Highway or road tunnel Road block, berm, or barrier* Gate on road* Highway or road with median strip Trailhead* T H RIVERS, LAKES, AND CANALS – continued Submerged marsh or swampIntermittent lake/pond Perennial lake/pond Dry lake/pond Wide wash Narrow wash Canal, fl ume, or aqueduct with lock Elevated aqueduct, fl ume, or conduit Aqueduct