by Dave Wilson. (Wilson is the public outreach coordinator for the Maryland Coastal Bays Program).

As spring approaches and pool owners get set to drain their summertime havens for replacement with new, clean water, there are a few legal and ethical precautions that should be heeded before advancing.

For swimming, pools are nice for people. But for wildlife and the bays, the chemicals and metals used for disinfecting pool waters can be deadly to aquatic organisms and very harmful when they percolate to groundwater and into drinking water supplies.

Disinfectants and algicides are primary culprits and are very toxic to fish, shellfish and crabs. Whether dumped directly into the bays or in a stormdrain miles away, these chemicals invariably make their way to the coastal bays. Some of these materials, such as copper and silver, can also cause drinking water problems whether in the form of birth defects or mental dysfunction. Standards for the discharge of water containing copper and silver are very stringent.

Acidity or pH is regulated for cleaning discharges because acid is routinely used in this process. The discharge of acidic wastewater to surface waters can kill amphibians and aquatic life, and discharges to ground water can damage the potability of the water supply. In Ocean City, dirty water, wanton hoses and even flooded roadways from discharges have been a problem.

Owners of public pools and spas must have a city and state permit to discharge pool and spa water. The permit authorizes the discharge of pool or spa overflows, drainage, cleaning wastewater, and filter backwash. The permit requires quality control of wastewater by the best available treatment or pollution prevention technology and regulates residual chlorine, bromine, copper, silver, PHMB, other disinfectants, algicides, pH, suspended solids, and turbidity.

Pool owners discharging only to sanitary sewer are not required to register under this permit, but must receive permission to discharge from the operator of the sanitary sewer, and meet any conditions that operator imposes.

Private single family pool owners can minimize the potential impacts of discharges by::

1. Maintaining the pool filtration system
2. Covering pools when not in use
3. Not draining or lowering water levels in pools until disinfectant levels are nondetectable
4. Allowing chlorine to dissipate over a few days (Sodium thiosulphate or sodium metabisulfite can reduce chlorine levels quickly)
5. Making sure water used to acid wash pools is neutralized prior to discharge (Soda ash can be used to keep the pH between 6.0 and 9.0 before discharging)
6. Confining backwash water discharges to the ground, vegetated or wooded areas rather than storm drains, bays or ditches
7. Draining pools slowly, using a low-volume pump or siphon

Discharges from swimming pools and spas, though common and often small, can harm aquatic life and groundwater drinking supplies. However, small steps can help diminish these problems.

A copy of the general permit may be obtained from the Wastewater Discharge Permit Program, Maryland Department of the Environment, 118 Washington Blvd., Baltimore MD 21230.
Call Patsy Allen at (410)537-3625 or e-mail pallen@mde.state.md.us.

In Ocean City, call Rich Mason at 410-289-8861 for permit information.For more general information call Gail Blazer at 410-289-8825.