Hydraulic fracturing is a controversial method of extracting natural gas from shale deposits. S&S has explored this issue before, however, in advance of a highly anticipated report due out from the EPA in 2014 we wanted to introduce S&S readers to some of the impacts that hydraulic fracturing can have on water resources. In this first of 5 posts we will address the issue of water acquisition.
Let’s begin with the amount of water a hydraulically fracked well consumes. First, it is important to understand that when we say “consume” we mean something very specific. Consumed water is either not returned to the environment (in the case of fracking about 80% will typically remain trapped in the bedrock) or is not returned in a form that is healthy for humans or ecosystems to utilize. So while residential wastewater can reliably be treated to a point that meets federal or state standards before being returned to the environment, hydraulic fracturing wastewater even following treatment has been associated with elevated levels of pollutants that would violate the same standards.
According to numerous sources the hydraulic fracturing of a single well can consume between 2 and 10 million gallons of water. In the Marcellus the average figure is at 4.4 million gallons per well. These are lifetime estimates, which account for the fact that each well often needs to be fracked multiple times to extract all of the gas. These second and third stage fractures can take place several years after the original fracture, so the demand for water can be spread out over a number of years.
When aggregated and compared to other water uses at a national level 2-10 million gallons of water per well appears small, representing less than 1% of total US water consumption; however, locally the impacts can be greater. This is because some of the most active hydraulic fracturing regions also happen to be some of the most water stressed regions of America. For example, in arid states such as Texas and Colorado, certain counties report up to 50% of municipal water withdrawals are attributed to hydraulic fracturing. Further, farmers in Colorado have reported that gas companies have exponentially driven up prices for those water resources that are bid on at auction, clearly suggesting that the practice of hydraulic fracturing can put stress on scarce supplies. So while nationally hydraulic fracturing does not consume much water compared to say agriculture, which accounts for the majority of US water withdrawals, locally the impacts can be significant. As climate change has increased drought conditions in these same states it is clear that looking at water withdrawals associated with hydraulic fracturing only in relation to overall national consumption is misleading.
Finally, it is important to note that water withdrawals for fracking do not always come out of municipal supply lines but rather are sometimes taken directly from the natural environment, that is, from lakes, streams or aquifers (saline and fresh). When this is the case withdrawals should be carefully regulated and seasonally adjusted to allow for sufficient environmental flows especially in the small headwater streams that are currently supplying some wells in Pennsylvania.
Anecdotally it appears the gas industry is paying attention to the issue of water acquisition. For example, as of 2010 about 47% of the water used in fracking in Pennsylvania was recycled water from prior fracking operations. Further, some companies are in fact investigating seasonal water harvesting so as to disturb natural ecosystems the least during the driest months.
The possibility that natural gas represents a cleaner alternative to coal certainly should not be ruled out on the basis of water consumption alone. But development of shale gas clearly cannot be pursued without careful regulation of water acquisition practices at the local level. In subsequent posts we will explore the 4 other concerns that EPA is investigating with respect to water resource risk and hydraulic fracturing: chemical mixing, well injection, flowback and produced water, and wastewater treatment and waste disposal.
Image Credit: By Fflavio74 (own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)]