Assessing the Effectiveness of the Anacostia River Tunnel in Reduction of Eutrophication

Principal Investigator:

Caroline Solomon

Start/End Year:

2018 - 2020


Gallaudet University

Co-Principal Investigator:

Patricia Glibert, Horn Point Laboratory, University of Maryland Center for Environmental Science

Strategic focus area:

Healthy coastal ecosystems


The Anacostia River is among the most polluted tributaries in Chesapeake Bay. With substantial algal blooms and bacterial contamination, it has placed those who recreate on the water at considerable health risk. The first phase of a recently completed, multi-billion dollar infrastructure project, the Anacostia River Tunnel, which will retain and divert sewage and storm water effluent is due to be operational by March 2018. The tunnel project is award-winning from the perspective of the engineering community, but the environmental outcome is yet to be determined. While it may be years before the full infrastructure project is complete or full ecosystem recovery is seen, changes in phytoplankton and bacteria should be clearly evident in these first two years of project implementation. Accordingly, this Sea Grant project will address the hypothesis that the diversion of water and its associated nutrients will lead to an improvement in water quality, a shift in the community composition of phytoplankton species, and a reduction in sewage-associated bacteria. 

The specific objectives of this project are:

  1. To characterize the nutrients, phytoplankton and microbial diversity of the Anacostia River during the summer months, including after storm events;
  2. To conduct mesocosm manipulation experiments during the summer months to assess phylogenetic and functional responses to altered N and P and N forms;
  3. To initiate a citizen's monitoring program for bacteria in conjunction with the Anacostia Riverkeeper to convey whether it is safe to swim;
  4. To synthesize data across multiple years of study to advance our understanding of phylogenetic, functional and genetic diversity of algal communities as a function of altered nutrient loads, proportions and forms, and in response to change in these loads with the Anacostia Tunnel improvement project;
  5. To share data and findings with local management groups that serve the Anacostia River region, and communicate findings to the public through social media, public events and other forums.

Building on a considerable body of work on baseline conditions over the past few years, this project will bring new seasonal water column measurements, enclosure enrichment studies, and molecular approaches to determine if, indeed, a success story can be written. The PIs, together with their students, will use established relationships with the Anacostia Riverkeeper and the Anacostia Waterfront Trust to communicate with community groups via meetings, social media and the local press and implement a citizen science program to allow for rapid response regarding water safety


Assessing the Anacostia River Tunnel's Impact and Enlisting Citizen Science

Summary: Maryland Sea Grant-supported researchers studied changes in the Anacostia River's phytoplankton and bacteria to assess the effectiveness of a new wastewater remediation system, while also mobilizing and training citizen scientists to monitor their river and garnering interest from District of Columbia decision-makers.

Relevance: The Anacostia River, which flows through the nation's capital, is one of the Chesapeake Bay's most polluted tributaries. It has long been unhealthy for humans and aquatic organisms. Millions of gallons of urban sewage and stormwater runoff routinely flow into the river. Designed to reduce the combined sewer outflow by up to 80 percent, the 2.3-mile-long Anacostia River Tunnel began operating in March 2018. Studying changes in phytoplankton, bacteria, and the river's microbial community will help assess the tunnel's effectiveness in reducing algal blooms and bacterial contamination. Additionally, engaging citizen scientists to help continuously monitor the river will be critical to its ongoing restoration.

Response: Through a Sea Grant-supported project, two researchers, a Sea Grant fellow, and several undergraduate students from Gallaudet University synthesized four years of data on nutrients and phytoplankton collected biweekly and monthly before the tunnel's construction. They also conducted sampling after the tunnel began operating in spring 2018. Unrelenting rains made 2018 the wettest fall on record in Washington, D.C., leading to higher-than-normal stormwater runoff and nutrient loading from land and complicating efforts to accurately assess the tunnel's effectiveness. In 2019, 15 sampling trips were conducted, and two experiments were led by the MDSG fellow. The experiments manipulated water with various nutrient additions to understand which phytoplankton communities would develop under different nutrient regimes, helping to improve interpretation of the field data. 

Results: Working with the Anacostia Riverkeeper, the Sea Grant-supported project helped train 121 volunteers to sample for E. coli bacteria at multiple locations. Data from this new citizen-science effort is used weekly to update the SwimGuide, through which residents can evaluate the river's safety for swimming and other activities. At the 2019 Anacostia River Festival, more than 7,000 attendees interacted with the Sea Grant fellow and undergraduate students who presented a popular working model of a wastewater treatment plan to illustrate the tunnel's purpose. The researchers also shared the synthesis of the pre-tunnel monitoring data with the District of Columbia Department of Energy & Environment, which prompted it to encourage Gallaudet-a university for the education of the deaf and hard of hearing-to seek additional collaborative research opportunities and engagement with District officials.

Related Publications:

Gleich, SJ; Plough, LV; Glibert, PM. 2020. Photosynthetic efficiency and nutrient physiology of the diatom Thalassiosira pseudonana at three growth temperatures Marine Biology167(9) . doi:10.1007/s00227-020-03741-7. UM-SG-RS-2020-09.

Solomon, CM. 2019. Urea uptake and urease activity in the Chesapeake Bay Journal of Marine Research77:139 -168. doi:10.1357/002224019828474340. UM-SG-RS-2019-20.

Solomon, CM; Jackson, M; Glibert, PM. 2019. Chesapeake Bay's "forgotten" Anacostia River: eutrophication and nutrient reduction measures ENVIRONMENTAL MONITORING AND ASSESSMENT191(5) . doi:10.1007/s10661-019-7437-9. UM-SG-RS-2019-01.

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