Triadelphia Reservoir is an 800-acre impoundment located in Howard and Montgomery Counties, Maryland. Created in 1943 by damming the Patuxent River, the reservoir has an average depth of about 50 feet and features approximately 15 miles of shoreline. Maintained by the Washington Suburban Sanitary Commission (WSSC) as a drinking water source, this scenic reservoir offers peaceful fishing opportunities away from the noise of gas-powered motors, as only non-motorized watercraft are permitted. The reservoir is open for recreational use from March 15 through November 30, conditions permitting.
Learn what type of fish are at Triadelphia Reservoir and what's needed to catch them.
Micropterus salmoides
Micropterus dolomieu
Oncorhynchus mykiss
Salmo trutta
Esox lucius
Sander vitreus
Pomoxis nigromaculatus
Lepomis macrochirus
Ictalurus punctatus
Cyprinus carpio
Semotilus corporalis
Lepomis cyanellus
Lepomis gibbosus
Lepomis auritus
Lepomis microlophus
Morone saxatilis
Pomoxis annularis
Morone americana
Catostomus commersonii
Ameiurus natalis
Perca flavescens
Learn how to get on Triadelphia Reservoir. Uncover great fishing access points, boat ramps, and all the facilities you need for an unforgettable day on the water. Some locations shown may border or include private property. Always check property boundaries and applicable regulations before visiting. onWater's Public & Private Land layer can help you plan your access with confidence.
See public and private land boundaries along the water, turn on private parcels with owner details to know where permission is required, and find land-trust parcels that offer permitted fishing access.
What you need to float or boat Triadelphia Reservoir, and when to apply.
Boater pass · All boaters · Required Mar 15 to Nov 30
Boaters ages 16 to 65 on the WSSC reservoirs need a daily or seasonal watershed use permit, and only oars, paddles, sails or electric motors are allowed.
Checked Nov 4, 2026 with Patuxent Reservoirs Watershed
When using any type of watercraft to access a body of water, it is important to follow all federal, state, and local rules and regulations. These rules and regulations include boat permitting and licensing, invasive species inspections and stamps, life jacket and PFD rules, motor size and horsepower restrictions, noise limitations, restrictions on personal watercraft, and many more. Visit the web link below for the most current rules and regulations for this body of water.
Individuals under the age of 16 are not required to obtain a license to sport fish/crab. They can, however, purchase a recreational crab license if they want to catch the bushel of crabs allowed with that license.
This river has a variety of species and regulations, including potential floating and/or watercraft restrictions. Because this river is specially managed for species, seasons, angling methods, and watercraft, it is strongly encouraged you check all federal, state, and local regulations before fishing. Visit any of the links below, inquire locally, or contact a local fly shop to learn current regulations and restrictions.
Current law in Maryland seems quite friendly to public access to floatable water, allowing access at all public bridges and road crossings of floatable water. Though historically the state has only recognized waters subject to the ebb and flow of tides as navigable, that definition appears to have broadened. A complete list of public waters and access points is available on the Maryland DNR website.
The onWater Fish app keeps this water's access points, species and conditions in your pocket, with the tools you use once you're there.
Download the map around Triadelphia Reservoir to use it offline when coverage drops.
Keep a private fishing journal for Triadelphia Reservoir to find where and when fish are biting for you.
Find drop offs, ledges, channels, points and shallow flats with Garmin depth charts in the app.
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See the best times to fish Triadelphia Reservoir and check the forecast before you go.
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