River restoration generally increases river-groundwater interactions, which can become problematic if drinking water is being extracted in the proximity of the river banks, as is the case in the River Thur (7th order stream, north-eastern Switzerland). We hypothesized that local sedimentological conditions could be more significant for faunal interactions than restored vs. channelized conditions. In this study we compared the faunal communities, along with the chemical and fine sediment compositions, of restored reaches with those of channelized reaches having both gravel- and clay-dominated sediments. For this purpose we collected 91 hyporheic water samples from two different depths and three positions within the river channel between June and July 2007. 
The collected data showed extremely low faunal abundances and taxa richness and did not allow a satisfactory comparison of restored reaches vs. channelized reaches due to the high amount of fine sediments in all sampling locations. Local scale entrapment of fine sediments in the interstitial space masked the larger scale gravel vs. clay dominated conditions as well as the effects of river restoration on hyporheic faunal communities. By clogging the interstitial pores, fine sediments reduced faunal abundances and narrowed the range of occurring taxa, excluding all larger interstitial taxa.