Phosphorus is one of the three key nutrients that plants require in the largest quantities and is commonly found in many, if not the majority, of commercial fertilizer products. Unfortunately, it is the principle cause of declining water quality in Connecticut’s lakes and ponds. Where does the phosphorus come from? – mostly failing septic systems and fertilizers! Last May, legislation was passed that would limit the use of phosphorus
on established lawns. Fertilizers containing phosphorus can still be used when seeding, overseeding and laying down new sod. On established lawns, a phosphorus-free fertilizer should be used for routine maintenance fertilizer applications unless a soil test (taken within the past 2 years) indicates a need for phosphorus.

More information see:

http://www.soiltest.uconn.edu/documents/PhosphorusLegislationinConnecticut.pdf