In a recent letter to the editor Richard Rothschild's argument that state officials' policy on septic systems is based on politics rather than science doesn't square with the facts ("Carroll commissioner: MDE is cooking the books on septics," Dec. 4). The Maryland Department of Planning and the Maryland Department of the Environment used the best available scientific data modeling available in our analysis.
Typical septic systems release 23.2 pounds of nitrogen from wastewater per household into the environment. That's roughly 10 times the nitrogen contributed by households served by wastewater treatment plants.
Development based on septic systems also produces more pollution in storm water runoff than houses using sewer systems. This is primarily because lots using septic systems are typically much larger — 2 acres or more on average — not because fertilizer is somehow unevenly counted against septic development, as the commissioner asserts. And none of the state calculations include nitrogen pollution coming from outside Maryland, as he also contends.
Over the next 25 years, new development in Maryland using septic tanks will account for a quarter of all new households but it will produce two-thirds of the nitrogen pollution from new development that winds up in Maryland's rivers and streams. And unlike other sources of nitrogen such as agriculture, where farmers are working hard to decrease the environmental impact, the amount of pollution from septic wastewater and storm water continue to increase.
Ignoring the problem won't make it go away. Mr. Rothschild's panel of experts, it should be noted, also concluded that waste from stray cats and dogs in Baltimore are a major cause of bay pollution and that global warming, if true, isn't bad because more people like to live in warm climates.
The commissioner can rely on whomever he chooses, but his experts won't have to answer to future generations about how and why Maryland failed to protect its bays, rivers and streams. The O'Malley-Brown Administration is determined that question will never need to be asked.
Richard Eberhart Hall and Robert M. Summers, Baltimore
The writers are, respectively, the secretaries of the Maryland Department of Planning and the Maryland Department of the Environment.