Anyone who has walked, run, ridden a bike or driven around Portland’s Back Cove over the last year has seen heavy equipment involved in some serious excavation.

That’s part of the city’s sewer separation program, which will prevent polluted storm water from flowing into Casco Bay.

But those same joggers, walkers, bikers or drivers might miss a smaller project that has some of the same goals.

On the north side of the parking lot on Baxter Boulevard is a newly landscaped depression that is worth taking a moment to consider.

It’s a “rain garden” designed to be a low-maintenance way to keep polluted runoff out of the bay. The demonstration project put together by the city and a number of local businesses is designed to give other property owners some ideas for a low-cost way that they can protect local streams and watersheds from becoming unintentional storm water sewers.

The Back Cove rain garden uses plants and soil to retain and clean storm water that has been polluted from spilled gasoline, anti-freeze or uncollected dog poop, before it runs into the cove.

The city is engaged in a number of water quality improvement projects around the Capisic Brook, which drains water that runs off rooftops and paved roads and parking lots into the Fore River and Casco Bay.

Major construction projects can only do part of the job. Use of low-tech landscaping, like the rain garden, not only looks nice, but can also make a big difference.