The Iowa Department of Natural Resources has released its new list of "impaired waterways" — meaning lakes or river segments that fall short of at least one water quality standard.

This time 750 of the 1,378 waterways checked fell short of one or more standards. The monitoring is part of a U.S. Environmental Protection Agency system that by definition underestimates the number of waterways with problems. For example, two of the most important pollutants in Iowa — phosphorus and nitrogen from crop fertilizers and other sources — aren't even included because the state has no standards for them.

In the past, the state's own staff has said the number of impaired waterways actually should be 10,000 or more.

The state typically soft-pedals that rising number in the polluted waterways list, and notes that conservative standards mean the waterways might not be in trouble at all.

"The increase in impaired waters does not necessarily mean that the water quality in the state is worsening; it often is a reflection of the additional monitoring we are conducting," Roger Bruner, supervisor of the DNR's water monitoring and assessment section, said in a statement.

Environmental groups don't buy it, noting that the state's limited monitoring and lack of standards for some key elements mean that the list is shorter than it should be. They also note that the growing number of entries shows the state continues to fight pollution problems, particularly from farms.

"The only way we'll begin to clean up Iowa's water is if the Legislature passes meaningful, enforceable rules and regulations and make polluters pay the cost," said Barb Kalbach, a member of Iowa Citizens for Community Improvement, a nonprofit organization that has fought agricultural pollution.

The DNR will accept public comments on the draft list through May 29. Write to:

Iowa Department of Natural Resources
Attn: Dan Kendall
Water Quality Monitoring & Assessment Section
Wallace State Office Building
502 E. Ninth St. 
Des Moines, IA 50319