Publications

The Chesapeake Bay Program (CBP) has used its modeling system as a planning tool to inform strategic management decisions and adaptation toward Bay restoration since the 1980s. This modeling system has been continually updated with improvements and advancements intended to keep pace with emerging science. However, it has been more than a decade since the Chesapeake Bay Program’s Scientific and Technical Advisory Committee (STAC) convened a dedicated workshop to discuss future directions for the suite of modeling tools used by the CBP. Given developments over the past twelve years (since the previous model visioning workshop), and the completion of the 2017 Mid-point Assessment of the EPA’s Total Maximum Daily Load regulatory process, STAC agreed that 2018 was an appropriate time to convene a workshop aimed at formulating a vision for future CBP modeling to guide the partnership into the future (i.e., from 2025 and beyond).

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The Scientific and Technical Advisory Committee (STAC) of the Chesapeake Bay Program (CBP) sponsored and convened a workshop on Legacy Sediment in Annapolis, MD on April 24-25, 2017. This workshop was developed in response to a request from the Chesapeake Bay Commission (CBC) with the primary goal of reviewing our collective understanding of “legacy” sediment and its relative influence on habitat and water quality, both locally and across the Chesapeake Bay, as well as the relative merits of different management approaches. This is a complex topic with important implications for Chesapeake Bay and speakers were invited to ensure a broad and comprehensive assessment of the relevant issues. As articulated by CBC Executive Director Ann Swanson, “A STAC workshop, with presentations from various points of view and a free and rigorous scientific debate, would greatly assist policymakers in understanding how “legacy” sediments fit within a suite of management activities to reduce nutrient and sediment loads to the Chesapeake Bay.”

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This report provides a summary of the proceedings of a STAC-sponsored workshop that explored market-based approaches for multifunctional buffers to identify means of accelerating riparian buffer plantings in the Bay watershed. This report also outlines specific recommendations identified by participants at the two-day workshop convened November 13-14, 2018 in Harrisburg, Pennsylvania.

This workshop focused on scalable solutions to promote implementation of multifunctional riparian buffers with the objective to accelerate the rate of buffer plantings in Pennsylvania and the greater Chesapeake Bay Watershed. This workshop brought together academics, government officials, industry professionals, and farmers to discuss potential solutions to overcome barriers to success for each buffer market-based opportunity.

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This report provides a summary of the proceedings of a Science and Technical Advisory Committee (STAC) sponsored workshop on targeting advanced best management practices to benefit shallow water resources and explore potential refinements to the current CBP model segmentation strategy. This report also outlines specific recommendations identified by participants at the 2-day workshop, held in Frederick, Maryland on May 23-24, 2018.
This workshop provided an opportunity to evaluate whether the “triblet” concept (natural channels draining to tributaries along the transition zone connecting uplands to coastal waters and functioning as bioreactors) provides a useful basis for informing watershed management and advancing coastal research. Participants were varied in expertise, including watershed hydrology, estuarine circulation, biogeochemistry, and behavioral-economics. A significant portion of the workshop was dedicated to sharing insights to understand the role of triblets as bioreactors affecting the exchange between upland and coastal waters. Participants collaborated to identify key information gaps and research opportunities to advance Bay restoration.
Lessons learned and major findings from the workshop focused on the science gaps, as well as improvements to the Bay Program’s modeling strategy.

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The Chesapeake Bay Total Maximum Daily Load (TMDL) sets goals for total nitrogen (TN), total phosphorus (TP), and total sediment reduction by political jurisdiction and by river basin in order to restore aquatic habitat. However, using total nitrogen and phosphorus rather than specific species of these nutrients, can mask processes that ultimately determine restoration success in terms of supporting fish communities and human safety, among other outcomes. For example, in some areas of the Chesapeake Bay Watershed, the proportion of phosphorus entering in a bio-available dissolved form (ortho P) is increasing, despite or even as a side effect of management efforts. A growing body of scientific evidence indicates that the speciation of nutrients influences algal biomass and the extent of hypoxia, which are reflected in water quality standards. Yet nutrient species effects are not factored into targeting TMDL effort nor the crediting system that tracks progress of jurisdictions towards their goals.

The consideration of nutrient species within the Chesapeake Bay TMDL and the broader management strategies of the Chesapeake Bay Program (CBP) would likely increase the efficiency of management by targeting effort to the nutrient species most responsible for hypoxia. For example, practices that reduce nitrate delivered to the Bay are likely more effective in reducing hypoxia than practices that reduce organic nitrogen, the latter likely being more effective in reducing harmful algal blooms. Additionally, achieving water quality goals within freshwater rivers, lakes, and reservoirs may require different reductions of nutrient species and timing of delivery. Management plans might better address multiple endpoints at a reduced cost, if these relationships were understood and made part of the management evaluation structure.

Calculations similar to those proposed have already been estimated and reflect geographic differences of nutrient loads in terms of hypoxia effects. Loads of N and P generated from different locations were converted into the common currency of “eutrophying units” to support the exchange of N and P reductions requested by some jurisdictions. A similar system to incorporate how nutrient species affect ecological outcomes could use the same concept of eutrophying units but has substantial information needs. Synthesis of existing science and new research or expert judgement to fill data gaps are required to build an understanding of the relative magnitude of speciation effects on hypoxia. Such effects must be considered under heterogeneity of nutrient inputs, land use, watershed physical characteristics, stream processes, and water body biogeochemistry. In addition, the ability of management practices to reduce specific nutrient species is understood for some, but not all, practices.

Movement toward a system that incorporates nutrient species is critical to successfully achieving the TMDL goals. In many areas of the Chesapeake Bay watershed, total nutrients are declining while bioavailable forms that contribute the most to hypoxia are increasing. These trends suggest that some waterways may not respond as expected to achieving the total nutrient cap. Synthesizing what is known about bioavailable forms of nutrients has the potential to improve the CBP’s ability to quantify effects of management efforts under a variety of conditions to ensure efforts are ultimately effective at restoring water bodies.

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As the Chesapeake Bay Program (CBP) passes the mid-point assessment, major point source discharges will have achieved (or nearly achieved) their final Total Maximum Daily Load (TMDL) nitrogen (N) and phosphorus (P) waste load allocations. Jurisdictions, however, still need to achieve substantial nutrient and sediment reductions from agricultural and urban nonpoint sources (NPS). Based on current understanding and modeling, the CBP estimates that agriculture and urban NPS need to achieve an additional 35 million and 12 million pounds of reductions, 1.3 and 0.6 million pounds of P reductions, and 941 and 594 million pounds of sediment, respectively to meet TMDL goals. State and local governments are poised to spend hundreds of millions of additional dollars to meet these goals, primarily by installing agricultural and urban nonpoint source best management practices (BMPs). Thus, BMP implementation stands at the center of CBP efforts to meet TMDL requirements. Yet, water quality monitoring suggests that the link between BMP implementation and load reductions is tenuous. In a recent STAC review, Keisman et al (2018) state “current research suggests that the estimated effects of conservation practices have not been linked to water quality improvements in most streams.” The Chesapeake Bay Watershed Model estimates substantial reductions in NPS loads, but monitoring data suggests little to no change in these loads between 1992-2012 (Keisman et al, 2018). A critical question is why? Potential explanatory factors include inadequate BMP coverage, poor implementation/maintenance, lag times between implementation and pollutant load reductions, pollutant transport and transformation processes that are incompletely understood, and inability to target BMPs to critical pollutant source areas. The purpose of this workshop was to make recommendations as to how the CBP can develop and integrate mechanisms to target BMPs to areas of the watershed producing disproportionate nutrient and sediment loads.

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A wide range of contaminants of agricultural, human, and industrial origin have degraded water quality, and pose a threat to the health of fish and wildlife populations, in the Chesapeake Bay and its watershed. A May 2019 STAC workshop brought together researchers and water quality managers working in urban and agricultural settings to synthesize the current knowledge on contaminants of concern and discuss opportunities for their reduction.

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Freshwater mussels were chosen as a focus for this workshop to consider ecosystem services, document biodiversity, outline intersections with Chesapeake Bay issues and to explore their potential to engage partners. The workshop brought diverse expertise together from across the watershed including mussel biologists, nutrient dynamics experts and water quality managers to provide recommendations which are summarized in this report.

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The Chesapeake Bay Program Climate Change Modeling 2.0 workshop was held in late 2018 to give guidance and expert advice on the models and the assessment framework used to assess the effect of climate change on the TMDL. Scientists and managers developed recommendations that could be implemented to support assignment of any additional load reductions in 2021 and made recommendations on longer-term modeling goals for the partnership. Although a full workshop report is only now being published, several recommendations on near-term model revisions have already been implemented and have supported policy decisions made by the CBP Principals Staff Committee. The longer-term model revisions recommended here will be useful in guiding the partnership regarding future projections of climate change impacts on the attainment of the Bay TMDL and water quality standards.

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Improving soil health has gained traction within the farming community because of its importance to long-term crop production and watershed health. To date, management focuses on in-field crop management practices such as reducing tillage, following 4R nutrient stewardship guidelines, and maximizing vegetative cover throughout the year. Guidelines do not address agricultural water management, despite that soil moisture primarily drives underlying soil health processes. In January 2020, STAC partnered with the Foundation for Food and Agriculture Research, West Virginia University’s Institute of Water Security and Science, The Nature Conservancy, and the Transforming Drainage partnership and convened experts to explore the importance of agricultural water management to achieving soil and watershed restoration goals.

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