Life deserting loop canal
There is something fishy happening in the Bethany Beach Loop Canal — or rather something fish-less.
For about six weeks, the manmade canal has had significantly low dissolved oxygen levels. That means that, for fish and other aquatic life in the water, it is getting harder and harder to get the oxygen they need to survive. So, it seems many have simply left.
Although this is an event that happens every summer, according to officials at the Delaware Department of Natural Resources and Environmental Control (DNREC), the amount of time that has passed since the first low level was recorded is something new.
“Every summer, certain areas of the Inland Bays — especially the least-flushed areas — have chronic low dissolved oxygen levels,” said Roy Miller of DNREC, “and the Loop Canal fits the bill in that regard.”
It’s a phenomenon that 30-year Bethany Beach resident Dean Phillips first noticed this past June.
“About a month and a half ago, I started to notice there were no small fish, no crabs, no fingerlings. I thought it was a little odd, but I packed it away. Then I noticed that there was nothing — no birds, nothing… I have lived there for 30 years, and never seen anything like it.”
Dr. Ed Whereat is the program coordinator for the University of Delaware Citizen Monitoring Program. He has been monitoring the site, as well as several others in the area, and agreed that there seems to be a real phenomenon happening in the Loop Canal.
The Citizen Monitoring Program trains and then utilizes volunteers to conduct water sampling, helping to collect important information about harmful algae blooms. They also take water samples to study dissolved oxygen levels, nutrient concentrations, water clarity, bacteria levels and other environmental data from assigned monitoring sites throughout the Inland Bays watershed.
“Although this is not dramatically new, the extent is longer,” said Whereat. “I would attribute the cause of the problem there to chronically low dissolved oxygen rather than toxic algae, although persistent algae blooms and their subsequent decay are the cause of the low oxygen,” he explained.
The two Loop Canal sites that the Citizen Monitoring Program samples are admittedly the bottom of the barrel, so to speak, as regards to tidal flow — something that is needed to keep adequate dissolved oxygen levels in the water.
“This canal system is quite isolated from tidal flow, and the sites where we measure are at two dead ends where conditions are probably the worst in the system,” said Whereat of the sites at the end of the canal between Route 1 and Pennsylvania Avenue and a finger canal just north of St. Ann’s Catholic Church.
Whereat noted that dissolved oxygen is measured in parts per million (ppm). He said they have seen numbers in the Loop Canal peak at 3 ppm and dip below 1.5 ppm, with numbers above 4 or 5 representing a “healthy water body.”
But since those numbers in the Loop Canal have dropped gradually, there have been no fish or crab kills to speak of, just simply a migration of the aquatic life, Whereat said.
“The bottom line,” said Whereat, “is it is a very restricted tidal flow, very stagnant. There is nothing to do in the short term.”
Both Whereat and Miller agreed that, generally speaking, excessive nutrients and excessive water temperatures could factor into the low oxygen levels, as does the restricted tidal flow. As for a remedy, there is no easy one, they said.
“There’s nothing palatable,” said Miller, “besides filling it in and letting it revert back to the natural system, which doesn’t appeal to anybody.”
Whereat hypothesized that some would say dredging would help solve the problem, but he noted that the north end of the Loop Canal, to where it joins the Assawoman Canal, has been dredged already.
“The dredging on the Assawoman Canal doesn’t appear to have caused enough tidal flow to prevent this sort of thing from happening,” he said. “Some smaller marinas have circulators, or little fountains or bubblers, to improve conditions. But it would take a lot to oxygenate the Salt Pond.”
The Loop Canal travels parallel to Route 26 and culminates at the mouth of the Salt Pond and at the “loop” next to Pennsylvania Avenue in Bethany Beach, where a historical marker describes the way early Bethany Beach vacationers got to town via the canal system.
For more information on the Citizen Monitoring Program or to view the low dissolved oxygen reports from June and July, visit http://citizen-monitoring.udel.edu online.