Lac du Der is the biggest artificial lake in France — four thousand eight hundred hectares of managed Champagne floodplain, built in 1974 to stop the Marne from periodically drowning Paris. The ecology it has developed in the half-century since is startlingly productive: vast shoals of roach and bream, which in turn feed pike that grow to sizes people in the Paris basin used to think belonged only in the Baltic. The fly fishery for pike here is now well established — there are guides, specialist tackle shops, and an entire seasonal calendar organised around the April opening. The lake is drawn down through winter for flood control and refills in spring, which creates rich feeding on the flooded margins exactly when the pike are most aggressive. Bring big flies, a fast-sinking line for the deep drop-offs, and a floater for the margin work. Water is coloured; pike are plentiful; do not expect trout.
- Reservoir
- Clay