Goodbye to Tea in Boston by Robert Zimmerman, Jr. Using a watershed-level approach to planning is well-accepted today, but often there is continued reliance on planning models that fall far short of understanding the complex interactions between wet weather, groundwater, and water infrastructure at a watershed scale. Urban stormwater runoff is widely understood to cause human health risks and damage rivers and streams, yet its disruptive effects on the natural surface-groundwater relationship and on river health are seldom acknowledged. Nor are the costs to municipal service providers and risks to human health being adequately recognized. Nearly 60% of Americans get their drinking water from groundwater stores, and their drinking water supplies are drying up. At the same time that population growth and high per capita water consumption depletes underground aquifers and surface waterbodies, groundwater and surface water sources are not being replenished at their historic rates. Even regions with more than 40 in. (1143 mm) of average rainfall per year are facing shortages. This is further evidence of the urban infrastructure “plumbing” problem: stormwater is dumped into rivers and lakes far from where it fell to the ground, with little infiltration into local aquifers; at the same time, water is withdrawn from one place, used, and sent via sewer pipes to a treatment plant that discharges the effluent into waters usually many miles away from the original source. All of this occurs in amounts and timing that is completely unnatural and damaging for rivers and other costly infrastructure, such as roads, bridges, and recreation facilities. Urban infrastructure impacts in the watershed have become an even more pressing issue as climate change has resulted in more frequent severe storms. Over the last century, the portion of the nation experiencing storms of more than 2 in. of precipitation in less than 24 hours each year has increased 20%, according to the U.S. Environmental Protection Agency. Increasingly, these storm events exceed the capacity of huge combined sewer systems even as they come on-line, escalating damage to property and river ecosystems. The Charles River Watershed Association (CRWA; Auburndale, Mass.), a non-profit advocacy organization, was founded in 1965 to serve the greater Boston metropolitan area, has faced all these issues in one form or another. It has been involved in the transformation of the Charles River, which runs east to west from Hopkinton-Newton, Mass. to the Boston Harbor, from one of the nation’s most polluted rivers to one that currently hosts some of the most intense recreational use of any river in the United States. By 1993, it became clear to CRWA that further progress in cleaning up the Charles would take more than just advocacy. Typical in the conclusions of the myriad environmental impact reports was the notion that any effects from further development along the Charles River were the result of all other uses along the river. According to these studies, the impacts of combined sewer overflows (CSOs) along a 9-mi (14.5-km) reach, an industrial park along a 1000-ft (305-m) reach, new shopping malls along reaches of 100 to 2000ft (30 to 610 m), or residential developments, simply paled in comparison. At CRWA, this is called, “death by 1000 studies.” The general attitude seemed to be, “Until everybody else cleans up this mess, mine is justified.” Additionally, there was a sense that the river was dirty and would remain dirty, regardless of any single organization’s efforts. That belief led to a slew of “bang for the buck” arguments. The logic, argued in the headwaters of the river as well as the lower basin, was that expenses associated with cleaning up any single source were excessive because, regardless of these efforts, the river would never meet standards. It was difficult to argue against this logic. The science didn’t exist, and in the political climate of the early 1990’s, spending millions to achieve essentially nothing according to standards was difficult to defend. As a consequence, CRWA started its own analysis of the river and its watershed in 1994 to answer the simple question, “How does the watershed work?” The organization raised the funds to develop a proposal to begin a 5-year analysis of the entire river, its sources of pollution, links to groundwater, and surface runoff and pollution. By establishing 37 monitoring sites along the 80 mi (129-km) length of the river, CRWA has been able to take the river’s water chemistry and flow pulse in both dry and wet weather. Each summer, CRWA examines water chemistry and flow in both dry and wet weather in the 10 largest tributaries to the river. By 1996, it built its own lab to test 17 aspects of water chemistry, including bacteria, nutrients, and anions. Staff was added in biology, hydrology, chemistry, geology, land use and civil, environmental, and agricultural engineering. Computer modeling and computer mapping capabilities were developed. In short, the organization became a nonprofit consultant with a single client, the Charles River and its tributaries. CRWA’s rapid technical growth since 1994 has led to remarkable changes in its relationships with government, municipalities, and corporations. It no longer speculates on the causes of the problems, it investigates them. It no longer accepts regulations and permitting policies as written, it works with government to make the regulations and policies more applicable to the issues that affect sustainability and the quality of the rover, its tributaries, and its aquifers. Improvements to the Boston metropolitan environment have continued apace. Point Sources
In 1993, point sources of pollution to the Charles River were deemed a thing of the past. Regulations like the Clean Water Act and the Massachusetts Water Management Act rendered them illegal, and, as a consequence, presumably gone. CRWA’s monitoring revealed, however, that thought the laws are effective, without constant vigilance, point sources persist. The New England regional EPA office, working closely with CRWA, used the organization’s monitoring data to identify bacterial problems in the river and take enforcement action. Most cities and towns cooperated with the EPA’s efforts, and the results have been encouraging. Centralized Systems Part of the Problem Massachusetts, like most of the country, favors large regional centralized wastewater treatment systems. The process for identifying new public water supplies is not coupled to impacts on aquifers, waste treatment, and sustainability of watershed health. The pressure to sewer communities has increased since 1995, when the Massachusetts Title V Septic System regulations began the inspection of septic systems prior to a house title transfer. Homeowner fear of the costs associated with upgrading septic systems has only increased the demand for regional sewers in suburban towns. In its March 2001 Infiltration/Inflow Task Force Report, the Massachusetts Water Resources Authority (MWRA), among the largest water and wastewater authorities in the United States, discussed the impacts of operating a 43-community urban wastewater collection system. During a year of normal rainfall (typically 45 in., or 1143 mm), the MWRA Deer Island Treatment Works treat 380 mgd (1.4 million m3/d) of “wastewater.” That is, of this total, 180 mgd (681 300 m3/d) is groundwater infiltrated into the wastewater collection system, and 50 mgd (189 250 m3/d) is rainwater runoff. Sixty percent, then, of the water treated at Deer Island is potable groundwater or potential groundwater recharge. Infiltration alone, taken on an annual basis, represents one-third the annual flow of the Charles, Fore, Mystic, and Neponset Rivers (the tributaries to Boston Harbor) combined. The unintended result is massive depletion of ground wells, higher costs to unnecessarily treat potable water, and severe ecological harm to rivers. In fact, it is low-base instream flow in rivers and tributaries that is the first sign of real problems in the rainwater-to-groundwater cycle. Long before drinking water wells are stressed, the ecological damage is measurable by reduced habitat, increased water temperatures, concentration of pollutants, and rapid weed growth. Regional wastewater treatment dewaters the regions it treats, contributing to drought-level instream flow during late spring, summer, and early fall, where, in the Charles River watershed, between 60% and 65% of instream flow typically comes from groundwater recharge. Centralized treatment contributes to the likelihood that communities dependent on groundwater stores for water supplies will face increasingly severe water shortages during these months over the coming decade, even in wet years. This phenomenon is already a problem in eastern Massachusetts and throughout the Northeast. It is becoming an issue in the Midwest, Northwest, and Southeast, and has been an issue in the Southwest for decades. Water
Shortage in Franklin Franklin, Mass., the state’s fastest growing community for nearly two decades, was selected by CRWA to represent urbanizing metropolitan areas. Since 1985, the city has grown from approximately 15 000 to nearly 30 000. City plans anticipate growth to 40 000 by 2015. CRWA, expecting that water resources were being taxed, was surprised to discover that, given then-current planning, the city would run out of groundwater drinking water supplies before 2015. This shortage would be caused by a lack of aquifer recharge due to accelerated runoff from paved and impervious surfaces, increased demand on aquifers for supply water, sewers extended to serve 80% of the city, and infiltration of potable groundwater through pipe failures so that water once recharged through septic systems or open space would be lost to regional wastewater treatment. The aquifer that Franklin depends on for drinking water also supplies the neighboring towns of Medway, Millis, and Norfolk. If pursued, Franklin’s growth, demand for water, and sewer expansion would cause serious sustainability problems for these neighboring communities. The consequences for the Charles River, its tributaries, wetlands, and ecosystem would be incalculable. CRWA recognized that the accepted problems of CSOs, stormwater pollution, and low base instream flow in urban Boston were in fact only symptoms. The fundamental problem in urban and suburban ecosystems really is the engineering environment that treats rainwater as a liability, disconnects rainwater from groundwater with impervious surfaces, and transports locally drawn potable water to distant locations for treatment and discharge CRWA’s subsequent work on open space and stormwater remediation projects in Bellingham, Norfolk, Medfield, and Blackstone indicated water shortages and the concomitant tributary and Charles River impacts were not unique. In fact, most urban and suburban Northeast areas face exactly the same problem, with perhaps a longer grace period than Franklin’s before the situation becomes critical. Using the U.S. Geological Survey groundwater model MODFLOW and EPA’s surface hydrology model HSP-F, CRWA began an assessment of aquifer sustainability and instream flow in Franklin. It assessed, among other things, instream flow, well drawdown, and surface water runoff from paved and constructed surfaces. How water resources and sustainability were affected became clear after CRWA used Massachusetts Department of Environmental Management statistics on residential and industrial demand, calculated additional demands associated with expected growth, and incorporated the average volume of wastewater treated at Franklin’s wastewater treatment facility. Using annual water budgets as a basis, Franklin should suffer no shortages. Unfortunately, once leaf-out occurs, recharge to aquifers virtually ends, and both environmental resources and public wells are dependant on the same finite supply of groundwater stores. The first effects are found in tributaries, where even after wet winters and heavy snowpack, the streams drop to drought conditions in mid to late April. The same is true of the Charles mainstem no later than early May. In effect, the river system is sending out a warning that the human population has engineered a system that cannot be sustained. Changing the
Outcome There are some fairly straightforward solutions to
reverse this situation facing most of the country’s watersheds: · Decentralize wastewater treatment using a number of new technologies, from denitrified land application of wastewater to greenhouse and package plant wastewater treatment, where treated water is recharged to groundwater. · Employ practices to slow and clean stormwater, and reintroduce it as recharge to groundwater, in effect re-establishing the link between rainfall and groundwater, and enhancing summertime aquifer storage. · Demand-manage water supplies by reducing the need for water supply like using xeriscaping in landscaping design and encouraging the use of low-flow appliances in homes and businesses. · Create methods of storing rainwater for use in everyday applications so that rainwater is used for irrigation and then released to groundwater, rather than lost as runoff. · Control and plan development to minimize impervious surfaces and maximize recharge and groundwater flows to rivers. CRWA is continuing to work in a number of these areas. On the campus of Boston University, CRWA has identified four sites to demonstrate stormwater remediation, where it is testing best management practices pre- and post-construction. In Bellingham, Mass., CRWA is working with town officials and American National Power Inc. to create a conservation and stormwater remediation program that will dramatically enhance groundwater storage. In Bellingham, Franklin, and Blackstone, the organization is working with community leaders to reassess methods of treating wastewater, looking at innovative technologies to clean wastewater and then recharge it to groundwater. In Medfield, it hasworked with local officials and open space advocates to identify remaining open space areas that provide recharge directly to the aquifers, and tagged them as priority areas for acquisition and protection from development. CRWA hopes that these efforts will, in the coming few years, lead to a small revolution in the way people view water, their water supply, and its sustainability. These changes also are expected to lead to changes in the way humans store and use water, and to infrastructural changes in the way municipalities use fresh water supplies and treat wastewater. We cannot continue to pretend that stormwater, public water supply, wastewater, low base flows, combined sewer overflows, transportation infrastructure, and community growth are all disconnected problems requiring separate and unique regulation and resolutions. CRWA’s work demonstrates that all are intimately connected through infrastructure development, and that we ignore the connections at our peril. |