Maine’s senators are expected to cast decisive votes on a water conservation program that would improve irrigation for blueberry growers and ease the pressure on endangered wild Atlantic salmon.

The farm bill provision would give farmers money to improve water storage or irrigation systems, which would leave more water in rivers where endangered wild Atlantic salmon swim in Maine.

Blueberry growers tap rivers during dry weather – a time when the fish also need the water.

Western Republicans opposed to the provision say it would give federal officials jurisdiction in water allocation – a role that they say should rest entirely with state officials.

An amendment from Sen. Michael Crapo, R-Idaho, would remove the program from the farm bill.

The votes on the provision could come this week. Nearly all of the 50 Democrats in the Senate support the water conservation program and nearly all the 49 Republicans oppose it.

A spokesman for Sen. Olympia Snowe said she is likely to support the provision Crapo wants removed. A spokeswoman for Sen. Susan Collins said Monday that she had not decided.

The water conservation provision is part of the $73 billion farm bill, which mostly provides crop subsidies for wheat, corn and rice growers. The water provisions allocates $375 million over the next five years for conservation.

No estimate is available for how much each state would receive because that will depend on how many farmers participate. But total conservation provisions in the bill guarantee at least $12 million a year in new funding for Maine.

The conservation provisions aim to keep more water in rivers by encouraging farmers to switch to less thirsty crops, paying farmers to install storage ponds or drill wells and enabling states to lease water from farmers.

Western Republicans argue that the water provisions expand the Endangered Species Act and put farmers at risk. They contend that if farmers lease the government their water rights temporarily they could be at risk of losing them permanently if endangered fish become dependent on the additional water.

Idaho Gov. Dirk Kempthorne wrote a letter to the Senate saying the federal provision is inconsistent with water laws of 18 Western states.

But Sen. Harry Reid, D-Nev., who wrote the water provisions, said state governments would hold water rights and leases, protecting farmers. He planned to offer an amendment explicitly prohibiting the federal government from buying or leasing water.