The thin blue line is painted on sidewalks and bridge supports, climbs up onto brick walls and relaxes in the park. It’s also broken into sections, appearing to duck into storm drains, slip down side-streets, and leap across intersections.

Like a giant spool of yarn knocked to the floor, unwound, and batted about by mischievous cats, you’re likely to come across Watermark somewhere in the middle and wonder what’s going on. The piece–part large-format public artwork and part community-engagement project–is doing its thing right now, in Millvale.

The line follows a loose path and it’s no hurry to get anywhere. It starts, or maybe it ends–your choice–at the big concrete support for the north end of the 40th Street Bridge in Millvale’s Riverfront Park. From there, it winds a jagged, herky-jerky route out along the jersey barrier retaining wall by the park’s bicycle trail, crosses the town’s busiest intersection, and winds its way up through the Grant Avenue business district. The long blue strand finally concludes in a glorious, unruly tangle in the little Grant Avenue Pocket Park at the top of the street.

The Watermark line is around two-thirds of a mile long, as the crow flies, and has the good sense to meander through much of downtown, effectively becoming a guide to a sort-of Tour d’Millvale. Along the way, it winds past Cousin’s Lounge, the upholstery shop, library, and Yetter’s Candy.

This record fiend can’t visit Millvale without poking his black plastic-sniffing schnoz into Attic Records, but the blue line decided to skip to the other side of street to avoid such temptation. Clearly not into model railroading or macaroons, the end of the line happens just before rounding the corner to Esther’s Hobby Shop and Jean Marc’s French bakery.

Watermark is the work of Ann Tarantino, one of six artists participating in Neighborhood Allies’ Temporary Public Art Pilot. Tarantino tells us the goal of the piece is to “connect the community to water–to link the riverfront to the rest of town.” The GAPP park, along with other buildings in downtown Millvale, was built right on top of the Girty’s Run stream that can be seen flowing through its raised concrete flood walls both above and below the business district. Its influence is felt–if not expressly stated–by the shape, color, and general direction of the blue line.

It’s a tall order, connecting Millvale town to its riverfront. Anyone who’s ever attempted to negotiate the ugly six point intersection where Grant and E. Ohio join the Route 28 on-ramps as either pedestrian or cyclist knows how harrowing the experience can be. Will a thin, painted line actually get riverfront bicycle-riders and cookout cornhole-tossers up to Panza Gallery or happy hour beer-drinkers down to the river? This blogger could only guess…but it got him to follow the trail all the way, just to see where it would go.

The project is not yet complete. Tarantino informs us the blue line itself will still have some more painting and “connectivity” points added, but the major additions will be descriptive signage at both ends and an installation/”final experience” to be installed in the GAPP park. The Orbit will have to wait to check that out just like everyone else, but we were teased that it will involve both sound and light and should be installed later this Fall.

We talked to a few folks sitting on front stoops along Grant Ave. during an otherwise entirely vacant, bright sunny Labor Day holiday and it’s obvious the explanatory signage will be a benefit. “What does it mean?” said one befuddled hanger-out. His buddy: “It don’t mean nothin’.”

Unlike these critics, however, The Orbit is perfectly happy to live in a world without all the answers and can therefore take a more piqued approach to the abstract project. After a couple visits now, we find the loose, playful, follow-the-blue-line curiosity to be appealing on a number of fronts and begs several enticing questions: Where is it going? Who did this? Why is it here?

Hopefully having the answers to some of these in the convenient electronic format in front of them now won’t dampen our readers’ interest in checking out Watermark for themselves. If so, that would be a shame. The way to see the piece is on your feet, walking the cement and brick sidewalks of Millvale, headed for some of P&G’s mind-melting, Michelle Obama-approved hotcakes or a piece of Dutch apple pie from the legendary hands of Frank Ruzomberka at the Grant Bar.

Is Watermark great art? I don’t know about that. But it’s a simple, low-tech (at least, until we get that sound and vision experience), and effective conversation-starter. We think it also succeeds at making any side-walker or stoop-sitter both active participant in and art critic of an odd little curio traipsing through their borough. Those are interesting challenges to rise to and we had a fine time chasing its long blue tail.

Love it or hate it, the whole thing will disappear in 2019. Watermark, like the other Neighborhood Allies projects in this series, is temporary. It is scheduled to have just a two-year lifespan. Tarantino tells us the line was created with a type of paint that can be rinsed with a cleaning solution and power-washed away like it was never there at all.

Watermark is a project sponsored by Neighbor Allies’ Temporary Public Art Pilot and the Office of Public Art. It is funded by Heinz Endowments and Hillman Foundation and supported by community-based organizations Millvale Community Development Corporation, Millvale Community Library, and the Society to Preserve the Murals of Maxo Vanka.

Tarantino will continue to update news of the project at her website. You can follow her on Instagram at @anntarantino.