Environmental News
Environmental News from Boulder, Colorado
CU study: Spruce beetle infestation in N. Colo. tied to drought
Oct 10th
The new study is important because it shows that drought is a better predictor of spruce beetle outbreaks in northern Colorado than temperature alone, said lead study author Sarah Hart, a CU-Boulder doctoral student in geography. Drought conditions appear to decrease host tree defenses against spruce beetles, which attack the inner layers of bark, feeding and breeding in the phloem, a soft inner bark tissue, which impedes tree growth and eventually kills vast swaths of forest.
Spruce beetles, like their close relatives, mountain pine beetles, are attacking large areas of coniferous forests across the West. While the mountain pine beetle outbreak in the Southern Rocky Mountains is the best known and appears to be the worst in the historical record, the lesser known spruce beetle infestation has the potential to be equally or even more devastating in Colorado, said Hart, lead author on the new study.
“It was interesting that drought was a better predictor for spruce beetle outbreaks than temperature,” said Hart of the geography department. “The study suggests that spruce beetle outbreaks occur when warm and dry conditions cause stress in the host trees.”
A paper on the subject was published online in the journal Ecology. Co-authors include CU-Boulder geography Professor Thomas Veblen; former CU-Boulder graduate student Karen Eisenhart, now at Edinboro University of Pennsylvania; and former CU-Boulder students Daniel Jarvis and Dominik Kulakowski, now at Clark University in Worcester, Mass. The National Science Foundation and the National Geographic Society funded the study.
The new study also puts to rest false claims that fire suppression in the West is the trigger for spruce beetle outbreaks, said Veblen.
Spruce beetles range from Alaska to Arizona and live in forests of Engelmann spruce and subalpine fir trees in Colorado. The CU-Boulder study area included sites in the White River, Routt, Arapaho, Roosevelt and Grand Mesa national forests as well as in Rocky Mountain National Park.
The CU-Boulder team assembled a long-term record of spruce beetle outbreaks from the northern Front Range to the Grand Mesa in western Colorado using a combination of historical documents and tree ring data from 1650 to 2011. Broad-scale outbreaks were charted by the team from 1843-1860, 1882-1889, 1931-1957 and 2004 to 2010.
The researchers used a variety of statistical methods to tease out causes for variations in the dataset at 18 sites in Colorado. “The extent to which we could distinguish between the warming signals and the drought signals was surprising,” said Veblen. “These are two things that easily can get mixed together in most tree ring analyses.”
There are several lines of evidence that drought is the main driver of the spruce beetle outbreak. The new study showed when northwest Colorado was in a warm, wet climate period from 1976 to 1998, for example, both spruce beetle reproduction and tree defenses like “pitching” beetles out of tree interiors with resin were likely high. But during that period of warming, outbreak was minimal.
The strongest climate correlation to spruce beetle outbreaks was above average annual values for the Atlantic Multi-decadal Oscillation, or AMO, a long-term phenomenon that changes sea-surface temperatures in the North Atlantic. Believed to shift from cool to warm phases roughly every 60 years, positive AMO conditions are linked to warmer and drier conditions over much of North America, including the West.
Veblen said the AMO shifted from its cool to warm phase in the 1990s, meaning the climate phenomenon could be contributing to drought conditions in the West into the middle of this century. A 2006 tree-ring study involving Veblen, his former student, Thomas Kitzberger and researchers from several other institutions concluded that the warm phase of AMO also was correlated to increased wildfires in the West.
In addition to AMO, the researchers looked at two other ocean-atmosphere oscillations — the El Nino Southern Oscillation and the Pacific Decadal Oscillation — as well as past temperatures, precipitation and aridity to better understand the spruce beetle outbreaks. The team found that another effective predictor of drought conditions was summer “vapor pressure deficit,” a measurement of atmospheric dryness, said Veblen.
In the new study, the researchers were particularly interested in “radial growth” rates of tree rings from sub-canopy trees of various species in the study areas that thrived following outbreaks. One hallmark of spruce beetle outbreaks is that slow radial growth rates in such areas are followed by extremely rapid radial growth rates, an indication smaller trees flourish in the absence of the larger spruce trees because of decreased competition for water and increased opportunities for photosynthesis, said Hart.
The area of high-elevation forests affected by spruce beetles is growing in the West, Hart said. “In 2012, U.S. Forest Service surveys indicated that more area was under attack by spruce beetles than mountain pine beetles in the Southern Rocky Mountains, which includes southern Wyoming, Colorado and northern New Mexico,” she said. “The drought conditions that promote spruce beetle outbreak are expected to continue.”
One big concern about spruce beetle outbreaks is their effects on headwater streams that are important for water resources, said Veblen. “In the short term, trees killed by spruce beetles will lead to less water use by trees and more water discharge into streams. But in the long term, the absence of the trees killed by beetles may lead to less persistence of snow and earlier runoff.”
Veblen said it might seem counterintuitive to some that spruce-fir subalpine forests in Colorado are larger by area than lodgepole/ponderosa pine forests. “It is probably because spruce and subalpine forests are found in more remote areas not as visible to most people,” he said. “But potentially, the current spruce beetle outbreak could affect a larger area than the mountain pine beetle outbreak.”
The study had its beginnings in 1986, when Veblen and his students began compiling spruce and subalpine fir tree rings from various study sites in the Colorado mountains. Tree rings from individual trees — which carry information about weather, climate and even events like volcanic eruptions — can be matched up and read with rings from other trees, much like the pages of a book, from year to year and even from season to season.
-CU-
Update: City of Boulder water is good; Left Hand water not so much
Sep 14th
The city’s Betasso Water Treatment Facility is operational and continues to deliver safe drinking water to city residents. However, due to high levels of turbidity in the Boulder Reservoir, the Boulder Reservoir Water Treatment Facility is not able to treat drinking water at this time and was not brought back online as the city had planned. While the Betasso facility has the ability to deliver water to all city customers, the city does not have redundancy in water treatment with the Boulder Reservoir Water facility offline. The city is urging water customers to use water conservatively until the Boulder Reservoir facility is operational again. This will allow the city to conserve and extend water treatment resources at the Betasso facility.
Additionally, the city’s wastewater treatment facility is experiencing unprecedented flows and system anomalies. A reduction in water use will help alleviate the pressure on the wastewater collection system.
Update on the wastewater pipeline breach
Yesterday, the city announced a breach in the main wastewater pipeline that carries 90 percent of the city’s wastewater to the treatment facility. However, today’s assessment indicated that there was not a breach in the suspected location. While good news, the condition of the wastewater currently arriving at the treatment facility does indicate that there are other issues throughout the collection system. City staff continues to assess and resolve these collection system deficiencies.
Many Boulder residents have been reporting that water or sewage is backing up into their homes. In most cases, this is groundwater and floodwater, not untreated wastewater (sewage). Excess stormwater in the drainage system and saturated soils are causing groundwater and floodwater to back up into private residences. However, if residents see or smell solid waste, they should call the Emergency Call Center at 303-413-7730 and ask that the issue be reported to Public Works crews. These backups could still be the result of issues on private property, but the city would like to gather the information to determine if it indicates a system failure.
Residents with isolated groundwater and floodwater backups may stay in their homes. However, if the water is wastewater, residents should use their own discretion to determine whether or not their homes are safe to stay in. These incidents are expected to decrease as the floodwaters recede.
Note about calls from Left Hand Water District
Some City of Boulder water customers received a phone call from the Left Hand Water District announcing a boil water order. If you are a City of Boulder water customer, you do not need to boil your water. The phone call was sent to a geographic area, but there are City of Boulder water customers in that area too and some got the call inadvertently. Check your water bill to determine who your water provider is. If you are in an HOA or a multifamily or rental unit and your water bill is paid by the HOA or your landlord, ask them to confirm who provides your water.
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Boulder: Let the sun shine on city’s energy future
Sep 10th
The City of Boulder announced today that it will create a working group of solar industry specialists and customers – both current and future – to explore motivators and barriers to implementing more solar throughout the community. The focus of the group’s work will be on defining the next-generation of incentives as well as providing guidance about how to handle solar contracts between now and the time when the city decides whether it will create a local electric utility.
“Supporting and increasing renewable sources of energy is a core value, and we see this discussion as an important next step in our effort to create the electric utility of the future,” said Heather Bailey, executive director of Energy Strategy and Electric Utility Development.
Bailey said the city has a unique opportunity to benefit from local experts to design programs that will encourage more local energy production. Expertise from the university and federal labs, as well as the numerous companies and entrepreneurs developing leading-edge energy technologies, has already helped Boulder achieve one of the highest levels of solar per-capita in the US, with close to 14 megawatts installed in the city.
The City of Boulder has also played a significant role in supporting local energy generation, particularly solar. This has included streamlining the permitting process to offering a local solar rebate and grant program. The concept of Solar Gardens was originally conceived in Boulder, and city staff members were on the drafting team of legislation that allowed this. The solar gardens law was signed by then-Governor Bill Ritter overlooking the Flatirons from a parking lot rooftop along the Pearl Street Mall.
“We don’t want to simply continue this tradition; we want to make it even stronger by working with stakeholders to identify ways to encourage even more locally generated clean energy sources. This is fundamental to achieving our community’s goals, whether we create our own electric utility or strike a new agreement with our current provider, Xcel Energy,” Bailey said.
One of the questions the city would like to resolve is how to encourage continued participation in solar installations during the ongoing deliberation about – and possible transition to – a local electric utility. Xcel Energy recently sent the city a letter requesting that the city agree to take over contracts it has with customers if Boulder forms an electric retail utility.
The City of Boulder is committed to protecting those who have made investments in solar energy in our community from any adverse impact related to the creation of a municipal utility. The city is also interested in working with Xcel on this important issue, not only to protect those who have already made investments, but to encourage growth in this area of renewable energy.
Boulder has no way, however, of evaluating the estimates that Xcel has made about these costs.
“Before we can agree to any arrangement, we need more information from Xcel Energy,” City Attorney Tom Carr said. “The company so far has declined most of the requests for data the city has made. Without detailed information about these contracts, we have no way of verifying Xcel’s assertions and perhaps more importantly, of making sure we are doing the right thing to protect our forward-thinking customers and other ratepayers.”
The city’s Energy Future team anticipates holding the first meeting of the solar working group shortly after the Nov. 5 election. Members of the community and industry who are interested in participating are encouraged to contact Heather Bailey at 33-441-1923 or baileyh@bouldercolorado.gov.
More information about the Energy Future project is available at www.BoulderEnergyFuture.com.
–CITY–