DISAPPEARED BLIND VALLEYS ON DIGITAL USGS 7.5 MAPS

Three karst blind valleys accurately shown on the 1960s paper 7.5 minute Cherry Grove and Wykoff, MN USGS topo maps, are not shown on 4 recent on-line, digital versions of those the topo maps. The closed contour blind valleys were "disappeared" from the digital versions by adding (non-existent) linear channels connecting the previously closed contour lines to down valley surface drainages, -- thereby removing the closed contours. The streams previously shown as sinking in the blind valleys are drawn as flowing through the blind valleys and continuing on the surface. Decades of field observations, multiple dye traces and now confirmed by recent LiDAR mapping unambiguously show that the closed contour blind valleys and sinking streams exist -- and existed when the digital topo maps were prepared and published.

For example, the upper Canfield Creek sinks in the York Blind Valley in sec 21 of York Twp (on the Cherry Grove topo map). Repeated dye traces show that the sinking water resurges in Odessa Spring about 11 miles ESE of the Blind Valley on the Upper Iowa River. The York Blind Valley not only pirates the runoff from several square miles of the nominal Root River basin to the Upper Iowa River basin, but the York Blind Valley creates an interstate water transfer.

The map changes were not accidents and were not based on updated information. The changes were consciously made to the digital USGS maps. By whom and why? Have analogous changes been made to the USGS topo maps in other karst areas of the United States?

A real potential environmental management problem exists here. New Environmental management decisions based on the "most recent available" maps and information may be unaware of the major karst features correctly shown on the 1960s maps. Such management decisions could have major, negative, unanticipated results.