Casco Bay Generally Healthy—but Experiencing Dramatic Changes

Every five years, Casco Bay Estuary Partnership gathers and analyzes the best available data on water quality, land use, habitat coverage, and other key indicators to assess the Bay’s health. We present the findings in State of the Bay reports that share vital information used by stakeholders and decision-makers to protect and enhance the condition of the Bay.

The initial State of the Bay report in 1992 came just one year after Congress designated Casco Bay as an Estuary of National Significance, leading to establishment of the Casco Bay Estuary Project (now Partnership). Like all the reports that followed, it identified critically important resources in Casco Bay and looming challenges to the Bay’s health, providing a foundation of information for people to take action.

This report—State of Casco Bay, 6th Edition—marks nearly thirty years of science and monitoring efforts that have greatly improved understanding of the Bay and documented three decades of change. It presents findings for nineteen indicators organized in three groups: Drivers & Stressors, Condition of the Bay, and Human Connections. Together, these interrelated indicators provide a framework for understanding the causes and outcomes of change in the Bay and for implementing effective solutions.

This State of Casco Bay report focuses on nineteen indicators organized in three interrelated groups: Drivers and Stressors, Condition of the Bay, and Human Connections. Stressors like climate change and invasive species are affecting the water quality and habitats of Casco Bay, and people throughout the region are working hard to make improvements.

State of Casco Bay, 6th Edition contains several indicators that were not included in earlier State of the Bay reports. Over time, these new indicators have grown in importance, demonstrating the need for continual vigilance to detect and understand ecological dynamics in the Bay.

On the whole, Casco Bay continues to be remarkably healthy as it enters the 2020s, compared to many other U.S. estuaries, testament to the dedicated efforts of many individuals and organizations. Yet major changes are under way that warrant a timely response to protect the Bay and the many people whose livelihoods and quality of life depend on it.

We now live in a greatly altered climate that contributes to emerging global challenges such as invasive marine species, warming waters, sea level rise, and coastal acidification. Meanwhile, local issues identified decades ago like stormwater runoff, bacterial contamination of tidal flats, and barriers to migration of anadromous fish still pose major challenges.

The Dashboard of Key Findings on the next page highlights a few of the most noteworthy changes that we found in our data analysis. We encourage you to read the entire report to get a comprehensive sense of the “State of Casco Bay.”

The information contained in this report—along with the knowledge, practices, and relationships fostered through the Casco Bay Estuary Partnership over the last thirty years—enables all of us to work toward solutions that will benefit everyone who lives, works, and recreates around the Bay.

In continuing partnership,

Curtis Bohlen, Executive Director

Casco Bay Estuary Partnership