Applied Sciences

Section 5.5 Water Quality

Close to Home: Assessing Local Drinking Water

The Flint water crisis began in 2014 when the city of Flint, Michigan, changed its public water sources from the Detroit River and Lake Huron to the Flint River. During the transition, the city mismanaged how it was treating its water, and pipelines began releasing large amounts of lead into the public water supply. More than 100,000 residents were exposed to high levels of this heavy metal neurotoxin, including 6,000 to 12,000 children who may suffer from lifelong health challenges as a result. A federal state of emergency was declared in 2016, and ever since, officials have been scrambling to fix the problem.

The Flint water crisis demonstrates the high stakes involved with protecting public water supplies. It also highlights the importance of regular water monitoring. In this feature box, we will learn about some regulations that protect our water supplies. We will also take a closer look at where our drinking water comes from and determine if it is safe to drink.

The SDWA of 1974 requires the mandatory monitoring of public water supplies throughout the United States. Local water authorities must test drinking water for microorganisms, disinfectants, and chemical pollutants like lead on an annual basis and publish their findings in documents called Consumer Confidence Reports (CCRs). These reports provide background information on local water systems as well as the detailed monitoring information of specific pollutants. Table 5.4 is an excerpt from a 2017 CCR for Meadville, Pennsylvania.


Table 5.4: Excerpted 2017 water test results for Meadville, Pennsylvania

Con- tami- nant

Action level MCLG

90th per- centile value Units

Sample date

# of sites above AL of total sites

Viola- tion

Sources of con- tamination

Lead 15 0 2 ppb 06/01/16 0 out of 30 sites

No Corrosion of household plumbing; ero- sion of natural deposits

Copper 1.3 1.3 0.5 ppm 06/01/16 0 out of 30 sites

No Corrosion of household plumbing; ero- sion of natural deposits; leach- ing from wood preservatives

Source: From “2017 Annual Water Quality Report,” by Meadville Area Water Authority, 2017 (https://meadvillepa _Confidence_Report.pdf).

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Section 5.6 Water Conservation and Management

5.6 Water Conservation and Management

Throughout the 20th century, the primary approach to meeting growing water needs and demand was to build more dams, reservoirs, pipelines, and water treatment plants. The basic idea was to deliver high-quality water to all end users and to eliminate wastewater. The result was a highly centralized and industrial-scale approach to meeting water demand, one that placed a large amount of political and economic power in the hands of water utilities.

Peter Gleick, a water scientist and cofounder of the Pacific Institute, has labeled this approach the hard path for water because of its focus on physical infrastructure and water supply projects. While Gleick acknowledges that hard path approaches have brought economic and health benefits over the past 100-plus years, he argues that now is the time for a new approach to water management. This new approach, a soft path for water, is meant to complement and build on the success of established hard path infrastructure. But rather than building new water supply and distribution systems, the soft path focuses on improving efficiency and helping local communities take control of their own water needs (Gleick, 2010; Pacific Institute Staff, 2013).

Close to Home: Assessing Local Drinking Water (continued)

This section of Meadville’s CCR presents the results of lead and copper monitoring. Three columns, in particular, provide important information about the safety of this drinking water. First, there is the maximum contaminant level goal (MCLG) for each pollutant. Depending on the type of pollutant being measured, these values might also be called a maximum residual disinfectant level goal (MRDLG). When pollutant levels are below these values, there is no known risk to human health.

You may also notice the column providing an action level (AL) for each pollutant. This value represents the enforceable standard for drinking water. In other words, the EPA requires water authorities to take action when measurements exceed these levels. These levels may also be listed on CCRs as maximum contaminant levels (MCLs) or a maximum residual disinfectant levels (MRDLs). In general, these values are set as close to MCLGs and MRDLGs as possible while taking technology and cost limitations into consideration.

Finally, the column labeled “# of sites above AL of total sites” tells us how many of the locations sampled by the water authority exceeded the upper limits set by the government. Luckily for the folks in Meadville, none of these sites appeared to have excessive amounts of lead or copper.

Now that you have a better understanding of what drinking water information is available and what it means, see if you can find a CCR for your location. You can often find them on the Internet by using “Consumer Confidence Report” and the name of your hometown as search terms. You can also obtain this information by reaching out to your local water authority. By reading the CCR for your hometown, you will learn a little bit more about where your water comes from and whether there are any contamination issues you should be concerned about.

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Section 5.6 Water Conservation and Management

Characteristics of the Soft Path Gleick distinguishes the soft path for water from the hard path in a few different ways. First, the soft path focuses on meeting the water-related needs of people, not just a certain level of supply. People need water to clean clothes, irrigate crops, and shower, and if we can help them find a way to do these things with less water, we should. For example, washing machines that use half the water to wash clothes or irrigation systems that require one third of the water to support crops are still allowing home owners and farmers to achieve the desired outcome at a lower cost.

Second, the soft path pays more attention to matching water quality to specific end uses. For example, water for irrigation or certain industrial uses does not have to be of the same quality as water we use for drinking or bathing. As a result, soft path approaches often involve finding ways to reuse water more than once before treating it, such as by diverting gray water—rela- tively clean water from sinks and showers—to water plants or flush toilets.

Third, the soft path emphasizes smaller, decentralized solutions to water management issues. Rather than invest massive amounts of scarce capital in new water supply systems, these funds could be used to pay for hundreds of smaller scale initiatives at the local level that save just as much or more water. For example, many water utilities promote and even make avail- able, at low cost or no cost, water-conserving devices (such as low-flow showerheads and rain barrels) and products to their customers.

Fourth, the soft path recognizes that water is as essential to the health of natural systems as it is to human society. Therefore, soft path approaches seek to work with nature rather than try- ing to engineer or work against it. This is precisely what New York City did when it invested in the water purifying ecosystems in its water supply region.

Examples of the Soft Path Soft path approaches to water management are becoming more common as opportunities to develop new water supplies dwindle and as the cost of hard path approaches continues to rise. In the 1970s Orange County, California, was one of the first locations in the United States to experiment with treated wastewater reuse. At the time, the Orange County Water District was pumping water out of its main aquifer faster than it could recharge, and as a result salt water from the nearby Pacific Ocean was seeping into the aquifer. The water district also imported water from the Colorado River and the Sierra Nevada mountain range, but that sup- ply was limited and costly. A decision was made to take municipal wastewater—the water left over after sewage is treated—and pump it into holding ponds directly above the municipal aquifer. This wastewater slowly seeps into the aquifer below, which helps maintain water lev- els and supply. Because soil can naturally filter any remaining contaminants from the water, this approach also maintains the quality of Orange County’s main aquifer. Orange County’s wastewater-to-drinking-water facility (known as the Groundwater Replenishment System) is now the world’s largest, and with an upcoming expansion scheduled to begin in late 2019, it will provide close to 500 million liters (130 million gallons) of drinking water a day and meet 40% of the district’s overall demand.

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Section 5.6 Water Conservation and Management

In addition to wastewater reuse, local water authorities are adopting other soft path approaches. For example, Los Angeles and other cities in Southern California used to try to prevent flooding by building concrete drainage channels to carry storm water straight to the ocean. Today these cities are making changes to road surfaces, city parks, and other built-up areas to slow storm water runoff and increase rates of recharge to underground aquifers. These are examples of the soft path approach of working with nature.

Cities in the eastern United States that have older water distribution systems are increasing efforts aimed at leak detection and repair. The WRI estimates that up to 50% of all the water “captured” by water supply systems in the United States is lost to evaporation, leaks, and inefficient use. Basic investments in leak detection and repair can cut these losses dramati- cally and save water districts and their customers millions of dollars. Elsewhere, especially in drought-prone regions of the Southwest, water districts are working with local residents to help them cut water use for landscaping, bathing, toilets, and other purposes (see Figure 5.8). It costs the water district less to help a customer cut water demand than it does for the water district to increase water supply.

Given that agriculture is the single biggest user of water globally, improving water use effi- ciency in this sector is an important part of the soft path approach. The most basic and inef- ficient form of crop irrigation is known as flood irrigation. This involves pumping water from a river or underground aquifer and allowing it to flow across a farm field. Likewise, spray irrigation uses large-scale sprinklers to spray large amounts of water on a field. Both methods lose as much as half the water they spread through evaporation and runoff. Far more efficient methods for crop irrigation are available and have come into wider use in recent years as farmers become more aware of water supply challenges. Low-energy, precision application sprinklers, drip irrigation systems, and center-pivot, low-pressure sprinklers all deliver 80% to 95% of the water used to the plants where they need it. Small-scale farmers in develop- ing countries are also increasingly returning to water conservation practices and approaches that were once more common. These include rainwater harvesting and the construction of simple “check dams” built across water channels to slow runoff and increase water infiltra- tion to aquifers. Even small improvements in the efficiency of water use in agriculture can go a long way to help free up water supplies for thirsty cities like Cape Town, South Africa.

Learn More: Orange County’s Soft Path Approach

More information about the innovative groundwater replenishment system in Orange County, California, can be found here.

• •

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Section 5.6 Water Conservation and Management

Figure 5.8: Water efficiency tips

Where else can you save water?

Source: Adapted from artisticco/iStock/Getty Images Plus

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Section 5.7 Forests and Water Management

Soft path approaches to meeting water demand represent a move toward integrated water resources management (IWRM). IWRM looks at issues of water supply and water demand holistically and in an integrated manner, rather than treating them as separate matters to be addressed by different agencies and organizations. What soft path approaches and IWRM have in common is that they tend to put more emphasis on local solutions to local challenges, rather than relying, for example, on the construction of new dams hundreds of miles away to meet water supply shortages. Given the increasing challenge of meeting world water needs in a time of rising populations and global climate change, such local approaches may be the best option for avoiding severe water shortages and conflict.

The final section of this chapter shifts to a focus on the role of forests and forest ecosystems in maintaining both water quantity and water quality. As we saw with the example of New York City’s water system, forested ecosystems help replenish water sources and purify water as it enters reservoirs, rivers, and streams.

5.7 Forests and Water Management

It may seem odd to have a section on forests in a chapter on water, but effective forest man- agement plays a critical role in good water management. Forests provide ecosystem functions and services that affect both water quality and water quantity. In a sense, forests are a form of natural infrastructure that can be just as important—or even more important—to water qual- ity and quantity as the physical infrastructure of dams, pipelines, and water treatment plants.

Maintaining Water Quantity As rains fall and snow melts, forests help slow the rate at which water runs off the surface. Tree roots and dead branches and leaves on the ground intercept water and hold it, allowing it to slowly seep into the ground. Some of this water recharges underground aquifers, while the rest is slowly released into nearby streams and riv- ers. Experiments at the Hubbard Brook Experimen- tal Forest in New Hampshire and at other locations have been designed to measure what happens to stream flow when forests are cleared (Franz, 2016). In one experiment after another, water runoff and stream flow increased dramatically after trees were removed, resulting in a stream flow pattern that spikes immediately after rains or snow melt (increasing the risk of floods) and then drops dra- matically soon after. In contrast, when forests are intact, water from rains and snow melt is released slowly to underground aquifers and nearby streams, and stream flow patterns are more steady and reli- able. In fact, it’s typically the case that even after weeks of no rain or precipitation, forest streams are still flowing with significant volumes of water.

iStock/Thinkstock Cleared forest land—such as the deforestation in the Amazon shown here—can create sediment loading in nearby streams and rivers, creating water-quality issues for communities farther downstream.

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Section 5.7 Forests and Water Management

Maintaining Water Quality In addition to maintaining water quantity, forests also help maintain water quality. The Hub- bard Brook experiments have shown that water running off cleared forest land is high in nitrates and other pollutants and does not meet clean drinking water standards. Clearing for- ests also increases soil erosion and “sediment-loading” of streams and rivers, increasing the costs of water treatment for downstream communities. In contrast, intact forests help pre- vent soil erosion and can also help trap and hold other pollutants and contaminants before they can enter nearby waters. This is why riparian buffers—discussed in Section 5.5—are so important to water quality.

The example of New York City’s water system at the start of this chapter helps illustrate the importance of forests in good water management. Another example comes from Rio de Janeiro in Brazil, site of the 2016 Summer Olympics. Rio operates the world’s largest water treatment plant to provide clean water to its 6.3 million residents. However, this treatment facility is facing operating challenges due to deforestation that is occurring upstream from the city. The deforestation is increasing rates of soil erosion and leading to increased sediment in the water as it reaches Rio’s reservoirs. Like New York, Rio is approaching this challenge not by constructing more or better water treatment plants but by going to the source of the problem in upstream watersheds. The strategy is to restore and maintain upstream forested areas, an approach that will save the city an estimated $79 million in water treatment costs annually while also improving water quality (Ozment & Feltran-Barbieri, 2018).

Maintaining the Global Water Cycle In addition to their direct and immediate impact on water quality and quantity in nearby eco- systems, we are also becoming more aware of the critical role that forests play in maintaining the global water cycle. Trees and other plants perform the ecosystem service of drawing water from the soil and releasing it to the atmosphere as water vapor through transpiration. This process has been summed up beautifully by environmental journalist Fred Pearce (2018a):

Every tree in the forest is a fountain, sucking water out of the ground through its roots and releasing water vapor into the atmosphere through pores in its foli- age. In their billions, they create giant rivers of water in the air—rivers that form clouds and create rainfall hundreds or even thousands of miles away. (para. 1)

Those “giant rivers of water in the air” are disrupted through deforestation, especially large- scale tropical deforestation. Deforestation in the Amazon basin could disrupt precipitation patterns and agriculture in China and central Asia thousands of miles away.

As a result, any discussion of effective and sustainable water management should also include ideas for sustainable forest management. In forested, tropical regions of South America, Africa, and Southeast Asia, this often involves efforts at community-based forest manage- ment. Rather than fencing off forests as a means of protecting them, these programs work with local communities to help them derive a livelihood from the forests while also managing them sustainably. Rain forest–certified coffee, chocolate, and other products are examples of items that can be produced in a way that maintains the ecological integrity and ecosystem services of forested regions.

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