WASHINGTON, Feb. 6, 2015 — The Agriculture Department could put critical wildlife habitat at risk across the upper Midwest by changing the way it maps wetlands in four states, according to conservation groups and an association of state wildlife agencies.

Under a proposal by USDA’s Natural Resources Conservation Service (NRCS), its state offices in Iowa, Minnesota, North Dakota and South Dakota will start making wetland determinations on farmers’ land based primarily using aerial photography, rather than on-site visits.

Twenty-two organizations, including the Association of Fish and Wildlife Agencies, the National Wildlife Federation and state offices of The Nature Conservancy, say in a letter to the agency that by relying on aerial imagery NRCS workers in state offices could miss temporary wetlands in the Prairie Pothole region.

NRCS state offices follow what is called State Off-Site Methods (SOSM) for identifying wetlands and determining conservation compliance, which bars farmers enrolled in commodity and crop insurance programs from destroying wetlands to grow crops.

NRCS officials say the new process will be faster, less expensive, more accurate and, for the first time, consistent across all four states.

But the wildlife organizations aren’t convinced. “First, we want to ensure that the proposed SOSM produce wetland determinations that are at least as accurate as the previous state wetland mapping conventions,” the groups wrote. “Second, we want to ensure that the SOSM are not systematically biased against the seasonal and temporary wetlands that are so important and so prevalent in the PPR (Prairie Pothole Region).”

The letter said NRCS should guarantee the proposed changes won’t compromise the accuracy of wetland determinations by conducting a comparative analysis between offsite and onsite determinations.

It also suggested NRCS develop a public online database of wetland hydrology and allow the U.S. Fish and Wildlife Service to independently verify the adequacy of the new method. In addition, NRCS should collect spring imagery data, as opposed to late summer aerial photography, as reference for future use, the groups say.

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According to NRCS officials, wetland determinations in the Prairie Pothole Region often are already made off-site using imagery and other data sources obtained during what are considered normal climatic conditions.

“In South Dakota, the wettest part of the growing season is in early May, but we can’t be on everyone’s farms in early May, so we use other indicators (of wetlands) because farmers do not want to wait, and we have found high correlations between these indicators and on-site conditions,” said Jerry Jasmer, the NRCS state resource conservationist in the state.

While this imagery is required to clearly show the presence or absence of wetlands and their boundaries in normal years, the wildlife advocates argued it does not adequately represent “the precipitation conditions that influence a wetland’s hydrology” in a given year.

NRCS officials said they may use laser-based remote-sensing data called LIDAR in all four states and also have 30 years of annual cropland photos. “We have techniques to assess whether those photos were taken in appropriate conditions,” said Paul Flynn, the NRCS state resource conservationist in Minnesota.

“We were inconsistent in the past because we weren’t looking at the same base number of years… (but) we’ve consolidated the four states’ processes into one process, one reference, with the same aerial images looking for wetness signatures,” Flynn said.