County Executive John R. Leopold asked Gov. Martin O'Malley yesterday to halt plans for a fly ash dump along the Anne Arundel County-Baltimore city border.

Leopold asked the governor in a letter to block the plan by Constellation Energy. He wrote a similar letter on Monday to state Environment Secretary Shari T. Wilson.

"Although the landfill itself is located in Baltimore city, the site is less than 1,000 feet from its border with Anne Arundel County and in close proximity to the surface waters of Swan Creek," Leopold wrote in the letter to...