Abstract The innovative technique of Life Cycle Impact Assessment (LCIA) applied to dynamic environmental systems has been recently developed. In this work we investigate a complex system, the Domingo Rubio tideland (Huelva, Spain), where a tidal marsh and a continental lagoon converge. This wetland, catalogued as Natural Park by the Andalusia government, is subjected to a high eutrophicant pressures related to the strawberry culture and the inputs coming from industrial wastes. NO 2 −, NO 3 − and PO 4 3− were analyzed in 41 water samples, obtaining values up to 100 mg L − 1 Σ(NO 2 −, NO 3 −) and 18.5 mg L − 1 PO 4 3−. All these values exceed the accepted levels by the European Environment Agency. N/P ratios and the Aquatic Eutrophication Potentials (AEP) for N and P showed a constant imbalance of the system. During one tidal cycle, the tidal channel can have both N and P as limiting nutrient (P is the limiting nutrient during low tide and N is during high tide) and there exists an alternation of AEP domination too between N and P in the continental area, what points to an excess of both nutrients all over the study area, and to the necessity of diminishing the nutrient inputs and a higher control on these pollution sources as well.