Drought versus El Niño: The Effects of Water in Dry and Wet Times
By Terry Arko
The capabilities of our water
Water is an amazing, mysterious and powerful element. To understand the capabilities of water and its effect on our environment, it is vital to understand how water travels throughout our world. The water cycle is a continuous loop of various methods of which water continuously transforms and renews itself. Water leaves plants and enters the atmosphere through a process known as transpiration. From bodies of water and the ocean, water travels back to the air through evaporation. Even humans give water back to the atmosphere, through perspiration and condensation from our breath. Water then falls back to the earth in the form of rain, hail, sleet or snow.
Water is fascinating in that it is the only liquid on earth that can exist in three forms: vapor, solid or liquid. When you see fog while driving to work, you are seeing water in one form, traveling into the atmosphere. As water transforms and travels, it is subject to the environment through which it passes. Fog, for example, rises up from the ground and passes through the surrounding air. As it does so it picks up whatever is in the air, whether it be smoke, dust or car exhaust.
Snow on the ground can pick up contaminants and bacteria. When the snow melts and turns into liquid, those contaminants and bacteria can be transported into nearby streams and rivers and possibly end up in source water. In Milwaukee, WI in 1993, one of the largest outbreaks of Cryptosporidium in drinking water was found to be the result of contaminated snow melt feeding into Lake Michigan.
Water moves about this world in lakes, rivers and even underground. It is the great absorber and transporter of whatever comes in contact with it. In today’s world, we are faced with extreme droughts and unusually heavy rainstorms. Both create many challenges to source water that can also have detrimental effects on the surrounding environment.
The evaporation problem
Some studies suggest that the annual evaporation rate in southern California ranges from six to eight feet (1.82 to 2.43 meters). That means the entire contents of an average backyard swimming pool can be removed by evaporation in a year. Only pure water vaporizes in the process of evaporation. So, as pure water evaporates, it also leaves behind more dissolved solids that contribute to an increase in TDS in swimming pools, lakes, ponds and other source waters.
There are two environmental factors that will increase the acceleration of evaporation: temperature and humidity. If you place a pot of water on a table in a cool and humid environment, it can take weeks to months for the water to evaporate. If you place that same pot on the stove and turn on the heat, however, it will evaporate in a matter of minutes. The more heat, the faster evaporation occurs. Also, when you combine heat with dry air, water will vaporize more quickly. This is why evaporation is a big problem during times of drought, when the air is warmer and drier. It’s also why people get thirstier faster in Phoenix, AZ than in Portland, OR.
The accelerated evaporation during times of drought means that the build up of solids in water sources will also increase, leading to higher TDS, calcium hardness and pH in water. The increase of pH in lakes results where evaporation is the main water outlet. As these lakes dry up from evaporation, the saturation of contaminants and nutrients becomes greater due to the lack of fresh water dilution. One example of this is Soap Lake in Washington State. A high nutrient content in lakes can lead to accelerated growth of algae. The increase of photosynthesis for algae growth can also cause a rise in the pH of the water. As lakes become shallower, surface algae blocks the light to the algae below. The algae below the surface dies off and in the process, dissolved oxygen levels are reduced. This then leads to aquatic life dying off. The lake then could end up as a lifeless dry bed. During these stages, the quality of water obviously suffers and becomes more difficult to treat for human consumption. One solution for lakes with heavy nutrient levels is to pump oxygen into them. This helps in two ways, by increasing dissolved oxygen levels and causing the phosphates to remain in the sediment. The State of Washington Department of Ecology recommends the pumping of oxygen or using aeration because when sediments lack oxygen in nutrient-rich waters, conditions can exist to release more phosphorous into the water. In swimming pools, chemical oxidation can be applied or water falls or fountains can be utilized. Also, chemical-based phosphate removers are practical in backyard swimming pools.
Lower water levels
Another challenge during drought times is that groundwater gets used up more quickly. Groundwater is what comes from rain that permeates through the soil and then makes its way below ground through cracks and fissures. Groundwater collects in areas underground known as aquifers. With a lack of rain and no snow pack to replenish the aquifers, groundwater can become consumed very quickly. This can be critical in agricultural areas. The contaminants in the deep source water can lead to higher total hardness, minerals and metals. According to the National Groundwater Association (NGWA), about 44 percent of the US population gets its drinking water from groundwater.
The concentration of metals such as copper and iron increase in deep groundwater. Also as groundwater levels drop, chloride levels go up from an influx of brackish water. This leads to more particulate, higher dissolved solids and taste issues with drinking water. Nitrates can be a big problem in groundwater as well, particularly in agricultural areas. Increased nitrates can have a direct effect on water disinfection. Additionally, nitrates at levels above 10 ppm in drinking water can cause a blood disorder in children under the age of six months. There are filters available for removal of nitrates from drinking water as well as RO, ion exchange and distillation systems.
Nitrates in swimming pool water can create chlorine demand that devours free available chlorine (FAC) levels and can lead to a build up of bacteria and algae. The most effective way to remove nitrates in a swimming pool is draining and diluting out a portion of the water. Draining pools in a time of drought could be forbidden, so an alternative would be to use a chemical oxidizer repeatedly until a drop in nitrates is seen. There are also portable RO trailers available to clean up dissolved solids such as nitrates.
Changing make-up water
In today’s world, where water is being imported and exported all over, it is possible to have the source water make-up change within hours. In some areas water is trucked or transported through pipes and canals from hundreds of miles away where the pH, total alkalinity and calcium hardness can be drastically different from the local water supply.
Recently in the East Bay area of northern California, customers began to notice a different odor and taste to their tap water. Complaints began to mount and so the water municipality responded by letting customers know that due to the severe drought, they needed to bring additional water in from the Sierra Nevada mountains to supplement their current supply. Because the water was warmer and subject to more sunlight, it contained more algae that gave it a musty taste and odor.
How fires affect water
Ash from forest fires can be high in nutrients such as nitrates and phosphates. One of the main firefighting chemicals dropped from planes contains compounds of phosphate and so will increase phosphates in waterways over time. Wildfires are a serious danger during times of drought when grasses, plants and foliage are dried out. Increased evaporation leads to less soil moisture, which leads to greater ground erosion, an influx of invasive plant species and the spread of pathogens in the soil. These dry drought conditions create a perfect environment in forests for insects (like bark beetles) to invade and decimate trees—dead and drying, these trees become the perfect tinder for fires. This was one of the major conditions that caused wild fires in the mountains of California. In 2015, northern California experienced one the worst wildfire seasons in history. Three major fires were raging simultaneously and a total of 283,000 acres were burned. After one of the largest wildfires in San Diego, California in 2008, pool service professionals in the area who routinely test water for phosphates saw a large spike in levels in the swimming pools.
What’s in rain?
Unlike what we may think, rainwater is not pure. In fact, water is incapable of condensing into droplets without the presence of dust, smoke or other impurities in the atmosphere. A cloud of water droplets can only form in the presence of impurities. Water is a natural filter for anything that is in the air. In the city of Seattle, they say there is no problem with air pollution because they take the air pollution and turn it into water pollution. Those raindrops splashing on the roof of a car are bringing with them organic and inorganic substances, bacteria and nitrogenous compounds of minerals and metals. It is very typical after a heavy rain for algae to become a problem in lakes, ponds and backyard pools. This is because the rain itself can bring an increase in the levels of nitrates, which are a known food source for algae.
Acid rain is a phenomenon created as a result of pollution in our atmosphere. In the dry season, there can be a build-up of nitrogen and sulfur compounds in the air from automobile and industrial emissions. When the moisture from rain or fog combines with these compounds in the atmosphere, the result is nitric and sulfuric acids. When acid rain enters water, it will have an immediate effect on lowering the pH that can lead to a harmful result on the aquatic life in the water. If backyard swimming pools are not properly balanced with a good buffering capacity of total alkalinity, then acid rain can cause pH levels to plummet.
The hidden dangers of flood water
There are several types of flooding that can occur. Flash floods are the result of a break in a levee or dam or heavy rains in mountain areas above a flood plain. This can be very destructive and cause contaminated water to rush in quickly, overwhelming low-lying areas. In coastal regions, storm surges and high tides can cause flooding. (When Hurricane Sandy hit the coast of New Jersey, there were many pool service pros who reported finding live shrimp in their pools after the flood waters receded.)
Flood waters will contain mud, silt, organic materials and very possibly, raw sewage that is loaded with bacteria. If flood water overwhelms the infrastructure of a community drinking water system, tap water may be unfit to drink. Flood water can also carry chemical contamination from local industries. One may also expect an influx of nitrates and phosphates from flood waters, particularly in agricultural areas or in areas of phosphate mining, such as parts of Florida. Flood water can also contaminate gardens. Vegetables from a garden that has been under flood water should not be consumed, as they may contain pathogenic bacteria that can cause gastrointestinal illness.
The damaging effects of flood waters can carry on long after the waters have receded. One of the biggest problems in homes or businesses can be controlling the growth of mold on surfaces or areas that were once under water. Many professional agencies exist that have experience in cleaning up homes or industrial buildings after flooding; it is advisable to contact them, especially if dealing with problems of mold growth.
Contaminants from construction sites
Large-scale construction sites can be a major contributor of pollution to surrounding waterways during times of heavy rains or flooding. This can include an influx of silt, adhesives, cements and solvents. In 2007, the Port of Seattle completed a third runway at the very busy SeaTac International Airport. During construction, there was concern that when the rains came, much of the debris from the project would end up in nearby streams and have an adverse effect on the aquatic life. Besides building retaining walls around the site, the port also incorporated a sophisticated system of filters. Prior to filtration, the project water was treated with a marine biopolymer that caused small micron particles to form filterable flocs that could be removed by sand filters. The result upon testing was that the water going back into the environment was cleaner than the stream water.
There is no denying that weather patterns are changing and in certain areas water itself has become a big challenge. Being aware of our environmental water during extreme times can help. Much of the southwestern US has seen a drought unlike anything in over 500 years. Groundwater levels have sunk to catastrophic levels and regulators have imposed strict conservation laws in reaction to this. In California, recent El Niño storms and the snow pack in the Sierra Nevada mountains are bringing some hope. But experts warn it will take years to replenish what the drought has taken. Conserving water use by reducing yard watering, planting drought-tolerant plants, as well as installing low-flow toilets and water-saving shower heads can be a household solution. Also, if there is a backyard pool, keep it covered with a solid cover or the use a liquid chemical cover.
When the rains of El Niño begin to move in, it is important to make sure we are prepared with emergency generators, first aid supplies, food and lots of fresh drinking water. Have sandbags ready to protect the home, yard and swimming pool from floodwater. We can’t always predict the weather but we can be prepared to deal with the effects of a changing climate on our greatest resource: water.
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About the author
Terry Arko has over 30 years of experience in the swimming pool and spa industry, working in service, repair, retail sales, chemical manufacturing, customer service, sales and product development. A certified pool operator (CPO) and CPO Instructor through the National Swimming Pool Foundation (NSPF), he is currently a Water Specialist for SeaKlear Pool and Spa Products. Arko can be reached at email@example.com.