Wheeler North Reef

Wheeler North Reef is a field of quarried boulder spread across the sand shelf half a mile off San Clemente, in 38 to 50 feet of water depending on position and tide. The reef runs about 2.5 miles along the coast, from San Mateo Point at the San Diego County line north to just above San Clemente Pier, and it is the largest artificial reef ever built in the United States. It carries the name of Wheeler J. North, a marine biologist who spent his career studying California kelp forests.

The reef exists because of a nuclear plant. A 1989 Marine Review Committee report found that cloudy water discharged by the San Onofre Nuclear Generating Station's cooling system drifted south along the coast, cut the sunlight reaching the seafloor, and damaged roughly 180 acres of the San Onofre kelp bed. The California Coastal Commission required Southern California Edison to replace what was lost. Construction came in 3 stages. An experimental reef of 22 acres went down in 1999 as 56 separate modules built at different rock densities, to find out which density grew kelp best. Phase 2 followed in 2008 and added 152 acres across 17 polygons, bringing the main reef to about 174 acres. A third phase finished in July 2020, placing 150,975 tons of rock over 198 acres of low-relief bottom north and inshore of the first two.

The rock itself sits low. Pieces run 1 to 3 feet across in a single layer that rises no more than about 1.5 feet off the sand, and that was deliberate. Kelp along this stretch of coast holds on best over low natural outcroppings, so the design copied them instead of building height. Giant kelp anchors on the rock and grows to the surface from about 40 feet, which makes the reef a kelp forest biome. The bare boulder under the canopy, and the polygons where kelp has not taken hold, are a rocky reef biome. More than 200 species of algae, fish, and invertebrates have been recorded here, giant sea bass among them.

Scuba and freediving from a boat are the way people work the reef, and hook-and-line fishing over it is common. Visibility runs 10 to 25 feet, with summer and fall the better seasons, though red tides thin the water some summers. Dana Point Harbor is the nearest launch at about 7 miles north, and Oceanside Harbor sits about 18 miles south. Half a mile is within kayak range in calm weather, but San Clemente has no boat ramp and the pier has no launch facilities.

No marine protected area covers the reef or the coast around it, and the nearest one is Dana Point State Marine Conservation Area, whose southern boundary falls several miles up the coast. Fishing and spearfishing are legal at Wheeler North Reef under standard California regulations, with no rule specific to artificial reefs in play.