Pond Boss Forums AQUATIC VEGETATION Controlling unwanted plants Blue dye pros and cons

MC - Does the spring enter the pond above or below the waterline? If above the waterline I suggest you collect a water sample and test it for nitrogen and phosphorus. Test in spring right after corn planting or nitrogen application when corn is about 4" to 8" high. Tesing again in summer of fall after a rain storm would also be informative. Presence or absence of nitrogen and phosphorus will give you some indication of what percentage of nutrients are coming from spring water. If nutrients are low in spring water all your nutrients feeding the algae problems are coming from fertilizer runoff - neighbors lawn and farm field. Since you can not control these nutrients or reduce these nutrient sources, I question your ability to ever get this problem fully under control. Water flow through the pond and relatively short water retention times will minimize the affects of any type of chemical treatments. If your spring water tests are fairly "good", I would talk to the local US Soil and Water office about the feasability of, in the future, installing a diversion ditch for the inflowing water. If that is impossible, You have a major problem on your hands if you expect a relatively clean pond. Even if you stocked a high number of grass carp (white amur) they have a high tendency to migrate out with the overflowing water esp during highest water periods. State DNR will not like that.

If it was my pond I would also test spring water once for total coliform bacteria. The presence of coliforms is highly suggestive, but not absolute proof, that the neighbor's septic field leaches into the spring water. Septic leachate not only contains coliform bacteria but also high nutrient levels.