Four Unsung Spots #3: Highland Park Seasonal Pools

July 31, 2009 by Melissa McMasters

What do you get when you cross a lawnmower with a huge, completely flat field of grass that just happens to be located at the foot of a very steep hill?

The lawn in February 2006

If you answered "a maintenance nightmare," you'll appreciate one of the Conservancy's lesser-known capital projects, known as the Highland Park seasonal pools. Once a large patch of grass that regularly flooded and contributed to water runoff onto Washington Boulevard near its intersection with Allegheny River Boulevard, this area is now a wetland habitat that's unique in the Pittsburgh park system.

Much like the Schenley pool meadow that we covered as our first unsung spot, the seasonal pools weren't an original part of our Regional Parks Master Plan, instead arising out of a problem that more or less demanded a solution. Several years ago, then-Mayor Tom Murphy commissioned a new trail in Highland Park to provide a link between the park and the rest of the citywide trail system. The trail was originally slated to run across the lawn area, but the Parks Conservancy saw its construction as an opportunity to combat the woody invasive species that were aggressively taking over the bottom of the slope.

The completed seasonal pools

So instead of creating a trail on a lawn that regularly flooded, the City's Department of Public Works Construction Division routed the trail partially through the woods, creating a more unique experience for cyclists and hikers. The team created basins, culverts, and outfalls so that the energy of the water coming down the hillside would dissipate, reducing flooding. Along the south side of the trail, the seasonal pools (also called vernal ponds) were created to catch the water. As Phil Gruszka, our Management and Maintenance Director, puts it, "That's what that area wanted to be anyway," but instead of being regularly mowed, now it could collect water and provide habitat. In 2006, the trail and the pools were completed.

The Parks Conservancy began sowing native seed mixes all around the ponds, instantly laying the foundation for a biodiverse habitat. Now instead of flooding a lawn full of grass whose roots aren't deep enough to soak it up, the water goes into the wetland, filling the pools and infiltrating via the deep roots of dozens of different types of wildflowers.

Wildflowers spotted at the seasonal pools.  Top: Bloodroot, ironweed, and black-eyed susan.  Bottom: Blue vervain, buttercup, and butterfly weed.

The wildflowers are striking, especially this time of year when the black-eyed susans, ox-eyes, and bergamot create a sunny spectacle dotted with pale purple. But what's even more encouraging is the amount of animal species that have been spotted in this previously non-existent wetland habitat. Some birds, such as the red-winged blackbird, prefer to live in wetlands, and there is a large colony of them that inhabits this space. Dragonflies and damselflies buzz around the water, lighting on cattails. Other species that have been spotted include great blue herons, snakes, slimy salamanders, red tail hawks, and raccoons. The pools have been a true success story in terms of bringing biodiversity into the parks.

Volunteers planting bald cypress trees

They've been a success in other ways too, including as a site of community involvement. In 2007 a group from the Girls Math and Science Partnership came out several times to do monitoring of water levels and quality. We've had several cleanup events where we fished litter out of the pools that had run off the hillside. And ecological restoration efforts on the site have been continual: the hillside had a number of invasive trees (mostly Norway maple) that have been removed, and new trees have been planted each season. This spring we kicked off our Home Runs for Trees initiative by planting several bald cypress trees in the area between the pools and Washington Boulevard. Now we're focused on keeping all the new trees watered and healthy so that we can add biodiversity to the tree canopy in addition to the wetland.

So the next time you head over to the Washington Boulevard bike track to catch a race (or participate in one!), take a few extra steps and check out this relatively new habitat that's bringing all kinds of new creatures into the park. And don't forget to bring your camera, just in case you spot a turkey hiding among the wildflowers!

(Wildflower ID thanks to this great site!)

The plants have really sprung up around the pools; heres the same view from April 2007 and July 2009.

Ecological Restoration, Highland Park, Parks Management