It’s the season for outdoor art. Memorial Day is upon us, and who wants to be cooped up in some dusty museum or gallery? After visiting our priceless Olympic Sculpture Park, more people should keep walking north into the older, city-owned Myrtle Edwards Park, which continues along the shoreline to Interbay. Not only does it contain the city’s most significant piece of public art, Michael Heizer’s 1976 Adjacent, Against, Upon, but a newer, smaller piece that deserves closer scrutiny. Cut through a berm at a King County sewer pumping station, stainless-steel plates flank Laura Haddad‘s 2003 Undercurrents, an etched-metal sluiceway aimed into Elliott Bay, ringed by a pleasant circular plaza. Added in ’09 to help disguise a mechanical vault for the giant $140 million project beneath, the berm’s plates read like a wall of hieroglyphics or blueprints for the underground apparatus. Though, certainly, no mechanical engineer would rely on them. The curlicues and diagrams meander in a pleasingly nonsensical way; printed on the steel are exploded gears and pocket change, a Magritte pipe, valves and buckets, electrons and musical notes—like a Monopoly board designed by Rube Goldberg. Below, we know, lies the Denny Way/Lake Union Combined Sewer Overflow (CSO) Regulator Outfall, connected by a 6,200-foot tunnel all the way to SLU! When our sewers are overwhelmed by the weather, storm- and wastewater are belched out into the bay, far offshore. Run your fingers over the steel diagrams, and you can almost hear that rumble.