
The Grande Ronde Valley is defined by a complex network of natural waterways and early irrigation infrastructure in this late twentieth-century study of Union County. The landscape is dominated by the meandering course of the Grande Ronde River and its interaction with the State Ditch, a significant hydraulic feature that straightened the river's flow through this fertile agricultural basin. Small settlements like Conley and Wright are positioned along a grid of rural roads, including Sandridge Road and Booth Lane, reflecting the region's enduring farming character. To the south, the Ladd Marsh Game Management Area preserves a substantial wetland environment around Ladd Marsh, where Ladd Creek and the Ladd Creek Pickup Ditch converge. This map captures the intersection of managed wildlife habitats and the aviation needs of the valley at the La Grande-Union County Airport.
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This is the sole edition of this map. No revisions or reprints were ever made.
1906 · Telocaset
USGS Topo · 1:125,000
1953 · Pendleton
USGS Topo · 1:250,000
1955 · Grangeville
USGS Topo · 1:250,000
1956 · Pendleton
USGS Topo · 1:250,000
1959 · Grangeville
USGS Topo · 1:250,000
1963 · La Grande SE
USGS Topo · 1:24,000
1963 · Summerville
USGS Topo · 1:24,000
1965 · Conley
USGS Topo · 1:24,000
1965 · Glass Hill
USGS Topo · 1:24,000
1965 · Union
USGS Topo · 1:24,000