by Carol Cain, Technical Coordinator for the MD Coastal Bays Program

Recently the Maryland Coastal Bays and Delaware’s Center for the Inland Bays joined forces to convene a workshop on the problems associated with dead end canals. More than one hundred participants gathered to discuss the scientific and technical components of canals including how the canals are engineered and what are the possible solutions to prevent pollution and associated algal blooms and fish kills.

Many homeowners’ were unaware that their property had originally been a marsh. Before the mid 1970’s contractors could dig out canals in the marsh and use the adjacent spoils as upland for home sites. Often the canals were deeper than the bays they were connected to and this has prevented proper flushing of the waters in the bottom of the canals. High levels of nutrients and toxic chemicals have been found to accumulate along the bottom thus creating an ecological dead zone. A study conducted by EPA has revealed that 75 percent of the Coastal Bays canals have harmful chemical levels. Additionally, studies of bottom oxygen levels within these canals have revealed that during summer months oxygen levels are consistently falling below the state’s minimum standard of 5 parts per million. In fact, more than half (55%) of the canals tested had less than the 5 ppm, and 30% had concentrations less than 2 ppm. Additionally harmful algal blooms, which are capable of human and aquatic health impacts have been discovered in these canals, and may have contributed to the demise of 15,000 menhaden in a Cape Isle of Wight canal in June 2002. In August of 2001, the State’s largest documented fish kill, 3 million silversides, occurred in a West Ocean City canal.

Other issues include shoaling and sedimentation, which impedes navigation. Dredging canals periodically has been the only remedy to date. However, the permit process can be cumbersome and finding a suitable spoil location is becoming increasingly difficult to access. Additionally, large mats of macroalgae, the result of the increase in nutrients within the water, are fouling boat propellers and present an odor nuisance when the algae decompose.

New canals are no longer permitted, however the issues in existing neighborhoods remain to be addressed. Dredging and retrofits to promote circulation are certainly a possibility, albeit temporary and expensive. The best practices to adopt are those, which will prevent further degradation in the first place. This would include directing stormwater away from the canal to prevent increasing the sediment and nutrient levels. Similarly, do not allow grass clipping, pet waste, fish carcasses, or other garbage to foul your canal. Try using nontoxic anti fouling paint on the bottom of your boat. Substitute vinyl for pressure treated bulkhead materials, which contains toxic chromium, cadmium, and arsenic. And where practical, remove the bulkheading and plant native grasses and shrubs which absorb wave energy rather than deflecting it which results in scouring and shoaling.

The Dead-End Canal workshop was an important step in reaching out to residents who live on the water and are best suited to observe and prevent further degradation. Our goal is to educate and implement changes to prevent pollution and put the power and responsibility to do so in the hands of those communities and residents most affected.