Empirical evaluation of the conceptual model underpinning a regional aquatic long-term monitoring program using causal modelling

•Causal hypotheses identified in conceptual model used for interim evaluation.•Bayesian path analysis used to estimate cumulative, direct, and indirect effects.•Surrogate variables for management intensity were used and insufficient for models.•Biological condition was related to fine sediment and instream temperature.•Survey design for status and trends insufficient for prescribing management changes