Avalon attributes part of its poor water rating to recreational boats that enter Avalon Harbor, discharging many of their waste tanks into the harbor. If this type of discharge is seen, the boat is immediately removed from Avalon Harbor and prohibited from re-entering for one year. The boat owner is also fined by the City for the illegal discharge. The City has a "no tolerance" rule for this type of behavior.

Most polluted beaches

Here's a list ranking of the most polluted beaches in California, as compiled by the environmental group Heal the Bay.

1. Avalon Harbor Beach on Catalina Island (Los Angeles County)

2. Cabrillo Beach harborside (Los Angeles County)

3. Pismo Beach Pier (San Luis Obispo County)

4. Colorado Lagoon (Los Angeles County)

5. Santa Monica Municipal Pier (Los Angeles County)

6. City of Long Beach at Los Angeles River outlet (Los Angeles County)

7. Poche Beach (Orange County)

8. Surfrider Beach at Malibu Creek (Los Angeles County)

9. Campbell Cove State Park Beach (Sonoma County)

10. Doheny Beach at San Juan Creek (Orange County)

The question is largely unanswered as to the actual cause of this pollution.

The City of Avalon has taken several steps to correct this problem including:

The Dye Tablet Program for all recreational boat flushing systems wherein a bright dye is immediately seen surrounding a boat if it discharges into the harbor.  he City has implemented a cleanout of all diverters twice a week (Mondays and Thursdays) to ensure the effectiveness of these devices. This basically means that no runoff from the street and storm drain system enters the Bay during the summer months.

Low Flow Diverters for storm drains: Storm drains carry all water and pollutants that are on our streets and flow directly to the Bay untreated. Runoff from storm drains, also widely known as “urban runoff” is the number one source of pollution into Southern California ocean waters.

Bird Exclusion Wires to keep microbes from polluting the bay placed where birds normally perch.

Scources amd Mitigation Study to further determine cause including plumbing under the wharf, and sewer systems.