City Hall

Meet the Texas Heelsplitter Mussel, the Costly New Hurdle to the Trinity River Project

When Ron Kirk began pitching the Trinity River Project in the late 1990s, no one was thinking about the Texas heelsplitter or the Texas pigtoe, or the Mexican fawnsfoot, the smooth pimpleback, or the Texas fatmucket. There was no real reason to. Back then, the species were sufficiently abundant that they didn't merit state or federal protection.

That changed in 2010, when the Texas Parks and Wildlife Department listed those and 10 other freshwater mussels species as threatened. The mussels are an important part of aquatic ecosystems, the department explained, providing food to a variety of insects and animals. Habitat loss, excessive harvesting, and poor water quality all contributed to a decline in their numbers.

More to the point, the move helped forestall a listing by the U.S. Fish and Wildlife Service that would mean stricter rules and higher penalties, neither of which would be good for the Texas economy. Or so the argument goes. The federal agency's decision is still listed as being "under review."

The state listing did carry some penalties, making it a misdemeanor to kill or collect the bivalves. That's an easy enough rule for the average Texan to follow but it gets a bit harder when you're a large business or government aiming to build things -- like, say, a signature bridge -- in or near the state's rivers. Cue costly and time-consuming environmental surveys and, in instances where mussels are discovered, removal efforts.

The elements of the Trinity River Project that have already been built, like the Calatrava and the standing wave, were already completed or far enough along by the time TPWD made its ruling that they escaped the new rules. But now, as the city prepares to move forward with the transformation of the Continental Avenue Bridge into a linear park, the city's must face the Texas heelsplitter and Texas pigtoe, the two threatened species that populate the Trinity.

There's a good chance the Continental project will disturb exactly zero protected bivalves. The heelsplitters at least are concentrated in the northwestern corner of Dallas County, and even there there have been maybe a dozen observations. But the city has to check, which is why the City Council will vote Wednesday on whether to pay Halff Associates $147,512 to "investigate, identify and potentially relocate" the mussels.

That's a drop in the bucket in the grand scheme of the multi-billion-dollar project. But if it's something that comes up whenever the city gets ready to build wetlands or toll roads or other bridges, it can add up. We have an email in to assistant city manager Jill Jordan, who oversees the project, to see if or how this factors into the city's long-term thinking.