This year marks the 50th anniversary of a transformational

turning point for Bay water quality: passage of the Federal

Water Pollution Control Act Amendments of 1972, commonly

known as the Clean Water Act (CWA).

On the occasion of this momentous milestone, this edition of

The Pulse of the Bay includes nine

perspectives written by representatives of the groups

that have a prominent role in managing Bay water quality,

and profiles of the parameters that have been the main water quality

concerns over the past 50 years, with a focus on long-term

trends and a historical perspective.

The CWA provided a legal framework and a considerable amount of federal

funding (over $1 billion, equivalent to approximately $7

billion in 2022 dollars) that drove a rapid and remarkable

improvement in Bay water quality. By 1987, all municipal

wastewater treatment plants but one were providing

secondary treatment, which effectively removes oxygen demanding

organic matter and bacteria as well as many

toxic metals and organic chemicals. Bay monitoring data

available for the 1970s and 1980s show that dissolved oxygen

levels increased, and bacteria and toxic metal concentrations

sharply declined. By 1982, public harvesting of shellfish in

San Mateo County was approved for the first time in 50

years. By 1987, the Water Board concluded that swimming

was safe in most areas of the Bay during summer.