Analytical approaches that use empirically-derived environmental optima to infer ecological conditions are commonly used in ecology.  Similarly, analytical approaches that consider the functional characteristics of biota, such as life-history and habitat preference, are receiving renewed attention in community ecology.  Species traits are often used to describe these characteristics because they link functional roles of biota with environmental factors.  In contrast to the empirical estimates of optima, trait characterizations are often assigned based on best professional judgment.  We use information for benthic invertebrate assemblages in streams to consider whether trait characterizations correspond with empirically-estimated optimum values.  Trait characterizations were summarized from a compiled database of benthic invertebrate traits for North America.  Optimum values were estimated from invertebrate assemblage and environmental data from the Western United Sates.  For temperature, traits and optima agree, where optima are low (12 C) for cold-water biota and significantly higher (27 C) for warm-water biota.  Many sediment optima agree with traits.  However, in some cases trait descriptions and sediment optima do not match, e.g., some gastropods and ephemeroptera.  In these situations we may be able to refine trait descriptions with empirical information.  Here we explore the opportunities for updating the traits database using empirical estimates of optima.