The Anacostia River Trail is part of the National Park System and only unassisted bicycles could be used in the park. This changed in August 2019 when regulations came into effect allowing e-bikes on designated paths in national parks.
Does that mean that e-biking is allowed on the Anacostia River Trail ?
E-biking is allowed on the Anacostia River Trail where other types of bicycles are allowed. But, be aware of the small print.

The Kenilworth Aquatic Gardens at the Anacostia River Trail are famous for the Victoria Water Lily.
E-biking on the Anacostia River Trail is allowed only if you pedal to propel your e-bike and if the e-bike meets the following requirements:
Below is text from the Superintendent's Compendium or Record of Determination, in case you want to read the text allowing e-bikes on the Anacostia River Trail.
Superintendent's Compendium or Record of Determination
2019
E-bikes are allowed where traditional bicycles are allowed. E-bikes are prohibited where traditional bicycles are prohibited.
Except where use of motor vehicles by the public is allowed, using the electric motor continuously to move an e-bike without pedaling is prohibited.
An e-bike is a two- or three-wheeled cycle with fully operable pedals and an electric motor of less than not more than 750 watts (1 h.p.) that provides propulsion assistance.
Amended per the October 2, 2020 and November 2, 2020 updates. It is to expected that the 2020 compendium will include amendments pertaining class 2 e-bikes, made on November 2, 2020.
Authorized in 1932, Anacostia Park, site of the 1932 “Bonus March,” is 1,200 acres stretching the length of the Anacostia River. The southern portion is a multi-use recreational park with shoreline and river access, ball fields, tennis courts, swimming pool, roller skating pavilion, riverwalk trail, and picnic areas.
The northern section contains Kenilworth Park and Aquatic Gardens which is the only NPS park dedicated to cultivating water-loving plants.
Transferred from Office of Public Buildings and Public Parks of the National Capital Aug. 10, 1933.
Acreage: 8,693.37 Federal: 8,462.47 Non-federal: 230.90.
source: np Index
Conclusion
Most e-bikes sold in the US have a motor of less than 750 watts, operate with functional pedals and have two wheels. Unless regulations change, e-biking on the federal section of the Anacostia River Trail is permissible if you meet the requirements as stated above.
The Anacostia River Trail System is a network of several trails of which the Anacostia River Trail is part. Several pilots are ongoing in Prince Georges County and Montgomery County that allow class 1 e-bikes on trails within the system in the counties.
Update: You are now allowed to e-bike on the Kenilworth Aquatic Gardens Access trail to Anacostia River Trail.
Note: If you buy an E-bike conversion set, ensure that the motor is not more than 750 watts to gain access to NPS trails when permitted by the superintendent of the park.
Interested in E-biking on the Anacostia River Trail?
Explore our growing collection of self-guided e-biking trail descriptions.

Gregory discovered e-biking after 20 years of overseas work as project manager for the World Bank and USAID. He writes about e-mobility and e-biking in the DMV area, and loves the outdoors (white water kayaking, hiking and biking). He lives with his wife, Janet and Queenie the cat, in Washington DC. He recently e-biked 4,685+ miles across America and raised $180,000 for a charity.
Favorite e-bike: Riese & Muller Super Charger Class 3 touring e-bike.
Dr. Gregory F. Maassen
FOUNDER E-BIKE LOVERS
As usual, please check the latest regulations before heading out as we do not provide legal advice on this website.
References
https://www.nps.gov/aboutus/upload/NPIndex2012-2016.pdf
https://www.nps.gov/nace/learn/management/lawsandpolicies.htm [Accessed 14 Dec. 2020].
Nps.gov. (2020). Electric Bicycles (e-bikes) in National Parks - Biking (U.S. National Park Service). [online] Available at: https://www.nps.gov/subjects/biking/e-bikes.htm [Accessed 14 Dec. 2020].
https://www.anacostiaws.org/images/Files/maps/2017_Update_ART_web.pdf