Some have fled the threat of future floods. Some have returned to rebuilt homes. And others are still waiting.

Whether you’re cleaning your kitchen after a big meal or finishing a painting project, it can be tempting to pour just about anything liquid—or sometimes even solids—down the drain.

Take a trip back in time at Old Town San Diego State Historic Park, an approximately mile-long and half-mile-wide area contained stretch of preserved or reconstructed shops and houses on the ...