David Sunding, a University of California-Berkley economist, says the Environmental Protection Agency analysis of a proposed Clean Water Act rule is riddled with errors.

In his report “Review of 2014 EPA Economic Analysis of Proposed Revised Definition of Waters of the Unites States,” Sunding says EPA’s explanation of the rule and its costs and benefits are not realistic.

The rule looks to expand the “Waters of the United States” to include small, isolated wetlands, ephemeral drains and many ditches. According to Sunding’s report, EPA systematically underestimated the impact on affected communities and businesses when considering the new rule.

Sunding shows how EPA excluded costs, under-represented jurisdictional areas and used flawed methods to arrive at much lower economic costs of the proposed rule. Sunding’s report also notes that the lack of transparency in the report makes it difficult to understand or replicate EPA’s calculations, examine the agency’s assumptions or understand discrepancies in its results.

Sunding has concluded that the errors in the EPA’s analysis are so extensive as to render it useless for determining the true costs of this proposed rule. His report underscores the need for EPA to withdraw the rule and complete a comprehensive and transparent economic review.

“The EPA’s proposed waters of the U.S. rule is irreparably flawed from an economic standpoint,” said American Farm Bureau Federation President Bob Stallman. “The rule is also an end run around Congress and two Supreme Court rulings, and in their official comments, farmers and ranchers across the national are calling on EPA to ditch the rule.”

This rule will also have a huge impact on communities and businesses across the country, according to Stallman. He said it is not just businesses trying to expand that will suffer. This proposed rule would impact everything from local governments trying to start or expand infrastructure projects to community gardens.

“The rule will dictate land use across the United States,” Stallman said. “And EPA has not been forthright about the costs to our communities and businesses, including countless small businesses.”

Sunding prepared this report with support from the Waters Advocacy Coalition, which represents Americans involved in construction, real estate, mining, agriculture, wildlife conservation, forestry, manufacturing and energy, and includes the AFBF.