Publications

Publications are listed by year

A water quality binning method to infer phytoplankton community structure and function

Authors: Claire Buchanan Published in February 2020

Aspects of phytoplankton community structure (e.g., taxonomic composition, biomass) and function (e.g., light adaptation, net oxygen production, exudation) can be inferred with a binning method that uses water transparency (Secchi depth), dissolved inorganic nitrogen, and ortho-phosphate to classify phytoplankton habitat conditions in the surface mixed layer. The method creates six habitat categories, forming a disturbance scale from turbid, nutrient-enriched waters (“degraded”) to clear waters with bloom-limiting nutrient concentrations (“reference”). Across this disturbance scale, estuarine phytoplankton exhibit strong differences in chlorophyll a, count-based biomass, trophic mode, average cell size, photopigment cell content, taxonomic dominance, and the frequency of algal blooms. Differences in ambient dissolved oxygen and dissolved organic carbon are also observed. Two alternate states are apparent, separated primarily by water transparency, or clarity.Water transparency determines cellular light-adaptation and the potential for photosynthesis and growth; nutrient concentrations determine how much of that potential can be realized if and when light becomes available. In Chesapeake Bay, Secchi depth thresholds separating the two states are 0.7–0.9 m in shallow, well-mixed, low salinity waters and 1.2–2.1 m in deeper, stratified, higher salinity waters. The water quality binning method offers a conceptual framework that can be used to infer the overall state of a phytoplankton population more accurately than chlorophyll a alone.

The article was published in Estuaries and Coasts (2020). DOI link: https://doi.org/10.1007/s12237-020-00714-3. Please contact us for a full copy of the report.

 

Assessing the effectiveness of riparian buffers for reducing organic nitrogen loads in the Coastal Plain of the Chesapeake Bay watershed using a watershed model

Authors: Sangchul Lee, Gregory W. McCarty, Glenn E. Moglen, Xia Li, Carlington W. Wallace Published in June 2020

Riparian buffers are an important conservation practice to mitigate water quality degradation in the Coastal Plain of the Chesapeake Bay watershed (CBW). Although forested and grassed riparian buffers have been implemented in this region through government programs, the impacts of riparian buffers on water quality have been rarely examined. The objective of this study was to assess the long-term effects of riparian buffers to improve water quality in the Coastal Plain of the CBW. A watershed model, Soil and Water Assessment Tool (SWAT), was employed for this study. Considering impacts of model uncertainty (i.e., equifinality) on the effectiveness of riparian buffers, we adopted all parameter sets that produced acceptable simulation results. Multiple riparian buffer implementation scenarios were developed to generate the baseline condition on total organic nitrogen (TON) loads without riparian buffers and examine variation of TON loads with areal coverage of riparian buffers. Through the calibration processes, a total of 235 acceptable parameter sets were identified and used to simulate TON loads. The simulation results indicated that riparian buffers significantly reduce TON loads. Without riparian buffers, annual TON loads from the 220 km2 study watershed were 18 to 34 metric tons, but declined to 8 to 21 metric tons with riparian buffers. The effectiveness of riparian buffers on reducing annual TON loads increased from 17% to 45% with an increase in the extent of riparian buffer implementation. The effectiveness of riparian buffers tended to be higher during early spring than other seasons as high soil water conditions promote occurrence of surface water flow and thus TON loads. Riparian buffers were more efficient on croplands than other land use types due to high soil nutrient levels caused by fertilizer applications. The effectiveness of riparian buffers differed considerably by parameter set. Thus, efforts to consider model uncertainty are important to provide better insight into the impacts of conservation practices. This study supports ongoing riparian buffer programs for the Mid-Atlantic Coastal Plain by demonstrating the effectiveness of riparian buffers and informing implementation guidelines.

Published in the Journal of Hydrology, Volume 585, June 2020: https://doi.org/10.1016/j.jhydrol.2020.124779

Integrating Sustainable Water Resource Management and Land Use Decision-Making

Authors: Heidi L. N. Moltz, Carlington W. Wallace, Erfaneh Sharifi, and Karin Bencala Published in August 2020

Human uses of land and water are directly linked and must, therefore, be managed with each other in mind. This paper puts forward an approach for integrating sustainable water resource management into local land use decision-making in the Potomac basin. The approach includes developing a clear understanding of the current regulatory, programmatic, and financial approaches to land use management; identifying opportunities from innovation; and developing a flexible, stakeholder-based framework for moving forward. Four opportunities for innovation were identified in the Potomac basin utilizing this approach, including enhancing coordination and access to information, promoting incentives to achieve desired outcomes, encouraging and promoting innovation, and integrating programs to achieve multiple objectives. The successful integration of land and water decision-making requires a sustained, long-term commitment to improvement rather than a one-time fix mentality. Initial steps for implementation include identifying and engaging diverse partners, as well as establishing channels for information dissemination. The lessons learned from this work may prove valuable to decision-makers in other regions to holistically manage diverse land and water resources.

The article was published in Water 2020, 12(8), 2282; https://doi.org/10.3390/w12082282.

Planning Assistance to States: Jennings Randolph Lake Scoping Study Phase II Report

Authors: Laura Felter, Julia Fritz, Cherie Schultz, Claire Buchanan, and Gordon Michael Selckmann Published in April 2020

The watershed of the North Branch Potomac River experienced severe environmental degradation and flooding in the 20th century. A dam across the river mainstem was completed in 1982, creating Jennings Randolph Lake. The lake and dam are operated by the U. S. Army Corps of Engineers for four authorized purposes: control floods, dilute downstream pollution, supply drinking to Washington DC during droughts, and provide recreation. Water quality in the North Branch watershed has improved considerably since the dam was built due to many factors, including regulatory enforcement, mine runoff mitigation, wastewater treatment, infrastructure improvements, forest regrowth and the abatement of acid rain (see ICPRB report 19-4). This pilot study was done to determine if an update of the 1997 Reservoir Regulation manual is appropriate at this time. The report reviews and evaluates each of the authorized purposes in terms of their original management goals and objectives, current relevance, and future application.

A copy of the report is available here.

Pilot Analysis of Maryland Phase I MS4 Permit Water Quality Data

Authors: Rikke Jepsen and Deb Caraco | Pub: # ICP 20-2 | Published in May 2020

The Interstate Commission on the Potomac River Basin (ICPRB) and the Center for Watershed Protection (CWP) conducted a pilot study of water quality data collected at Moores Run in Baltimore City, Airpark Business Center in Carroll County, and Urbana in Frederick County to characterize stormwater discharges and evaluate watershed restoration activities. The overarching objectives were to determine if there are trends in water quality over time and, if any trends are found, attempt to relate them to watershed restoration efforts or the implementation of Best Management Practices (BMPs). Another goal of the pilot study was to provide recommendations for future analysis of MS4 monitoring data and improving the monitoring requirements in Maryland’s Phase I MS4 permits.

Tables and figures are available here.

2020 Washington Metropolitan Area Water Supply Reliability Study: Demand and Resource Availability Forecast for the Year 2050

Authors: Prepared by S.N. Ahmed, H.L.N. Moltz, C.L. Schultz, and A. Seck | Pub: # 20-3 | Published in September 2020

Every five years since 1990, ICPRB’s Section for Cooperative Water Supply Operations on the Potomac (CO-OP) has conducted a water demand and resource availability forecast for the Washington, D.C., metropolitan area. These studies assess whether or not the current water supply system will be able to meet the needs of the region 20 or more years in the future.

Learn more about these reports on the CO-OP Long-Term Planning page.

Contact us for more information