Publication date: July 6th, 2020 in Report
Understanding Chesapeake Bay Modeling Tools
The Chesapeake Bay Program uses state-of-the art science and monitoring data to replicate conditions of the Chesapeake Bay watershed. This information is then used by decision-makers at the federal, state and local levels to determine how best to restore and protect local waterways, and ultimately, the Chesapeake Bay. By combining advanced modeling tools and real-world monitoring data, we gain a comprehensive view of the Chesapeake ecosystem—from the depths of the Bay to the upper reaches of the watershed.Download
Publication date: May 13th, 2020 in Report
Cropland Irrigation BMP Expert Panel Report
This Expert Panel was charged to determine the water quality benefit associated with the practice of irrigation on cropland, a practice of specific importance on the Delmarva Peninsula region of the Chesapeake Bay watershed (CBW). This region is characterized by unpredictable rainfall patterns and wide-spread course-textured sandy soils with low water retention capacity. The primary intention of cropland irrigation is to increase crop yield and consistency. The literature review process revealed limited research directly addressing the impacts of irrigation systems on respective local or regional water quality, in contrast to other partnership-approved Best Management Practices (BMPs), such as cover crops and conservation tillage. The fates of field-applied nitrogen (N) and phosphorus (P), or sediment loss due to erosion are of specific concern in regard to water quality. Taking into account the agricultural practices relevant to the CBW, the Panel narrowed its focus to center-pivot, lateral move and traveling gun irrigation systems on corn (grain or silage). The panel was also limited to addressing N leaching, as there is not sufficient data available addressing P and sediment related to cropland irrigation at this time.
The Chesapeake Bay Program’s (CBP) Agriculture Workgroup (AgWG) asked the panel to consider several aspects of cropland irrigation when reviewing the research findings. Primary among them was to refine the current CBP interim BMP definition and N efficiency value for cropland irrigation, accounting for possible deviations in efficiency values based on weather variability across growing seasons. The panel determined that it cannot refine the estimated interim N efficiency value at this time. The research currently available does not sufficiently substantiate a water quality benefit associated with cropland irrigation. The panel was also asked to consider creating separate efficiency values based on decreased variation in yields with irrigation, water management of irrigated systems, and fertigation. The panel determined that these factors are not mutually exclusive. All are interrelated in influencing potential loss of N from irrigated fields. For this reason, they are not considered as separate systems in this report.
The panel elected the Delmarva Peninsula portion of the watershed as the focus of this report due to the prevalence of cropland irrigation in that region. However, much of the literature related to irrigation comes from the mid-west United States, where irrigation of cropland has been ubiquitous across the agricultural landscape for some time, due to climate conditions that leave crops regularly subject to moisture stress. Additionally, most of the research is focused on comparing various irrigation systems to each other, with the goal of defining the system that provides the greatest yields, water use efficiency (WUE), nitrogen use efficiency (NUE), and/or economic benefits. Few studies consider the impacts, either beneficial or deleterious, of irrigated cropland on surrounding water quality. Among the limited publications addressing nutrient transport beyond the root zone, some found greater loss of N from irrigated conditions in comparison to dryland conditions, indicating a potential detriment to local water quality. Within the CBW where irrigation is a growing practice, the baseline condition remains dryland agriculture. While many studies compared center-pivot irrigation to other systems (e.g., furrow, drip), there was seldom a control dryland condition.
The Expert Panel agreed that there is not sufficient science-based research available to indicate a reduction in N losses due to irrigation of corn, therefore an N efficiency value cannot be established at this time. This does not preclude the possibility of revisiting cropland irrigation as a BMP for a future expert panel, should a more robust catalogue of scientific research literature addressing cropland irrigation management and its water quality impacts emerge. In that vein, the panel strongly endorses further research on the impacts of cropland irrigation on nutrient and sediment loss and encourages the reader to review the Ancillary benefits and unintended consequences (p.38) and Future research and management needs (p.40) sections of this report.Download
Publication date: March 25th, 2020 in Report
Bay Barometer: Health and Restoration in the Chesapeake Bay Watershed (2018-2019)
The data in Bay Barometer reflect the Chesapeake Bay’s health over the course of many years and, in some cases, decades. The publication offers a snapshot of the best available information from 2018 and 2019 on ecological health and our efforts to protect and restore the nation’s largest estuary, as well as our progress toward achieving the goals and outcomes of the Chesapeake Bay Watershed Agreement.Download
Publication date: March 18th, 2020 in Report
Wetland Rehabilitation, Enhancement and Creation BMP expert panel report
The Wetland Workgroup approved the formation of this expert panel to evaluate the effectiveness of nontidal wetland best management practices (BMPs) to reduce loads of nitrogen, phosphorus and sediment to the Chesapeake Bay. This panel was formed to expand on the CBP-approved report by a previous Wetland Expert Panel that clarified the wetland restoration BMP and established two nontidal wetland land uses in the Phase 6 Chesapeake Bay Watershed Model (WEP, 2016).Download
The current panel first convened in November 2017 and deliberated its approach and recommendations over the subsequent months. This report describes the panel’s recommendations for review, feedback and approval under the Chesapeake Bay Program’s Protocol for the Development, Review, and Approval of Loading and Effectiveness Estimates for Nutrient and Sediment Controls in the Chesapeake Bay Watershed Model, or “BMP Review Protocol.”
The expert panel worked diligently to articulate BMP efficiencies for wetland creation, rehabilitation and enhancement with respect to the available literature and the CBP-approved wetland restoration BMP. As with wetland restoration, the recommended wetland creation BMP is simulated as a land use change that also reduces upland loads using the above efficiency value. The recommended wetland rehabilitation BMP is not a land use change, but the efficiency is applied to upland land uses. Further details for how the BMPs will be reported for progress runs and simulated in the Watershed Model are provided in Appendix B. As explained in section 5, the panel recommends that wetland enhancement should not be a BMP for purposes of achieving nutrient and sediment reduction targets under the TMDL, as simulated in the Watershed Model.
Publication date: April 2nd, 2019 in Agreement
Bay Barometer: Health and Restoration in the Chesapeake Bay Watershed (2017-2018)
The data in Bay Barometer reflect the Chesapeake Bay’s health over the course of many years and, in some cases, decades. The publication offers a snapshot of the best available information from 2017 and 2018 on ecological health and our efforts to protect and restore the nation’s largest estuary, as well as our progress toward achieving the goals and outcomes of the Chesapeake Bay Watershed Agreement.Download
Publication date: June 27th, 2018 in Report
CBSAC 2018 Blue Crab Advisory Report
Annual report published by the Chesapeake Bay Stock Assessment Committee on the status of the blue crab population in the Chesapeake Bay and management advice for Bay jurisdictions.Download
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