149
agricultural land may have less of an impact, and could even lead to a slight ecosystem improvement by displacing some of the area previously contributing chemical
pesticides and fertilizers to streams and groundwater. In an urbanized area, replacing an impervious parking lot with an equal-size impervious drill pad should have
no significant effect at all.
The NETL assessment was done using only numerical models. Some on-theground measurements in a variety of different land use areas would help to provide
rigorous data on the potential impacts of drill pads on small watersheds and aquatic
ecosystems. High-intensity storm water runoff is exceedingly stressful to aquatic
biota, and an ecosystem can require a substantial length of time to re-establish after
such an event. Another important consideration is that as drilling technology
improves, the pads are being spaced farther apart and the watershed impacts will be
different depending on when the pad was constructed. These historical changes in
well spacing must be considered in any field-based study. Environmental monitoring of shale well leases on state forest land in Pennsylvania has been carried out by
state agencies, and these data could be helpful in developing more robust models of
the hydrologic impacts of well pads on small watersheds in forested lands
(Pennsylvania Bureau of Forestry 2018).
The number of horizontally-drilled shale gas and tight oil wells in the United
States has increased in a decade from roughly 28,000 in 2007 to approximately
127,000 in 2017 (Mumford et al. 2020). There is at least some empirical evidence
reported by investigators at Penn State (Brantley et al. 2014) that the development
of shale gas resources has affected nearby stream ecosystems. Several recent investigations by the USGS have looked in detail at the potential impacts to groundwater,
streams and aquatic ecosystems from fracking and other shale gas activities. In most
cases, few significant links have been found (i.e. McMahon et al. 2015, 2016,
2017, 2019).
When surface water contamination does occur, the origins are usually not mysterious. For example, a UIC well in West Virginia used for the disposal of produced
water from the Marcellus Shale was found to be causing impacts to a nearby stream
(Akob et al. 2016). The contamination had little to do with the UIC well or the injection process itself, but was primarily caused by careless handling of the produced
water, resulting in spills from the trucks and leaks from loose plumbing connections
that were then getting into the creek. In another case, a North Dakota stream was
contaminated from a ruptured pipeline carrying Bakken produced water to a disposal well (Cozzarelli et al. 2017). These incidents can cause serious disruptions to
local aquatic ecosystems when they do happen, but fortunately they are infrequent.
The discharge of high-salinity produced water into streams during the early days
of the shale gas boom (2008–2012) caused noticeable declines in aquatic life.
Freshwater mussels, an endangered and protected species, were particularly affected
(Patnode et al. 2015). USGS measurements of mussel mortality combined with conductivity measurements in the Allegheny River downstream from POTW outfalls
and brine treatment facilities showed a significant population drop attributed to the
discharge of high TDS produced water. Changes in water management procedures
including the recycling of flowback and disposal of residual waste down UIC wells
were critical to the survival of native mussel populations in this river.
8.3 Aquatic and Marine Ecosystems
agricultural land may have less of an impact, and could even lead to a slight ecosystem improvement by displacing some of the area previously contributing chemical
pesticides and fertilizers to streams and groundwater. In an urbanized area, replacing an impervious parking lot with an equal-size impervious drill pad should have
no significant effect at all.
The NETL assessment was done using only numerical models. Some on-theground measurements in a variety of different land use areas would help to provide
rigorous data on the potential impacts of drill pads on small watersheds and aquatic
ecosystems. High-intensity storm water runoff is exceedingly stressful to aquatic
biota, and an ecosystem can require a substantial length of time to re-establish after
such an event. Another important consideration is that as drilling technology
improves, the pads are being spaced farther apart and the watershed impacts will be
different depending on when the pad was constructed. These historical changes in
well spacing must be considered in any field-based study. Environmental monitoring of shale well leases on state forest land in Pennsylvania has been carried out by
state agencies, and these data could be helpful in developing more robust models of
the hydrologic impacts of well pads on small watersheds in forested lands
(Pennsylvania Bureau of Forestry 2018).
The number of horizontally-drilled shale gas and tight oil wells in the United
States has increased in a decade from roughly 28,000 in 2007 to approximately
127,000 in 2017 (Mumford et al. 2020). There is at least some empirical evidence
reported by investigators at Penn State (Brantley et al. 2014) that the development
of shale gas resources has affected nearby stream ecosystems. Several recent investigations by the USGS have looked in detail at the potential impacts to groundwater,
streams and aquatic ecosystems from fracking and other shale gas activities. In most
cases, few significant links have been found (i.e. McMahon et al. 2015, 2016,
2017, 2019).
When surface water contamination does occur, the origins are usually not mysterious. For example, a UIC well in West Virginia used for the disposal of produced
water from the Marcellus Shale was found to be causing impacts to a nearby stream
(Akob et al. 2016). The contamination had little to do with the UIC well or the injection process itself, but was primarily caused by careless handling of the produced
water, resulting in spills from the trucks and leaks from loose plumbing connections
that were then getting into the creek. In another case, a North Dakota stream was
contaminated from a ruptured pipeline carrying Bakken produced water to a disposal well (Cozzarelli et al. 2017). These incidents can cause serious disruptions to
local aquatic ecosystems when they do happen, but fortunately they are infrequent.
The discharge of high-salinity produced water into streams during the early days
of the shale gas boom (2008–2012) caused noticeable declines in aquatic life.
Freshwater mussels, an endangered and protected species, were particularly affected
(Patnode et al. 2015). USGS measurements of mussel mortality combined with conductivity measurements in the Allegheny River downstream from POTW outfalls
and brine treatment facilities showed a significant population drop attributed to the
discharge of high TDS produced water. Changes in water management procedures
including the recycling of flowback and disposal of residual waste down UIC wells
were critical to the survival of native mussel populations in this river.
8.3 Aquatic and Marine Ecosystems