The Brookhurst out-flow is actually a part of the Santa Ana River Jetties. It is actually a combination of drainage from storm drains further inland and the tidal surge that flows into the HB marshes. The out-flow is protected by a couple of decent sized jetties that help to keep it from silting up to badly.
The combination of sand from the drainage and the disruption in the longshore bar current (which is responsible for the N-S sand movement along the coast) helps to build a part of one of the most consistent sand bars in North Orange County. The bar generally starts up around the Brookhurst jetties and then ends down past the Santa Ana River Jetties.
Overall this wave is pretty good most of the time and can be excellent on the right swell mix. The sandbar helps keep it breaking through all but the most extreme high tides. The wave is pretty steep and hollow and can get pretty closed out on bigger S and WNW swells. Again, like most of the HB spots, you want the magic swell combo mix of S and WNW energy and offshore winds.
This spot actually does pretty well on windswell too. The shallower sandbar helps the shorter-period swell set up further off the beach, and in a more energetic fashion that a deeper bar would.
One big drawback about Brookhurst is the water quality. The combination of pollutants from the storm drains and the junk that comes down the Santa Ana river keeps water-quality on the marginal side most of the year. If there is any sort of rainfall it knocks the water quality right into the hazardous range.
Best swell direction: SE-SW (160-210+) and W-NW (260-290)
Best Wind: N-NE-E, light-moderate Santa Ana winds are the best.
Sea Floor: Sand…really shallow sand, and few rocks near the jetties
Best Season: Summer, Fall, and Winter can all be equally great. Fall is the most consistent.
Crowds: Can be crowded when it works…naturally it gets smaller as the waves get bigger.