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Public policy problems are increasingly being characterised as wicked or tame problems, assuming that this classification is also meaningful for attempts to effective problem-solving. But do distinct 'wicked' or 'tame' problems empirically exist? We investigate 37 water-related problems in Germany, based on interview-based data on problem wickedness and official data on policy delivery. Our analysis clearly reveals four clusters of water governance problems (system complexity, uncertainty, tame and wicked problems), based on variations of three factors of wickedness (goals, uncertainty and system complexity). These clusters of problems vary in their effects on different dimensions of policy delivery (goal formulation, stages and degrees of implementation of measures), with significant effects on goal formulation and the number of measures 'in construction'. These empirical insights may contribute to a more systematic design of governance strategies for addressing water governance problems in practice.

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Abstract-To develop a guideline for a simulation test for aerobic degradability in surface water, the fate of [ 14 C]lindane (␥-hexachlorocyclohexane) was studied in laboratory systems using natural river water and sediments. No sterilized controls were set up. Thus, measured data reflect the sum of biotic and abiotic processes. Tests were carried out under various experimental conditions to investigate which of these would affect the feasibility of the test, the fate of lindane, the physicochemical state, and the biological activity within the sediment-water systems. Lindane (37.7 nmol) was applied either to the water (3 L) or the sediment (0.33 L). Sediments remained nonreducing, and there was no serious decline of nutrients nor enzymatic activities. In one experiment up to 14.1% of the applied lindane was mineralized to 14 CO 2 within 50 d and in a second one up to 35.3%. At day 91 of the latter experiment up to 46.8% were found to have been mineralized. Among the experimental factors tested, the method of lindane application and temperature predominantly affected mineralization. The type of aeration and the semicontinuous addition of organic nutrients were of minor importance. Sediments and water collected at the same site but at different times showed variation in carbon content as well as in esterase and dehydrogenase activities. Nevertheless, these parameters could not be correlated with mineralization of lindane during the tests. Between 1 and 9% of the radioactivity volatilized during the tests. At the end, 23 to 66% were bound to sediments and 15 to 45% of the total activity was neither extractable by water nor by cyclohexane.

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