Column: To clean up Oahu’s coastal waters, focus on storm drains

Two months ago, it rained hard, real hard, and we were all aghast at the damage from flooding and the huge mess it made of our beaches, surf spots and reefs. Now it’s spring, and we’re all back to enjoying the beaches, and don’t want to think about storm drains.

But that’s a problem: Honolulu has a history of ignoring environmental issues — until the U.S. Environmental Protection Agency (EPA) reminds us, and those “reminders” come in the form of expensive consent decrees.

In 2005 an EPA consent decree required the state Department of Transportation to clean up its storm drains at a cost to taxpayers of $50 million. A consent decree in 2010 required the city to upgrade its sewage treatment system at a cost to taxpayers of $4.5 billion. About $1.5 billion is still outstanding to upgrade the Sand Island wastewater treatment plant (WWTP) from primary to secondary treatment. Two decades of monitoring the disposal site two miles offshore have demon- strated no adverse impacts. Independent engineers and environment- al professionals generally agree that this expensive upgrade is completely unnecessary — but it must be done because it’s in the consent decree.

What’s worse: city stormwater discharge, or sewage effluent? Every day, Honolulu’s four main WWTPs discharge about 105 million gallons of treated sewage into the offshore ocean, enough effluent to fill the Aloha Stadium up to just above the orange seats, every day. The solids in this water (about 11.5 tons) would be enough to fill a couple of dump trucks sitting on the 50-yard line. In a year, this would total 4,000 tons of solids.

Most of Hawaii’s 670 miles of storm drains were designed and constructed a half-century ago when the only engineering goal was to move stormwater as quickly as possible away from urban areas. Unfortunately, these drains are also efficient at moving pollutants downslope into our streams and coastal ecosystems. Studies have been conducted in several watershed storm- drain systems to quantify pollutant discharges on an annual basis.

Extrapolating from these studies to the whole stormwater system yields an annual load of 8,700 tons of sediment — more than double the load from the WWTPs.

More importantly, these pollutant loads are not pushed far offshore and dispersed deep into the ocean like the sewage outflow, but are delivered directly to our streams, beaches, surf spots, coral reefs and other nearshore ecosystems. Suspended solids are only the beginning; stormwater also carries bacteria, nutrients, road gravel, heavy metals from brake linings, urban pesticides, animal feces and other pollutants.

Under the EPA stormwater permit system, cities have been strongly encouraged (i.e., forced) to make pollution abatement improvements to their storm drain systems. Honolulu has avoided these requirements through costly legal negotiations. But realizing the eventual necessity for improvements, the city is trying to create a “stormwater utility.” The formation of a stormwater utility will increase the budget from its present approximate $40 million per year to about $140 million per year, by instituting a separate tax base and billing, similar to that of the Board of Water Supply.

Increasing funds to modernize the stormwater infrastructure will greatly benefit those of us who like to swim and surf in clean water. But, do we really need to create a separate tax base just for stormwater? Why not just convince the city to authorize sufficient funding to properly provide for these services? Alternatively, could we have the EPA reconsider the useless $500 million “improvements” to the Sand Island WWTP and use these funds to improve the storm drain system? Perhaps we should prioritize anticipated federal stimulus funds toward stormwater infrastructure. Any of these are better than following past practices and waiting for the EPA to lay another consent decree upon us.

Robert Bourke is an environmental scientist with 30 years’ experience managing teams on an array of coastal and aquatic projects in Hawaii and the Pacific islands.