Unless you enjoy a chronic problem, I'd tile that part of your watersupply clear around your pond. A wetland is likely going to comsume most of that water during the time of year you need it. The rest of the year, that source will simply bank your nutrient load for your pond to deal with later since metabolic rates of the wetland are low and flow rates are likely high. It is always advisable to run an chemical profile before any decision. It's cheap medicine.

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