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: 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
Publication date: January 11th, 2018 in Report
Holistically Analyzing the Benefits of Green Infrastructure
Changes in the regulatory landscape, coupled with budget-constrained environments, are driving local governments to search for new or evolving strategies and investments that deliver more value than conventional stormwater management practices.
In light of this challenge, green infrastructure (GI) is getting more attention as a stormwater management strategy. GI is described as a more holistic and multifunctional approach to stormwater management that can deliver benefits across the triple bottom line, mitigate water quality impacts, improve quality of life and enhance climate resiliency (US EPA, 2015).
The list of direct and indirect benefits arising from GI is fairly consistent across sources, but the scale and value of these benefits are not. Careful examination of peer-reviewed published literature, combined with existing guidance documents and studies, provide options for quantifying and monetizing the wide array of GI benefits. The various sources are diverse. They employ different valuation and assessment methodologies. Existing resources do not provide a unifying framework or standardization. Consequently, the methods require multi-disciplinary technical knowledge (engineering, economic and bio-physical) that stormwater managers do not generally have.
This document is intended for smaller local governments with stormwater programs that are responsible for regulatory compliance with municipal separate storm sewer system (MS4) obligations (e.g., Phase 2 communities). It outlines an approach to holistically evaluate the benefits of implementing green infrastructure. The guidance places emphasis on first understanding the goal and scope for assessing benefits. It uses the goal and scope to step the user through: (1) differentiating between direct benefits and co-benefits of GI, and (2) understanding when and how these benefits need to be characterized, quantified or monetized. This document is not intended to be a “how to” measure benefits for conducting benefit-cost analysis, but rather anapproach to tailor benefits and co-benefits identification and description to inform decision making and stakeholder engagement.
The report is organized into three sections with attachments.
- The first section introduces the concept of green infrastructure and describes some of the most common GI practices.
- The second section discusses the range of benefits and co-benefits often attributed to GI.
- The third section outlines an approach to assessing the benefits.
- Finally, the attachments provide case studies that illustrate how this guidance can be used.
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