San Diego has long been fighting a losing battle against poop.

Several decades ago, there was so much sewage in Mission Bay, it was driving away beach tourists. Decades before that, there was so much poo in San Diego Bay, it was corroding the hulls of Navy ships.

Sewage spills in San Diego are way down from 20 years ago, but they’re not gone.

Earlier this year, for instance, a county sewer pipe in East County broke, sending 900,000 gallons of human waste into Los Coches Creek. In late August, the county called downtown San Diego and its streets a “fecally contaminated environment” that has helped fuel San Diego’s current hepatitis A crisis. And frequently, sewage spills across the border through the Tijuana River, or comes up the coast from Mexico.

On this week’s San Diego Explained, Voice of San Diego’s Ry Rivard and NBC 7’s Monica Dean detail the region’s long-standing struggles with sewage.