effects of farm runoff?

Answer 1

I have a camp on a beautiful fresh water lake that has a terrible weed problem (now being corrected by chemical treatment). Invasive exotic foreign weeds grow almost without bounds forming surface mats that foul boat propellers and after storms float to shore and putrify if not removed. The lake water is very fertile and has a layer of silt off shore that sustains weed growth. Years ago the sterile outflow from city and town sewer treatment systems was diverted from the lake to reduce nutrients for weed growth. Farms in the 144 square mile drainage basin that feeds water to the lake also cooperated to reduce direct farm runoff to brooks and streams that flow to the lake. Using earthen boundaries to impound and force farm runoff to instead drain into the ground (especially during the spring thaw) reduces nutrients flowing to the lake from manure and fertilizer. By the way the tons of weeds removed from the 4 x 7 mile lake using weed harvesters is sent to farms for use as fertilizer. Cooperation goes both ways and farmers can enjoy the lake too.

Answer 2

Pollutants often found in farm runoff include fertilizer compounds containing nitrogen, phosphorus, potassium, and other nutrients; sediments if tilling has occurred; and pesticides if they have been applied.

These materials can affect streams, lakes, and ponds by causing nutrient enrichment, leading to algal growth and blooms followed by death and decomposition of biomass, causing oxygen depletion with bad effects on fish and aquatic life. Sediments can make water cloudy and reduce penetration of light, reducing algal growth and oxygen supply. And pesticides can be directly toxic to aquatic life.