Nitrogen, a critical element in all forms of life, is continuously being passed from nonliving to living matter and then back again, but an excess of this nutrient can have adverse effects on aquatic environments. An understanding of the past, present, and future sources, movement, and fate of nitrogen in the Chesapeake Bay watershed can help inform efforts to bring this cycle back into balance (fig. OV.1).

This newsletter was created in collaboration with the Chesapeake Bay Science and Technical Advisory Committee (STAC) to summarize the rational for the STAC Rising Water Temperatures workshop.

The aim of this report card is to provide a transparent, timely, and geographically detailed assessment of 2019-2020 Coastal Bays health. Coastal Bays health is defined as the progress of four water quality indicators (total nitrogen, total phosphorus, chlorophyll a, dissolved oxygen) and two biotic indicators (seagrass, hard clams) toward scientifically derived ecological thresholds or goals.

The Darwin Harbour Integrated Report Card has been developed through extensive consultation with stakeholders from the Darwin Harbour region and relies heavily on their knowledge and expertise. Initiated by the Darwin Harbour Advisory Committee, a series of workshops were held in March 2020, representing the first step in this report card journey.

Published in 2021, the 2020 Severn River Report Card summarizes data collected in the summer of 2020. The Severn River received a C- grade in 2020. All three indicators--water clarity, dissolved oxygen, and underwater grasses--declined from 2019 to 2020. However, more samples were collected in 2020 than in 2019, so comparing the two years is not apples to apples.

Effective stewardship of ecosystems to sustain current ecological status or mitigate impacts requires nuanced understanding of how conditions have changed over time in response to anthropogenic pressures and natural variability. Detecting and appropriately characterizing changes requires accurate and flexible trend assessment methods that can be readily applied to environmental monitoring datasets. A key requirement is complete propagation of uncertainty through the analysis.

In the annual IAN Report Card, IAN staff reflect on accomplishments from 2020. The self-assessment is based on indicators in three categories: social impacts, ecological outcomes, and partner engagement. Overall, IAN received an overall grade of C (78%) which is a decrease from the 2019 score of B (84%).

Environmental monitoring programs generate multivariate time series for the assessment of ecosystem health. Recent developments in causal inference offer ways to translate these observational data into networks able to explain gains and losses in the trajectories of indicator variables. Here, we present a case study of this approach using surface water dissolved oxygen (DO) criteria attainment across the Chesapeake Bay.

In the Chesapeake Bay, excess nitrogen (N) from both landscape and atmospheric sources has for decades fueled algal growth, disrupted aquatic ecosystems, and negatively impacted coastal economies. Since the 1980s, Chesapeake Bay Program partners have worked to implement a wide range of measures across the region—from the upgrading of wastewater treatment plants to implementation of farm-level best management practices—to reduce N fluxes to the Bay.

Extensive efforts to adaptively manage nutrient pollution rely on Chesapeake Bay Program’s (Phase 6) Watershed Model, called Chesapeake Assessment Scenario Tool (CAST), which helps decision-makers plan and track implementation of Best Management Practices (BMPs). We describe mathematical characteristics of CAST and develop a constrained nonlinear BMP-subset model, software, and visualization framework.