Effects of Grade Control Structures on Fish Passage, Biological Assemblages and Hydraulic Environments in Western Iowa Streams: A Multidisciplinary Review

Abstract

Land use changes and channelization of streams in the deep loess region of western Iowa have led to stream channel incision, altered flow regimes, increased sediment inputs, decreased habitat diversity and reduced lateral connectivity of streams and floodplains. Grade control structures (GCSs) are built in streams to prevent further erosion, protect infrastructure and reduce sediment loads. However, GCS can have a detrimental impact on fisheries and biological communities. We review three complementary biological and hydraulic studies on the effects of GCS in these streams. GCS with steep (≥1:4 rise : run) downstream slopes severely limited fish passage, but GCS with gentle slopes (≤1:15) allowed greater passage. Fish assemblages were dominated by species tolerant of degradation, and Index of Biotic Integrity (IBI) scores were indicative of fair or poor biotic integrity. More than 50% of fish species had truncated distributions. After modification of GCS to reduce slopes and permit increased passage, IBI scores increased and several species were detected further upstream than before modification. Total macroinvertebrate density, biomass and taxonomic diversity and abundance of ecologically sensitive taxa were greater at GCS than in reaches immediately upstream, downstream or ≥1 km from GCS. A hydraulic study confirmed results from fish passage studies; minimum depths and maximum current velocities at GCS with gentle slopes (≤1:15) were more likely to meet minimum criteria for catfish passage than GCS with steeper slopes. Multidisciplinary approaches such as ours will increase understanding of GCS-associated factors influencing fish passage, biological assemblage structure and other ecological relationships in streams. RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. ABSTRACTLand use changes and channelization of streams in the deep loess region of western Iowa have led to stream channel incision, altered flow regimes, increased sediment inputs, decreased habitat diversity and reduced lateral connectivity of streams and floodplains. Grade control structures (GCSs) are built in streams to prevent further erosion, protect infrastructure and reduce sediment loads. However, GCS can have a detrimental impact on fisheries and biological communities. We review three complementary biological and hydraulic studies on the effects of GCS in these streams. GCS with steep (≥1:4 rise : run) downstream slopes severely limited fish passage, but GCS with gentle slopes (≤1:15) allowed greater passage. Fish assemblages were dominated by species tolerant of degradation, and Index of Biotic Integrity (IBI) scores were indicative of fair or poor biotic integrity. More than 50% of fish species had truncated distributions. After modification of GCS to reduce slopes and permit increased passage, IBI scores increased and several species were detected further upstream than before modification. Total macro...

Fish Assemblage Relationships With Physical Characteristics and Presence of Dams in Three Eastern Iowa Rivers

“…Numerous studies have documented negative effects of dams on fish in Midwestern rivers. Blockage of fish passage by dams and similar structures has been demonstrated in several studies (Pellett et al ., ; Santucci et al ., ; Butler and Wahl, ; Thomas et al ., ), with some illustrating how fragmentation of rivers resulted in truncated distributions and degraded fish assemblages (Santucci et al ., ; IDNR, ; Gelwicks and Steuck, ; Thomas et al ., ; Wang et al ., ). In a review of conservation status of catastomids, Cooke et al .…”

“…The abundance of dams nationally (Graf, ) and the large literature documenting negative effects on fish passage and fish assemblages (Rinne et al ., ) suggest that these impacts are widespread. The large number of dams and other man‐made structures impeding fish passage in Iowa rivers and streams (IDNR, ; IWC, ; Thomas et al ., ) suggest that these impacts are probably also common in Iowa.…”

“…Fragmentation by dams and the resulting blockage of upstream–downstream movements can also have significant impacts on river fish assemblages (Dynesius and Nilsson, ; Pringle et al ., ; Rinne et al ., ). Numerous studies in Midwestern rivers have documented blockage of fish passage and fish assemblage degradation associated with dams and grade control structures (Santucci et al ., ; IDNR, ; Butler and Wahl, ; Thomas et al ., ; Wang et al ., ). The abundance of dams nationally (Graf, ) and the large literature documenting negative effects on fish passage and fish assemblages (Rinne et al ., ) suggest that these impacts are widespread.…”

Lampreys: Biology, Conservation and Control

“…Projects that cause physical disturbance to the substrate include dredging (e.g., for channel maintenance and mining), road-crossing modifications (e.g., culvert replacements), and instream structures for grade control (Streif 2009;King et al 2011;Thomas et al 2013). 3), special attention must be paid to these areas in any consideration of the impact of development proposals on lamprey conservation.…”

Bed Morphology around Various Solid and Flexible Grade Control Structures in an Unstable Gravel-Bed River

“…Both natural processes such as landslide damming [1,2] and anthropogenic causes such as dam construction [3,4], bed mining [5], land-use changes [6,7] and channelization [8] could destroy the relatively steady equilibrium states of rivers. In particular, gravel-bed rivers that flow from large-gradient mountain regions to low-gradient plains regions would become extremely unstable [9,10].…”