Forests are integral to sustaining clean water resources and healthy watersheds. It is critical, therefore, that managers fully understand the potential impacts of their actions on myriad ecosystem services provided by forested watersheds. While forest hydrologists have long used paired-watershed experiments to elucidate the complex interactions between forest management and watershed biogeochemical and ecohydrological processes, there is still much to learn from these studies. Here, we present an overview of the process for designing a paired-watershed study using a large harvesting experiment at the Caspar Creek Experimental Watersheds in coastal California as an example. We detail many considerations when designing such an experiment and highlight the wide range of scientific investigations that are part of the larger experiment. Paired watershed studies are a great example of community engaged scholarship and offer the unique opportunity to work with land managers to solve applied problems while simultaneously discovering new fundamental knowledge about how watersheds function.

The ranges and abundances of species that depend on freshwater habitats are declining worldwide. Efforts to counteract those trends are often hampered by a lack of information about species distribution and conservation status and are often strongly biased toward a few well-studied groups. We identified the 3,906 vascular plants, macroinvertebrates, and vertebrates native to California, USA, that depend on fresh water for at least one stage of their life history. We evaluated the conservation status for these taxa using existing government and non-governmental organization assessments (e.g., endangered species act, NatureServe), created a spatial database of locality observations or distribution information from ~400 data sources, and mapped patterns of richness, endemism, and vulnerability. Although nearly half of all taxa with conservation status (n = 1,939) are vulnerable to extinction, only 114 (6%) of those vulnerable taxa have a legal mandate for protection in the form of formal inclusion on a state or federal endangered species list. Endemic taxa are at greater risk than non-endemics, with 90% of the 927 endemic taxa vulnerable to extinction. Records with spatial data were available for a total of 2,276 species (61%). The patterns of species richness differ depending on the taxonomic group analyzed, but are similar across taxonomic level. No particular taxonomic group represents an umbrella for all species, but hotspots of high richness for listed species cover 40% of the hotspots for all other species and 58% of the hotspots for vulnerable freshwater species. By mapping freshwater species hotspots we show locations that represent the top priority for conservation action in the state. This study identifies opportunities to fill gaps in the evaluation of conservation status for freshwater taxa in California, to address the lack of occurrence information for nearly 40% of freshwater taxa and nearly 40% of watersheds in the state, and to implement adequate protections for freshwater taxa where they are currently lacking.