really a pie-in-the-sky goal. It’s definitely gotten a lot more feasible and many cities are already doing it or planning to in the near future.
I think the will is there and people want renewable energy, it’s just a matter of fighting the status quo. A lot of these utilities have been using the same business model for decades and they’re not really keeping up with where things are going and where the community wants things to go.
They’re holding on to their fossil fuel infrastructure and their business model that profits off building more fossil gas plants when solar plus storage is already a cheaper energy source for customers. And wind is very cheap. If utility regulators and state and national policy could hold these utilities accountable to serving the public, which is their job as regulated monopolies, we could finally get to see some of this potential becoming a reality.
Having the ability to generate energy locally and store it and use it locally will create jobs and provide a lot of resilience to the grid and communities. And with climate change, I think that’s becoming more and more important.
Was there anything that surprised you about your findings?
We definitely expected things to be better but I don’t know if we expected them to be this much better in 10 years. Seeing all this potential and these ridiculously high percentages — I mean, being able to generate greater than 1,000% of the electricity we need with renewables in some states is just a sign of how abundant clean energy is.
And it’s kind of sad, I guess, that some states aren’t even able to get to 25% or 50% clean energy goals in their renewable portfolio standards. I would hope that the train starts rolling a little faster.
And I hope our research can inspire others who think maybe their state doesn’t have a lot of renewable energy capacity in their area to realize that they do, and it could provide for all that they need and more.