The relative importance of autochthonous versus allochthonous resources to stream food webs varies across time and space. Canopy composition and cover, benthic substrate composition, and organic matter retention all mediate resource availability. We hypothesized that the relative importance of allochthonous versus autochthonous resources available to macroinvertebrates would increase following a 100-m experimental stream restoration designed to increase organic matter retention by adding 25 large logs. Natural abundances of δC¹³ were measured seasonally for the most productive macroinvertebrates one year before and one year after log addition in a control and treatment reach using a BACI design. We observed localized increases in organic matter retention associated with added logs, but no significant reach-scale increases. δC¹³ values shifted towards allochthonous signatures in several taxa, including representatives from all functional feeding groups. Using δC¹³ values in a multi-source mixing model, we found that the carbon fueling macroinvertebrate biomass shifted from ~37% allochthonous before wood addition to ~58% after wood addition. Modest and localized changes in organic matter retention appear to have altered the transfer of carbon through the macroinvertebrate food web. We intend to probe our results further by combining isotopic values with macroinvertebrate secondary production measurements.