Branstad, who was in Nevada speaking about a county broadband initiative on Thursday, has faced criticism from environmental activists over his opposition to Des Moines Water Works’ move to sue three rural counties in northwest Iowa over nitrate pollution in the Raccoon River, a major source of Greater Des Moines tap water. The board gave 60-day notice of its intent to sue in federal court under the Clean Water Act, contending that drainage ditches controlled by Sac, Calhoun and Buena Vista counties amount to point sources of pollution.

Nitrate occurs naturally and comes from farm fertilizer. At high levels, it causes a blood condition that suffocates infants, and it has been associated with a variety of cancers.

The Water Works board called decades of voluntary efforts by farmers a failure, and noted nitrate readings several times the health limit in the Raccoon system. The tap water is safe, but it requires expensive treatment to make it safe, the board noted. Water Works wants the pollution reduced, perhaps by regulating farm operations in the same way that other industries are.

Agriculture groups said the lawsuit will delay pollution-cutting efforts. They add that voluntary work by farmers and cooperating agencies have reduced nitrate in areas that have buffer strips, grassed waterways and other conservation practices called for under the Iowa Nutrient Reduction Strategy.

Branstad favors building on the state’s voluntary approach.

The Des Moines Register on Sunday weighed in on the broader implications of the Water Works lawsuit.