Download Artificial Snow Production for Winter Sport Recreation

Artificial Snow Production for Winter Sport Recreation and the
Resulting Effects on Water Quality and Macroinvertebrate Community
in Alpine Streams
Willa Capobianco
Taylor Kravits
Jason Scholz-Karabakakis
Francis Oggeri
Andrew Shaw
Executive Summary:
Primary Issue
Ski resorts draw millions of gallons of water from nearby sources and pump it to higher
elevations to be used as snow cover. This high water consumption, coupled with additive factors,
could cause problems to both water source and the receiving mountain stream ecology.
The goal of this paper is to determine risk to of; additives, chemicals, or biological factors have
on stream water quality and macroinvertebrate communities; water withdrawing requirements for
snow production, and its effects; salts applied to designated ski trails.
Purpose Statement
The purpose of this paper is to provide an insight of the effect of ski resorts on water quality and
macroinvertebrate communities through the production of artificial snow, trail “salting” for ski
racing, and water withdrawal from nearby rivers. The objectives of this paper are:
• Determine what types of major snow additives are used in artificial snow production
• Estimate yearly loads of additives on a watershed
• Establish risks associated with chemical groups found in additives and racing salts on stream
water quality and aquatic communities.
• Identify volume of water withdrawn for artificial snow production.
• Formulate recommendations for improving and reducing risk associated with producing and
maintaining artificial snow.
Key Recommendations
Using snow additives does not pose a significant risk, however because available research is
limited, and as a precautionary measure, several steps can be taken to minimize the risk of
uncertainties.
These measures are: limiting additives to those that do not contain trade secret proprietary
formulas, as third party testing is often non-existent or limited, using biological or mineral
compounds that play a natural role in snow/cloud formation so there are fewer uncertainties, and
creating retention/settling pond. Ski resorts should strive for increasing annual efficiency with
regard to water withdrawals.
Introduction:
Problem Statement:
In Vermont, revenue from ski slopes is an important part of the economy that draws in
approximately 19 million dollars every year in the winter (UVM, 1999). Artificial snow is
produced with chemical additives and water is drawn from surface water to create pre-season ski
trails on mountains. The impact of artificial snow is not yet understood. We examined the effects
of producing artificial snow with chemicals, water withdrawal, addition of salts to the slopes, and
what alternatives may exist.
Justification:
The chemical additives found in snowmaking are important problems to look at in relation to
ecological effects including water quality and water uptake from natural sources of water. The
winter sports recreation industry relies heavily on artificial snow production to start the ski season
earlier and to sustain it up to 2-4 weeks longer (Keller et al., 2004; Rixen et al., 2004).
Considering the forecasted predictions based on climate models, it can be conjectured that
increasing global temperatures will lead to an increased dependence on and use of artificial snow
(Rivera et. al, 2004).
The issue of water withdrawal for the use of snowmaking and its effects on macroinvertebrates
becomes another cause for concern. Macroinvertebrate populations can be used as indicators for
overall stream health. The state of Vermont has done testing on local streams of various ski
resorts in order to observe the health of the streams. Ski resorts such as Jay Peak, Smuggler’s
Notch, Bolton Valley, and Stowe have been listed as having adverse effects to aquatic life, biota
and habitat because of the withdrawal of water for snowmaking (VDEC, 2010). Water
withdrawal also decreases flow rate within streams (VDEC, 2010). A greater understanding of
these ecological ramifications is needed. This lends itself to a requisite for research and increased
ecological design around artificial snow production.
Methods/Approach:
Search engines (Google Scholar) and Internet journal databases (Web of Science) were searched
for articles relating to the production of artificial snow. Resources were evaluated for original
scientific integrity and used to assess the possible risks of snowmaking. Several widely
mentioned compounds (see Table 1) were identified and examined for possible environmental
effects, and specifically, any correlating effect on macroinvertebrates. Due to proprietary
regulations not all chemicals used in additives were disclosed, and some chemicals lacked
adequate research on their potential impacts. In these cases similar compounds were used to
speculate possible impacts on the environment. Numerous resorts in Vermont were contacted
about their water withdrawals, additives used and other snow production factors. These figures
were taken into consideration along with the reviews of available literature. For specific
additives, standard Material Safety Data Sheet (MSDS) forms were consulted to evaluate
potential threats.
Findings:
Many times there was no direct research done between snow additives and macroinvertebrate
communities. Inferences were made between available toxicological data, degradability, and
manufacturers reports.
Artificial Snow Additives Found:
Biological
Chemicals
Salts
Snowmax
Drift
Ammonium Nitrate
Ammonium Chloride
Ammonium Sulfate
Potassium Chloride
Sodium Chloride
Table 1: A list of commonly used additives for snow production and altering trail conditions.
With the advancement of delivery systems, proprietary formulas have been developed to alter the
conditions needed for the production of artificial snow, based on a survey sent out to local
Vermont ski resorts. Depending on weather conditions, additives can be injected into the water
used in this process. These additives can include gases such as carbon dioxide and liquid nitrogen
(Ritter, 2004). Another additive is silver iodide, an ice nucleation agent that is commonly used in
cloud seeding (Super, 1988). This practice has largely been discontinued, but is used to facilitate
cloud formation and initiate precipitation. Though silver iodide has a high LD50, the MSDS
states that “long term degradation products may arise.” It goes on to say that “the products of
degradation are more toxic” (MSDS). The potential chronic health effects of exposure to this
compound remain unknown. There were no further studies found on these additives or their
conjunctive use with other ingredients.
Other additives such as kaolinite a mineral used in soaps and detergents. This clay particle
enhances ice crystal formation; it is also the main ingredient in porcelain. By itself this product is
not known to be extremely harmful however, “when contaminated with silica it may produce
severe lung effects” (MSDS).
While many of these compounds that are not proprietary and are every day materials, the effect of
essentially atomizing these compounds in low temperatures has not been tested for the formation
of new, unintended secondary compounds. It is possible that using several different additives
could form such compounds. There really has not been much testing on this or the above
mentioned compounds with regard to their use on ski pistes to assess components of ecosystem
health, and nothing specifically on macroinvertebrates. The use of nitrates found in racing salts
and unfiltered stream or lake water sometimes results in a fertilizing effect, increasing biomass on
the mountain and altering species dynamics (Rixen et. al, 2003).
Salts are not used for artificial snowmaking but are applied to ski trails to improve the quality of
snow for races. The salt crystals break up into ions; these ions lower the freezing point of the
snow, which hardens the surface. This provides a dense layer of snow with a consistent surface.
Chlorides and nitrates are the most common salts used on ski trails. They are added after the snow
has been dispersed on the trails for the purpose of hardening the snow by creating an icy surface
(Rixen et. al, 2003). Different salts are used depending on weather and snow conditions because
they vary in their snow melting properties. Among the most common salts are ammonium nitrate,
ammonium chloride, ammonium sulphate, potassium chloride, sodium chloride and phosphates.
Few studies have addressed the ecological effects salts have on ski trails. One study on an Oregon
ski trail found that 500,000 kg of salts were used from May to September to sustain summer
skiing (Rixen et. al, 2003). It was found that chloride concentrations of streams within the
drainage of the snow field were 30 mg/L compared to 1–6 mg/L found in a stream outside the
drainage of the snowfield (Rixen et. al, 2003). Increasing chloride concentrations can be toxic to
stream life, EPA lists standards for acute and chronic levels at 860mg/L and 230mg/L. Currently,
levels of chloride in some streams adjacent to ski slopes are still well below those levels, however
ski resorts can add more salts to slopes each year to lengthen seasons. Nitrate salts have great
fertilizing properties leading to increases in vegetative biomass in alpine meadows, however
nitrate salts also result in water acidification, eutrophication, and direct toxicity of inorganic
nitrogen compounds (Rixen et. al, 2003). With addition of salts to ski slopes leading to increased
chloride concentrations, acidity, eutrophication, and nitrogen pollution in streams and watersheds,
Europe has set restrictions for salting ski trails and it is now only allowed when necessary
(Teichrob et. al, 2009).
Chloride salts are widely used in road salts and, consequently, stormwater and snowmelt runoff
often contain high concentrations of chloride in areas of application. A study in Colorado
determined that “aquatic insects are very sensitive to high chloride levels” (Bialasieweiz, 1999).
Other studies have been conducted on the effects of road de-icing salts on the environment. These
salts are very similar to the ones used for salting ski trails. Areas impacted by deicing salts have
been observed to have greater influxes in Na, Ca, and Cl in nearby streams with Cl concentrations
remaining elevated throughout the year (Wemple et. al, 2007). In urban areas where road de-icing
occurs chloride concentrations in stream around 3000 mg/l were recorded, studies show that
increased salt level in the environment can have deleterious on both flora and fauna of aquatic
species (Blasius 2002). Few studies have been published on the environmental impacts of salting
ski trails, with the few that have been both negative and positive environmental impacts have
been documented as mentioned in the above paragraph. The largest concern with the addition of
salts appears to be the increased chloride concentrations of ground and surface water around ski
areas.
More modern snowmaking techniques include the use of bacteria as a method to create snow. An
example of a product is called Snowmax. Snowmax is a trade name for the Pseudomonas
syringae. This bacterium naturally creates a protein that is a catalyst for ice formation. This
effectively raises the temperature at which water will freeze or nucleate. Being non pathogenic
and inactivated, snowmax does not prove to be a substantially harmful product to humans. This
is mainly because the levels of endotoxins in snow are low. (Lagriffoul et. al, 2010).
Ski Area
Water usage
millions gal/hr
gal/min
Drift
gal/day
Drift
gal/year
(4 months)
Cambridge (Smuggs)
0.33
230
0.62
521.64
Burke
0.09
63.33
0.17
142.8
Dover
(Mt. Snow)
0.06
416,6
1.12
940.8
Fayston
(Mad River)
0.13
90.0
0.22
184.8
Killington
0.82
570.0
1.54
1243.6
Ludlow (Okemo)
0.9
625.0
1.82
1528.8
Stowe
0.67
465.0
1.25
1050.0
Stratton
1.29
846.6
2.42
2032.8
Warren (Sugarbush)
0.32
221.67
0.60
504.0
Average:
739.2
Table 2. Based on 2005 USGS data. Estimated Water Withdrawals and Return Flows in Vermont
in 2005 and 2020
Drift is another effective additive for producing snow. Organo-silicone surfactant is the common
chemical name for the Drift mixture. Eighty-four percent of this mixture is composed of modified
heptamethyltrisiloxane. The Aquatrols corporation does not disclose the other sixteen percent
because it is listed as a trade secret (Aquatrols, 2009 a ). As the chemicals decrease the cohesive
properties of the water particles, the surface tension also decreases. This results in an increase in
the droplet surface area. When water is pumped out of a snow gun the droplets often collide
before they form snowflakes, creating wet snow (Burke, 2011). Decreasing the cohesion forces
allows the droplets to flatten, increasing the surface area and allowing the droplet to freeze
quicker. Because the chemical properties decrease the number of droplets forming wet snow, the
quality of the snow is more manageable for ski areas (Burke, 2011). Drift is injected into the
water at a ratio of 3:1,000,000 gallons. This means that for every million gallons of water there
are three gallons of drift (Aquatrols, 2009 a). Sugarbush resort used about 221.67 gallons of
water each minute in the 2005. This equals out to be 504 gallons of drift used every year. Table 2
shows the amount of drift that would be required for each ski resort based on the flow rate
(gallons/minute) in 2005. Although some ski resorts are larger they require less uses of drift. This
may be explained by the lower amount of water withdrawal due to the increased efficiency of the
snowmaking equipment.
According to an environmental impact summary the chemicals in Drift have a low impact threat
because they have a low toxicity and an ability to be degraded by soil particles (Borgert, 2002).
Since the chemical suppliers sponsored the tests, they were not done using high doses that would
emulate the effect of a spill. There is only limited available research on snowmaking additives, so
most of the information was gathered from distributors and speculated from the properties of
related chemical groups. Polydimethlysiloxane chemical groups are similar to the chemicals in
Drift. These groups of chemicals bond to clay particles and can be degraded by microbes
(Borgert, 2002). MSDS suggest that because of the low toxicity and high solubility, the chemicals
do not pose a threat from snow making to macroinvertebrates or humans (Borgert, 2002). The
LC50 (lethal concentration) and EC50 (effective concentration) for Drift both occur at high
concentrations. They range between 100 and 1000 parts per million (Borgert, 2002). This
concentration would occur during a spill. According to the MSDS the direct discharge in
situations such as spills should be avoided however the environmental effects of spills has not
been disclosed or studied (MSDS ). Long term effects are not expected to impact the environment
because of the chemical’s ability to be degraded by the soil. The effects of high concentrations
on ecosystems require more research.
Conclusions:
Risks from snow additives are not the only possible threat from artificial snow on streams, but the
amount of water withdrawn from local streams to produce artificial snow could also pose a
problem for aquatic life in the streams. Water used to generate snow is most often pumped from
surface water sources, mainly lakes and streams (Medalie, 2012). From the available withdrawal
data, average Vermont ski resort uses 467,800 gallons of water per day for snowmaking (Table 2)
Sugarbush ski resort uses about 380 million gallons of water a year and has snowmaking
coverage on 70 percent of its trails (Hoffman, 1994). Surface water withdrawals for snowmaking
affect stream health. “Poor water quality and stream health can devastate insect and fish
populations” (Briggs, 2000). This can cause a cascading effects on other organisms that rely on
the insect and fish populations in the stream. For examples if fish populations were to decline so
could terrestrial life that depend on the fish as food. Ski resorts however, can use man-made
ponds so they reduce their impact on rivers and surface waters.
Ski resorts that use their own man-made ponds specifically for snowmaking might be considered
a safer alternative when considering the effect on waterways. This was not examined in this
study, since all the resorts assessed withdrew water from naturally occurring lakes or streams.
However, from personal communication with Brian Fitzgerald, Streamflow Protection
Coordinator at the Vermont Agency of Natural Resources, told us that some ski resorts such as
Sugarbush, use periods of high flow in the river to fill up the retention ponds, so that in winter
when flow is low, there is water available that does not need to be withdrawn.
In order to minimize ski resort loss predicted by climate change, snowmaking will most likely
substantially increase over the next 100 years (Scott et. al, 2008). This increase in snowmaking
will lead to a higher withdrawal rate of water unless retention ponds are created to allow melted
snow to be used next season instead of drawing it through mountain tributaries. Snowmaking and
grooming increases the time that snow stays on trail due to increased density, which may cause
hydrologic issues with flow rates (Keller et. al, 2004).
Recommendations
We recommend that ski areas try and move towards sustainable practices in regards to water use,
and in house treatment. This reclaimed wastewater can be used on the mountains for artificial
snow. Swales and other storm water retention is also a good way to reduce the strain on
surrounding water sources. For example, Sugarbush is working on restoration of their nearby
brooks and streams.
Table 3. Taken from Rice Brook restoration website from EPA.org
(http://water.epa.gov/polwaste/nps/success319/vt_rice.cfm)
A restoration project was taken on by Sugarbush ski resort to restore the 1.6 mile long Rice Brook
from an impaired stream to a well functioning class B stream (Table 3). The problems associated
with the stream was a low EPT values, relatively low macroinvertebrate densities, and biotic
communities with high percentages of oligochaetes (indicating poor water quality) (EPA, 2011).
High EPT values indicate that there is a high diversity of pollution-intolerant macroinvertebrates
living in the water. Many of the issues associated with the stream were caused by stormwater
runoff, which can be attributed by excess water from snowmelt caused by artificial snow
production. Sugarbush ski resort remediated the stream by installing 29 swales (ditches on the
sides of roads that collect stormwater) in Summer 2005 (EPA, 2011). Water collected from these
swales is treated before discharge into the Mad River watershed. Yearly monitoring plans have
been established and have shown improvements in the macroinvertebrate habitat. Programs such
as Sustainable Slopes are volunteer groups that monitor the environmental plans created by ski
resorts.
Another recommendation to help mitigate the effects from several aspects of alpine skiing is the
Sustainable Slopes initiative. Sustainable Slopes is an “Environmental Charter for ski areas” that
includes management principles in several categories such as energy conservation, clean energy,
waste management, fish and wildlife, and wetland and riparian zones. Each of these categories
contains principles for sustainable slope as well as options for fulfilling the principles
(Sustainable Slopes, 2005). Although the sustainable slopes program does not hold or require ski
areas to legally follow or meet all principles, the options it provides on fulfilling the principles
would be beneficial especially in the snow making process. Building retention ponds to capture
snowmelt, reuse of wastewater, and use of soil or other materials to decrease the amount of water
needed to achieve certain terrain (jumps and half pipes) are just a few of the options (Sustainable
Slopes, 2005).
Restoration efforts and monitoring programs are only the first steps towards creating sustainable
ski slopes. Additives such as Drift and Snowmax are going to be used by ski resorts, especially
since an increase in climate change will make artificial snow more of a necessity by ski resorts.
From this assessment it has been determined the additives will not pose as a significant threat as
long as they are used at the recommended concentration. There is always a risk of large scale
spills, but we conclude it as a low risk. However, summer skiing should be limited, due to the
large amount of salts that are added to ski resorts, which can negatively affect water quality.
Acknowledgements:
Thank you to Philip Halteman and Dr. William Bowden for their assistance in completing this
project.
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