When Good Passes Go Bad
To dredge or not to dredge? That is the question.
By Larry D. Hodge
Cedar Bayou is a narrow pass between the north end of San Jose Island and the south end of Matagorda Island. Its importance is far greater than its size indicates.
"The Texas Coast is unique in that it has barrier islands that close off bays from the Gulf," explains Ed Hegen, regional director of Texas Parks and Wildlife Department's Region 2 coastal fisheries division. "All the bays along the lower Texas Coast have or have had at one time a connection to the Gulf."
"The passes are critical to fisheries of all kinds," adds Larry McKinney, senior director for aquatic resources for TPWD. "The mixing of fresh water from river inflows with sea water entering the bays and estuaries through the passes creates differences in salinity levels that are necessary for completion of the life cycle of 90 percent of our recreational and commercially important fish. If you put a cork in the bottle and the developing fish can't get into and out of the bays, they can't complete their life cycle."
All along the Texas Coast, natural passes that facilitate the mixing of Gulf waters with freshwater inflows from rivers have closed for a variety of reasons. Cedar Bayou has closed and reopened in the past and appears to be in danger of closing again. A controversy is looming over whether the pass should be dredged to keep it open, or whether nature should be allowed to take its course.
Part of the problem is that nature no longer can take the course it followed for centuries. "Several factors have led to the closing of fish passes all along our barrier islands," says McKinney. "In recent years we have had diminished inflows from rivers, and the construction of the Gulf Intracoastal Waterway and dredging and deepening of harbors and channels to harbors have created more places for water to escape from the bays, reducing the hydrological pressure that used to force water through the passes and keep them open."
The answer seems simple: Dredge the channels to keep them open. But dredging is expensive and creates other issues, such as who pays, who benefits, where spoil is dumped and who compensates landowners if their land is eroded away as a result of the dredging. And dredging is only a temporary solution. "When you dredge, you create a deep hole in a shallow nearshore area, and the most likely place for sand carried by currents to settle is in that deep hole," says Hegen. "Maintained passes have to be dredged almost constantly to keep them open."
Human alteration of the hydrology of the coast means the passes no longer play as big a role as they once did, says Rollin McRae, wetlands conservation program leader for TPWD. "Reduced freshwater inflow means there is less freshwater in proportion to saltwater, and we may not need so many passes to bring in sea water," he points out.
Hegen agrees the issue of whether to dredge Cedar Bayou is not clearcut. "Data from our 25-year monitoring program indicate the bays are in good, healthy condition right now coast-wide," he says. "There is still a salinity gradient between the Gulf and the bays, and that maintains itself through the passes. But there is also an economic issue. Estimates are it will cost about $800,000 to dredge Cedar Bayou. From where will that money come? Will we continue to spend money to keep the pass open? If you are someone who wants to fish - and Cedar Bayou is a fantastic fishing area - you'll be in favor of dredging. But we don't know how the economic impacts and benefits of dredging balance out against the costs. We need to have all the interested partners involved - the Corps of Engineers, county governments, fishers - and make our decision based on the balance of those facts."
"Artificial maintenance of Cedar Bayou will be very expensive and long-term," says McKinney. "We need better cost-benefit data before we can tell if dredging is a good idea."