Federal land-holdings can provide large blocks of contiguous habitat, but in many cases, aquatic organisms depend on movement within and among these blocks to complete their lifecycles and sustain populations. The area under management by the USDA Forest Service provides 18% of the nation's fresh water, including more than half of the water in the western US. The agency's mandate to support multiple uses requires many miles of roads to provide access for timber harvest, oil and gas exploration, and recreation. The National Forests and Grasslands in Texas (NFGT) encompass 273,493 ha (675,815 ac), with 6547 km (4068 mi) of roads intersecting over 644 km (400 mi) of streams. A 2007 survey of 7 national forests in the southern US indicated that less than 50% of these crossings provided passage for most species of fish. Similar results were evident in our 2006 and 2007 assessments of NFGT streams, which indicated that 50% and 52% respectively, were impassable. In subsequent years, we attempted to improve fish passage on the NFGT. In 2014, we employed the same sampling protocol at 57 crossings, 40% of which were impassable, and another 19% were indeterminate—not assuring passage in all situations. The need for scheduled culvert maintenance presents both challenges and opportunities for improving fish passage. Following a record drought in 2011, the challenge for strategically planned passage-improvement projects was greater than ever. Most NFGT streams stopped flowing in 2011 and subsequent dry years, making fish passage critical to recolonization of headwater streams, averting the loss of fragile range-fringe populations, and limiting opportunities for stronger swimming, native cyprinid invaders to expand and displace endemics.
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Vol. 15 • No. sp9