What if the dead zone that plagues the Chesapeake Bay could be eliminated now, not years down the road — and at a fraction of the billions being spent annually on restoring the troubled estuary?
Fanciful as it sounds, Dan Sheer figures it’s technically doable. Whether it’s the right thing to do is another question. Bay scientists are wary of potential pitfalls, but some still think it’s worth taking a closer look.
Sheer, founder and president emeritus of HydroLogics, a Maryland-based water resource consulting firm, has suggested that the oxygen-starved area down the center of the Bay could become a thing of the past if enough air could be pumped into the depths and be allowed to bubble up through the water.
“It pretty much gets rid of the problem,” he said during a recent presentation to scientists at the University of Maryland, Baltimore County. And it’s not just him saying that. The federal-state Chesapeake Bay Program ran his oxygen-bubbling calculations through the computer model it uses to simulate water quality in the Bay, and the preliminary results appear to back him up.
The dead zone, as it’s called, is produced when algae blooms fed by excessive nutrients in the water die and decay, consuming the dissolved oxygen that fish, crabs and shellfish need to live. This zone of low to no oxygen forms near the bottom in the deep trough down the center of the Bay every spring and grows through summer, until finally receding in fall when algae growth ends.
The Bay Program has been laboring since the 1980s to reduce nutrient pollution and raise dissolved oxygen levels enough to eliminate the dead zone, but the effort has been costly and challenging. The region missed two earlier cleanup deadlines and is now working toward another target date of 2025, when all projects and programs needed to meet nutrient reduction goals should be in place. That’s looking increasingly unrealistic as well.
Aerating the Bay would be quicker, Sheer contends, and potentially less expensive. His idea: Lay 16 pipes across the deepest part of the Chesapeake at 5-mile intervals from Maryland’s Bay Bridge to the Potomac River, with a series of openings in them to release streams of tiny air bubbles. The oxygen in the bubbles would dissolve into the water and help sustain aquatic life.
Sheer isn’t the first to suggest bubbling the Bay like an aquarium. It’s been brought up repeatedly over the last 30 years, only to be dismissed as unworkable and inordinately expensive — harebrained, even.
In the late 1980s, Maryland tested floating aerators in a cove off the Patuxent River, but gave up after they produced a barely detectable change in oxygen near the bottom. In 2011, the nonprofit Blue Water Baltimore, in partnership with a consulting firm, placed a small aerator in Baltimore’s harbor, with similar results.
Aeration has been used with some success elsewhere in freshwater lakes and reservoirs that suffer from nutrient pollution. And, it has helped water quality in some rivers, such as the Thames in the United Kingdom.
Pumping air into big open bodies of tidal water is more problematic. Scientists in Sweden and Finland have looked at and tested aeration as a possible remedy for severe algae blooms in the Baltic Sea. But they’ve held back from trying it on a large scale, in part because of uncertainty about its costs and effectiveness.
Given that history, reaction to Sheer’s proposal has been mixed. . .
|Aerators in Rock Creek|
Doing it in the Bay mainstem would likely cost much more. Working with scientific colleagues, Sheer has estimated that it would cost $10 million–$20 million to install the piping network, bubble diffusers, air compressors, oxygen generators and other equipment. To run it would take another $11 million a year, by their estimates, with much of that spent on electricity to power the air compressors, pumps and other equipment.But have they applied the 3 fold correction necessary to account for the difference between what a PhD thinks something should cost, and how much it actually costs?
Aside from the technical issues (where are the air pumps, what powers them and who pays, well, besides us) and the costs, I have one substantial objection to this proposal. Setting up an aeration system like this one would, necessarily, bring up nutrient rich bottom water to the surface, in all likelyhood setting off an enormous algae bloom in the mainstem of the Bay, which is already plagued with algae blooms, which is how we got here in the first place. And there's no assurance that they would necessarily be benign algae blooms? Well, there's only one way to find out