Evaluation of pool-riffle naturalization structures on habitat complexity and the fish community in an urban Illinois stream

John S. Schwartz, Edwin E. Herricks

Research output: Contribution to journalArticlepeer-review


Urbanization and its associated stressors such as flow alteration, channel modification and poor water quality is a leading cause of ecological degradation to rivers and streams. Driven by public concern to address this issue, there has been a dramatic increase in urban restoration projects since 1990 using in-stream structures. Attempts at restoring the ecological condition of urban streams using structures have produced varied results, but projects do not often meet planned ecological goals. A major challenge to improving the ecological health of urban streams is to better understand how to incorporate ecological assessments into a 'restoration' design framework with reasonable expectations for ecological recovery. A naturalization design framework was used in a project on a 0.62-km reach of the North Branch of the Chicago River in Northbrook, Illinois. Initial surveys of channel morphology, habitat and biota identified poor pool-riffle bed structure and fish biodiversity, which became the basis for research and development of a pool-riffle structure specifically designed for constrained, low-gradient channels. Habitat and fish surveys were conducted pre- and post-construction. The project improved mesohabitat structure, and fish abundance, and biomass and diversity were greater for 2 years following construction (2002-2003) compared to 3 years prior to construction (1999-2001). However, the improved fish metrics were in the low range when compared to rural streams in the same ecoregion, and the fish community consisted primarily of tolerant, slow-water species. Absent were intolerant and riffle dwelling species, such as insectivorous cyprinids and darters. Assessment of pre- and post-project ecological condition and the use of species information provided a basis for ecologically informed design and expanded our understanding of the limitations to restoring urban streams.

Original languageEnglish (US)
Pages (from-to)451-466
Number of pages16
JournalRiver Research and Applications
Issue number4
StatePublished - May 2007


  • Bioassessment
  • Ecohydraulics
  • Fish
  • Habitat instream structures
  • Naturalization
  • Stream restoration
  • Urban streams

ASJC Scopus subject areas

  • Environmental Chemistry
  • Water Science and Technology
  • Environmental Science(all)


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