In 2016 the Colorado health department announced the presence of cancer-causing chemicals in drinking water in Fountain, Colo., just outside Colorado Springs. Tests by the Environmental Protection Agency (EPA) discovered that nearby military bases had been leaching toxic chemicals, including substances known as PFASs, into drinking water for decades, potentially contributing to higher-than-normal rates of cancer. The Department of Defense has since admitted their responsibility for at least 55 drinking-water site contaminations worldwide, and the EPA has announced new plans to set drinking-water limits for PFASs by the end of the year.

When Americans think of polluting industries, they usually think of steel mills, coal plants and massive factories belching smoke and dumping toxins. But like the military bases in Colorado, industries not normally associated with pollution have been major drivers of environmental harm in the decades since the rise of the modern environmental movement — including Silicon Valley’s tech companies. Focusing on these stories, rather than the outdated images of smokestacks, steel factories and burning rivers, shows the persistence of pollution in a high-tech age, as well as the necessity of ongoing local activism to demand federal regulation.

Drinking-water contamination has been a source of health concerns for well over a century. Issues of water quality, sewage disposal and waste treatment rose up alongside the development of urban areas, which depend on access to fresh water for sanitation, public health and industrial and municipal development. Throughout the 19th century, American cities treated water supplies as public sewers and waste depositories. Few industries and property owners faced challenges to their use of water resources until public health advocates during the Progressive Era brought attention to the ways pollutants were contributing to health problems in local populations.

Progressive-era reforms curbed some of the worst offenses of the time, but industrial growth in the decades that followed continued to pollute the environment. Concerns over that pollution culminated in the late 1960s and early 1970s with public awareness campaigns like Earth Day, new federal regulations on water and air pollution and, in December 1970, the founding of the EPA.

The sheer number of products available to industries, farmers and households exacerbated concerns. In the 1970s, roughly 500 new chemical compounds appeared on the market each year, which had few standards or assessments in place aside from some weakly-enforced by the EPA. Compounds and chemicals thought to pose little environmental or health risk had, with their appearance in drinking water, prompted widespread concern.

Drinking water became a central concern of Congress in the early 1970s. In 1972, the EPA released a study of drinking-water supplies in New Orleans that found 36 organic chemicals and known cancer-causing compounds. An additional study of New Orleans's water supplies released in 1974 by the Environmental Defense Fund showed high incidences of cancer among people whose primary source of drinking water came from contaminated surface waters. The presence of such chemicals in various communities throughout the nation led to the passage of the Safe Drinking Water Act in 1974, which established new federal quality standards.

But this law didn’t end drinking water pollution, far from it. Nor was the pollution limited to the usual culprits that Congress intended to address with this legislation.

In the 1980s, a series of water tests throughout the San Francisco Peninsula revealed a startling finding: the widespread contamination of aquifers. The first discovery of contaminants near Fairchild Semiconductor in southern San Jose prompted further investigation, with additional tests locating over 100 contaminated drinking-water wells spoiled by high-tech manufacturing facilities. The manufacture of electrical components involved harsh chemical solvents and gases like 1,1,1 trichloroethane, xylene and methanol. Those chemicals were stored on-site in containers thought safe to hold them, but their widespread appearance in Silicon Valley’s water revealed the invisible perniciousness of high-tech pollution.

The presence of groundwater contamination in Silicon Valley in the 1980s destroyed the narrative that high-tech was a clean alternative to the industrialization of the Northeast and Midwest. But the central concern of residents now dealing with the effects of contaminated drinking water was what to do next. Local activism offered a path forward.

Activists quickly learned that lawsuits and health studies were only one part of the solution. A study by the California health department concluded that the higher rates of birth defects in San Jose could not be decisively tied to the contamination of drinking water. But skeptical residents like Lorraine Ross continued to apply pressure, suing Fairchild Semiconductor, which eventually reached a multimillion-dollar settlement with 530 residents in South San Jose.

While legal remedies were being explored, the larger issue of contamination continued to dominate headlines. Neighborhood activists, led largely by women, partnered with the new Silicon Valley Toxics Coalition (SVTC) and other local organizations to develop state and municipal right-to-know legislation. The new regulations required companies to publish what kinds of chemicals they stored on-site as well as develop new reporting and monitoring guidelines in the event of a leak.

Activists generated enough political momentum in the mid-1980s to force new regulatory measures, not only the right-to-know legislation but new city and county rules about storage containers, fire ordinances and hazardous materials monitoring. The regulations developed at the local level served as a model for state legislation around safe drinking-water standards. Proposed legislation in 1983 adopted the county ordinances, tweaking them enough that they could be applied throughout California.

Local politics also influenced federal regulations. SVTC’s proposals for monitoring, storing and regulating hazardous chemicals influenced changes to the Superfund law in the mid-1980s. House Bill 5640, co-sponsored by U.S. Rep. Norman Mineta (D-Calif.), helped redefine what was considered an “imminent hazard” and implemented stricter standards for containing possible leaks. While the bill failed in the Senate, the adoption of regulations that originated in Santa Clara into proposed federal legislation demonstrates just how central Silicon Valley’s pollution had become to anti-toxics legislation.

While local laws imposed a new regulatory apparatus on high-tech manufacturing, a federal response also arrived. Test wells drilled throughout the San Francisco Peninsula to examine the aquifer for contaminants found leaks so widespread that local governments would be unable to fully confront the problem, both in terms of costs and resources. By 1990, officials with the Environmental Protection Agency eventually declared 29 Superfund sites — more than any other county in the United States — and determined that 24 of the sites were caused by high-tech toxins. The influx of government funding and support allowed for a faster response to remediation, but the cleanup continues to this day.

Times are different today. Like the neighborhood activists of Silicon Valley, communities around the country face threats to their water supplies — not just the high-profile places like Flint, Mich., but in countless communities that have received little attention. Political pressure sometimes works, as with the Defense Department admitting to water contamination and the potential for new EPA regulations around PFASs. But sometimes it doesn’t, as the ongoing crisis in Flint sadly illustrates.

Yet local activism can influence national action. Regulatory measures, political organizing by advocacy groups and resident pressure on local and national legislators shape responses to environmental risk. Activists cannot only successfully raise awareness about the challenges communities face, but can also recast what is perceived as pollution and risk — a necessary strategy as Americans tackle the massive environmental threats of the 21st century.