Abstract The stream restoration potential of recreational modifications made to lowhead dams on an urban reach of Buck Creek, in Springfield, Ohio, is dependent on constraints imposed by the urban infrastructure on stream grade. A privately led initiative to improve the recreational potential of a 9 km reach of Buck Creek and its tributary Beaver Creek includes the modification of four lowhead dams. The hydraulic heights of these dams will be replaced with a series of v-shaped drop structures engineered to create hydraulics conducive to kayak play. The drop structure is a constructed channel constriction composed of a hard step in the long stream profile immediately upstream of a scour pool, forming a morphologic sequence of constriction, step, and pool. In this study, we assess the potential benefits of these changes for urban stream restoration. Two of the dams have been modified to date. Stream quality, as measured by the qualitative habitat evaluation index (QHEI), dissolved oxygen of surface and substrate water, and the pollution tolerance index (PTI), increased at the Snyder Park site but decreased at the Art Museum site. Stream quality increased at the Snyder Park site, where stream grade could be lowered upstream of the lowhead dam, but decreased at the Art Museum site, where grade upstream of the lowhead dam had to be maintained because of water and wastewater utilities buried in the channel bed. Where stream grade is lowered in the former impoundment, sand and gravel deposits upstream of the constriction are not embedded with finer particles and organic matter. Increased QHEI values, particularly the substrate metric, and greater abundance and diversity of pollution-intolerant macroinvertebrates, supported by higher dissolved oxygen in the substrate water, characterize the Snyder Park site. At the Art Museum site, the v-shaped constriction increased the upstream impounded area. The substrate has become embedded with fine sands, silts, and organics, lowering QHEI values, dissolved oxygen is critically low in the substrate, and macroinvertebrate populations are more pollution-tolerant. The results highlight the significance of stream grade if stream restoration is to be incorporated into the engineering design of in-stream recreational features.

Abstract The objective of this field trip is to examine variability in stream systems in west-central Ohio at different time and space scales. Scales of study range from watershed changes over 10 3 –10 4 years as drainage networks are established during glacial retreat, to reach-scale changes in tributary streams in response to human impacts and land use change over 10 1 –10 2 years, to diurnal and event-driven changes in water quality over 10 –2 to 10 –3 years. Drainage network changes in the Little Miami River and Mad River systems occurred through stream capture and were dependent on the location of early meltwater channels relative to ice lobe position and relict bedrock topography. At the reach scale, channel morphology (width, depth, slope, shape, and pattern) is dependent on mean discharge of water and sediment to the reach. Tributary streams to the Little Miami River, Mad River, and Buck Creek illustrate the impact that historic changes in land use, water and sediment discharge, channelization, and straightening of stream reaches have had on channel morphology and vertical stability. At the cross-section scale, flow characteristics, including stream stage and physical water quality parameters (temperature, pH, specific conductivity, oxidation-reduction potential, dissolved oxygen, and turbidity), are being measured on Buck Creek and Beaver Creek. Though some characteristics change diurnally in response to internal stream processes, event-based changes in response to stormflow reflect source area contributions of runoff and sediment.