Two Arizona Tribes are suing the federal government after President Donald Trump repealed Obama-era regulations defining the scope of the protections of the Clean Water Act.

The action eliminates federal oversight of pollution into small streams and washes as well as adjacent properties.

Plaintiff attorney Stuart Gillespie said these rules are necessary to carry out Congress’s original intent to protect the country’s navigable waters.

“In order to protect the navigable waters of the United States you need to protect the tributaries and headwater streams that provide the lifeblood that sustains those downstream waters," said Gillespie.

On the other hand, David Godlewski, president of the Southern Arizona Home Builders Association, says his members support the administration’s move saying the prior regulations were unnecessary and expensive.

“That drives up the cost of land development and ultimately the cost of housing. And it makes housing less affordable," said Godlewski.

The lawsuit is asking a judge to set aside the new changes. But a spokesperson for the EPA defends the changes saying they strike a balance between state and federal jurisdiction and end the confusion that has existed for decades.

Even that is problematic, according to challengers, because it defines "typical year" meaning when precipitation and other climatic variable are within the "normal periodic range ... for the geographic area."

Only thing is, the lawsuit states, the rule doesn't define what is "normal periodic range" and doesn't provide guidance on what is the relevant geographic area.