Bay Crossings Article

Boaters Can Help Keep Sewage out of the Bay

Deb Self, Executive Director
From the May 2011 edition of Bay Crossings

First, a sewage spill update: since I wrote last month about our annual Bay Area winter sewage spills, the number of gallons of sewage spilled has doubled! After a very rainy March, we can now say that nearly a quarter billion gallons of raw or undertreated sewage have entered San Francisco Bay and its tributaries this winter.

With 40 treatment plants and 17,000 miles of publicly-owned sewer pipe in the Bay Area, we have a lot of sewage collection pipes, and most are in very poor condition. But, as I have reported here recently, San Francisco Baykeeper is making some headway, as exhibited by a new round of sewage spill reports from cities under consent decrees with Baykeeper. On the Peninsula, where we began targeting troubled collection systems in 2006, cities have begun upgrading their infrastructure and have reduced their number of sewage spills by 60 percent in just the last two years. Now that we have settlements with 10 new cities this year, most of the worst-performing systems in the region are under consent decrees with Baykeeper and are finally making long-overdue repairs.

While the municipal sewage problem is certainly one of the Bay’s biggest challenges, there’s another less heralded sewage problem: marinas. Many boaters think their contributions are too small to make a difference, but consider that there are about 100,000 recreational boats on the Bay and that between 10 and 20 percent are used as a primary residence. Further, the impact of boat sewage is localized in the shallow waters of coves and in marinas that receive little tidal flushing, where the water can become quite degraded.

I also want to correct the common misconception that salt water somehow sanitizes raw sewage. To the contrary, sewage pollution carries disease-causing pathogens, infectious bacteria and viruses into the estuary’s water, causing exposed swimmers to suffer from sore throats, sinus infections, diarrhea and skin infections. Marine mammals, birds and other creatures in our Bay can also suffer health effects. Additionally, sewage pollution contributes to algal blooms and reduces the amount of oxygen available in the water for fish and aquatic plants.

Most boaters know that it is against federal law to have an installed toilet on a boat unless it has a Coast Guard-certified and operable Marine Sanitation Device (MSD). The most common type of MSD is a holding tank that contains the sewage until it can be pumped out and routed to a municipal sewage treatment plant. Holding tanks are required by most marinas for people who live onboard their boats, and the Coast Guard requires that any Y valve that would allow bypass of the holding tank be closed and locked. However, there appears to be little enforcement of this requirement, and it seems that rather than use pump-outs, some boaters either bypass their holding tanks or empty the tanks directly into the Bay.

The other two types of MSDs are “flow-through” treatment systems that use an electrical current to reduce the bacterial count and macerate the waste to remove floating solids. Unfortunately, even if the unit is functioning properly, the discharged foamy film still degrades water quality—and creates an unpleasant environment in the marina. Additionally, the electrodes in the unit often become corroded and require replacement, an expensive fix many owners don’t pursue. Some units also require potentially toxic chemicals and biological agents that can contribute to water pollution.

While Type I and II MSDs have their problems if not maintained, the bigger problem may be with direct (and illegal) discharge of untreated sewage. A recent review of boating message boards revealed one boater’s philosophy: “Bucket and chuck it . . . Just wait until night.” I expect most Bay Area boaters have a different environmental ethos and a love for the Bay, but all local boaters have to take responsibility for the collective impact that illicit sewage dumping can have on their marinas and the Bay.

Baykeeper encourages all boaters with marine toilets to use pump-outs. If a pump-out station at the local marina is broken, report it. Either use a stationary pump-out system regularly or contract with a mobile pump-out service such as BayGreen. Baykeeper also encourages Bay Area marinas to conduct regular inspections of MSDs and keep logs of pump-outs. A little oversight could make a big difference in our Bay’s health.