Considerations for Monitoring Microplastics in the Non-Tidal Potomac River Archives

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Considerations for Monitoring Microplastics in the Non-Tidal Potomac River

The Interstate Commission on the Potomac River Basin’s 2022 Clean Water Act Section 106 Potomac Basin Water Quality Improvement grant included an activity to “assist water suppliers in VA, MD, and DC in developing microplastic sampling and analysis methodologies and conduct field sample collection.” This white paper, which explores the feasibility of a microplastic monitoring program in the nontidal Potomac basin, represents the output for this activity. Section 2 describes considerations for collecting and processing samples for microplastics analysis. Section 3 provides a brief explanation of analytical methods and quality control recommendations for the detection, quantification, and identification of microplastics.

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Improving probabilistic monthly water quantity and quality predictions using a simplified residual-based modeling approach

Uncertainty quantification between simulated and observed water quality simulations needs to be improved. This study generated and evaluated probabilistic hydrologic and water quality predictions in 18 locations across the U.S. using residual-based modeling. A Box-Cox transformation scheme group provided the best predictive uncertainties for all case studies. The tradeoffs in the performance metrics for a single variable predictive uncertainty in a single study watershed were more obvious than those for all hydrologic or water quality cases. Compared to a single realization of simulations, the ensemble average of hydrologic and water quality simulations better represented the predictive uncertainty, especially for large watersheds. This study recommends various opportunities via residual error scheme selection, data monitoring improvement, and hydrologic model enhancement to robust hydrologic and water quality predictive uncertainties. The results could improve the quantification of the predictive uncertainty of hydrologic and water quality simulations and guide probabilistic prediction enhancement.

More information about the paper is available on ScienceDirect.com.

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Potomac Basin Reported Water Use

In accordance with one of the technical recommendations of the Potomac Basin Comprehensive Water Resources Plan’s water use and supplies challenge area, this pamphlet has been produced to document and share high-level results. This pamphlet provides a “report on basin-wise water uses,” and ultimately acts as a first step toward estimating, “projected demands and consumptive demands.”

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Potomac Environmental Flows Workshop 2022

In 2021, Commissioners of the Interstate Commission on the Potomac River Basin (ICPRB) passed a Resolution on Enhancing Water Supply Resilience for the Washington Metropolitan Area. This resolution is the first step in updating the two foundational agreements of the Washington metropolitan area cooperative water supply system: the Low Flow Allocation Agreement (LFAA) of 1978 and the Water Supply Coordination Agreement (WSCA) of 1982. To facilitate such an update the resolution called for the following action items:

  • Develop a Task Force on the WSCA to reinitiate dialogue on revisions that would accurately reflect changing conditions. This includes the need for strengthening water security against spills, cybersecurity attack, and water scarcity and the ability to include additional suppliers;
  • Convene a Work Group to discuss the ten sets of options identified in the 2018 review of the LFAA; and
  • Convene scientific workshops on state-of-the-art approaches to environmental flows for large river systems.

To address the third action item, a virtual workshop was held over one-and-a-half days in May 2022, with the explicit purpose of answering the following questions with respect to the Potomac River, which supplies most of the Washington, D. C., metropolitan area drinking water:

  • Are there other approaches now for determining environmental flows in large, relatively unregulated rivers like the Potomac?
  • If there are, what data, analysis tools, and assessments are needed to make a scientifically defensible change?

The information presented and discussed during the workshop provides input to the LFAA workgroup in the event the group recommends revisiting the current environmental flow-by target used during low flow periods. The question of whether or not to study the flow-by was informally discussed during the workshop but the intent of the workshop was to gather the relevant information, not recommend a course of action.

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An Inventory of Potomac Basin Entities with a Role in Sustainable Water Resources Management

This pamphlet is used in concert with a spreadsheet inventory to identify entities in the Potomac basin that either directly or indirectly affect the realization of the Potomac Basin Comprehensive Water Resource Plan’s vision for the basin. It also summarizes the roles, responsibilities, and areas of authority of those entities to inform and integrate future comprehensive planning and implementation activities.

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2020 Washington Metropolitan Area Drought Exercise

This report describes activities conducted during the 2020 drought exercise. The exercise was virtual, and took place on Monday, Tuesday, and Wednesday, November 16-18, from 7:30 AM to 4:00 PM.
Communications during the exercise were via telephone, email, and Microsoft Teams Meeting, and all
operations were “simulated.” Twice daily email reports were sent out to stakeholders reporting on current flow and demand conditions and on simulated operations. The exercise included two special events:

  • An actual test release from Little Seneca Reservoir, which was conducted over an approximately
    12-hour period, beginning at 10:00 AM on Tuesday, November 17.
  • A webinar by Hazen & Sawyer on the use of the Potomac OASIS model to provide probabilistic
    information on future streamflows and reservoir storage levels. A PDF of the webinar on forecast informed reservoir operations is available.

Learn more about previous drought exercises and the ICPRB’s Section for Cooperative Water Supply Operations on the Potomac on the Drought Monitoring and Operations page.

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

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.

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Integrating Sustainable Water Resource Management and Land Use Decision-Making

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 202012(8), 2282; https://doi.org/10.3390/w12082282.

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

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.