1. Research linking river ecology and hydromorphology is driven by concerns about hydromorphological pressures (e.g. abstraction, land-use change) and legislative (e.g. EU Water Framework Directive) or management needs (e.g. climate-change adaptation). Unfortunately, much of the science is still weak or qualitative (cf. links between ecology and water quality). 2. Rapid progress is required, but financial resources are limited. In response, research opportunities using existing ecological and hydromorphological data and survey methods need to be explored further. 3. There are challenges inherent in using existing data, which are often collected for different purposes, and this paper highlights aspects of spatial scale, temporal coverage, sampling biases, data quality and mining, and the problems faced when using pre-defined sets of variables. 4. While the prospects for exploiting existing data are mixed, distinct strengths arise from extensive geographic coverage, the ability to improve the evidence base rapidly and at low cost, and the generation of testable hypotheses. 5. Current survey methods usually record biological or hydromorphic patterns, or inventories of features (cf. physical processes, or ecosystem functions or services). Their greatest use is likely to be in extending current spatially extensive biological or water chemistry monitoring to more integrated ‘eco-hydromorphic’ monitoring. 6. With further methodological development, there is real scope for illuminating several aspects of riverine ecology, including the direct ecological and physical consequences of modifying river systems; revealing indirect sensitivity to other pressures, such as climate change; offering a more holistic picture of the distribution of pressures on river ecosystems; and developing hydromorphology as a unifying theme in river studies. However, such developments require funding commitments from research sponsors. Copyright © 2010 John Wiley & Sons, Ltd.