Riparian leaf litter is a major energy source for stream ecosystems, driving carbon and other nutrient cycling and sustaining aquatic food webs. In intermittent streams, cycles of drying and rewetting influence leaf litter accumulation and shredder diversity and abundance. While theory posits that drought can also decrease the quality of riparian leaves entering the stream (e.g., higher C:N ratios, lower leaf phosphorus content, and lower specific leaf area), second-order effects on consumer activity remain largely unexplored. Here, we partitioned the interacting effects of water availability on leaf litter decomposition by (a) shaping invertebrate community composition, (b) affecting leaf litter quality, and (c) controlling stream hydroperiods. We examined: (1) What are the direct (e.g., water presence) and indirect (e.g., leaf litter quality) paths by which hydroperiod alters leaf litter decomposition? (2) How does altered leaf litter quality intersect with flow regime and macroinvertebrate assemblages to influence litter decomposition rates? We hypothesized lower leaf quality and shorter hydroperiods at intermittent sites would lower shredder diversity, density, and litter processing rates. To test these hypotheses, we deployed coarse and fine mesh litter bags (to partition out invertebrate versus microorganism-driven decomposition) across seven sites spanning a hydroperiod gradient in Chalone Creek, Pinnacles National Park, California. Leaf litter from dominant riparian species—Fremont’s cottonwood (Populus fremontii), red willow (Salix laevigata), western sycamore (Platanus racemosa), and coast live oak (Quercus agrifolia)—was monitored over four months. We found the decomposition rates were, on average, 26.7% lower at intermittent compared to perennial sites for each species. Reduced shredder abundances and, for cottonwood and willow, lower litter quality (e.g., specific leaf area) at intermittent sites drove these differences. This research highlights how drought may disrupt river-riparian linkages in previously overlooked ways—not only by reducing litter quantity but also by altering its quality and the invertebrate communities that drive decomposition.