The public can now weigh in on efforts to deal with the scourge of Idaho's groundwater - nitrate.
The Idaho Department of Environmental Quality is taking public comment through July 30 on a draft management plan for the Minidoka Nitrate Priority Area, first formed in 2002.
The area is one of 25 across the state formed to combat nitrate levels that near or exceed the federal and state standard, 10 milligrams per liter of groundwater. A form of nitrogen, the substance is possibly linked to health issues in humans and animals and serves as a sign of other water quality problems, said John Bokor, DEQ regional drinking water protection coordinator.
State officials have determined that nitrate is the most widespread, preventable groundwater contaminant in Idaho, where residents get 95 percent of their drinking water from the ground. Keeping it out of the ground is a challenge, and removing it is even harder.
"It'd pretty much be impossible to clean it out at this point in time," Bokor said.
Irrigated farmland - the main land use in the Minidoka priority area - confined-animal feeding operations, septic tanks and nutrient-rich wastewater used on fields are the main sources of nitrate, Bokor said. But the ever-moving aquifer and porous soil make it hard for scientists to track exactly how nitrate enters the groundwater. Even wells just across the road from each other can test differently, he said, based on their construction and how deep they go.
The solution, Bokor said, is to try to clean up practices on the surface and stop further pollution of the aquifer. The Minidoka plan was developed over a year and a half by an advisory committee that included the MinidokaSoil Conservation District, Idaho State Departmentof Agriculture, Idaho Department of Water Resources, local residents and several other government agencies. It relies on education and voluntary changes in best management practices to reduce nitrate deposits.
Considering how slow groundwater can move, it's not an easy process.
"This has been more than 50 years in progressing the other way," said Brent Stoker, a board member of the West Cassia Soil and Water Conservation District. "It will probably take as long to decline it as to get there."
The agencies and other groups involved will annually review progress on the plan's goals and any new data from state monitoring stations, at least for the first few years. The soil conservation district will be in charge of compiling each review, with the first one scheduled for fall 2008.
Twin Falls, a large area second only to Weiser on thepriority map, received its plan more than five years ago, Bokor said. So did Cassia, third on the list.
DEQ is in the process of reevaluating the Twin Falls plan, which has met with mixed success during the past few years, Bokor said. The revised plan may focus more on promoting the need for voluntary steps to landowners.
"We need to work harder at getting things implemented that are written into the plan," he said.
Recent DEQ open houses in both Cassia and Minidoka counties gave those with private wells a chance to test their water. And Cassia officials are in the third year of a project aimed at measuring just how much nitrate is leaking into the soil from irrigation sprinklers, Stoker said.
Spread across 6,000 acres of farmland, the project uses probes that sink four feet to measure whether current irrigation practices are adding at all to the current problem.
"So far, the indication is that we are not, so far as we can see," said Stoker, who farms and owns cattle, and participates in the project.
Much of the contamination in the Mini-Cassia area is in a "perched" aquifer close to the surface that formed as a result of flood irrigationpractices decades ago, Stoker said. Unlike much of the Magic Valley, there are no tunnels or underground streams to keep the water moving. Therefore, he said, the nitrate just sits there.
A new grant, Bokor said, will allow DEQ and the Cassia soil conservation districts to track pharmaceuticals and other contaminants that could pinpoint where the nitrate is coming from. Synthetic fertilizers would lead them to farm fields, while other chemicals could indicate sewer systems, Stoker said. Even with the grant, it will take some time to prepare and interpret the studies.
"It's two or three years before we're going to be able to make sense out of some of those tests," Stoker said.
Today, Bokor is in Boise, helping to re-evaluate nitrate priority areas. One area in the Hagerman Valley may be added to the list. A small area around Bliss currently ranks last.
Stephen Thompson, Natural Resources Conservation Service district conservationist for Gooding and Camas counties, said he wasn't sure which area around Hagerman DEQ was studying. But scientists have had a hard time tracing nitrate near Bliss, he said, especially since agricultural producers in the area have already taken steps to reduce the problem.
A new theory, he said, involves heavy applications of animal waste or fertilizer on farm fields. The nitrate in those, he said, could possibly seep into the soil and travel sideways into wells, just feet below where many of them are buffered from such an event.
"That's a hypothesis at this point," Thompson said, adding that scientists have yet to start tracking excessive applications.
Mike Vierstra, a dairy owner in the Twin Falls priority area, said he thinks attention has been paid to the wrong industry. Cows, he said, have been singled out simply because their manure is more noticeable.
"One pivot of spuds puts on more nitrogen than 13,500 cows," he said.
Nate Poppino may be reached at 208-735-3237 or
npoppino@magicvalley.com.
