If for you bicycling the nearly 10-mile long bike path along the south shore of Lake Pontchartrain in Jefferson Parish is an infrequent pleasure you may not be aware of a slick spot at the Causeway underpass that has suddenly developed. A small leak in the levee (city side) is keeping a short patch of the levee service road/bike path constantly wet near the bottom of the levee at a sharp turn there.
Not only would a wet spot in a turn at the bottom of a steep, short decline be a problem all by itself, this being summer in south Louisiana, a thin carpet of slippery, hard to see algae is growing in the damp patch. Riders barreling down the levee trying to squeeze every mile an hour they can with the rare opportunity of riding downhill, have hit that slick patch at 20-25 mph or better and gone down. One rider I spoke to said this is not speculation: she saw it happen once.
Where the bike path turns away from the lake and crosses the levee to go under the Causeway is dangerous when dry. At the bottom of the steep incline are sharp turns. Gravel collects in those turns and riders risk a spill when trying to make the turn at speed. An unexpected patch of slippery algae on the road/path adds considerably to the risk.
Most of where we ride in New Orleans is flat as a pancake. It is hard to pass up a chance to tempt fate by risking a few speedy seconds zooming downhill to have a rare "here, hold my beer while I do this," experience.