“…For all dimictic lakes but one, diversion of external P loading was established concomitantly, implying that the improved water quality cannot be ascribed solely to the Al treatment; however, a two-thirds decrease in hypolimnetic TP build-up in five of the lakes points to reduced internal P loading as a major cause for improvement. For the shallow lakes, three treatments were unsuccessful and the authors suggest that extensive growth and subsequent decay of macrophytes may have mobilized P buried deeper in the sediment and thereby created a bypass of the Al-treated sediment layer (Welch & Cooke, 1999;Cooke et al, 2005). More information from both published and unpublished cases has later been gathered by Welch (Welch, 2005, Welch, E., personal communication) and an evaluation of the short-term success, mostly conducted by lake managers, reveals that treatments were successful in 56 of 75 lakes and unsuccessful in 19.…”