Rockport keeps an eye on phosphate levels in its ponds

Thu, 08/16/2018 - 7:45pm

    The Rockport Conservation Committee has partnered with the Volunteer Lake Monitoring Program to collect more information about the health, ecology, and function of five ponds in Rockport. On June 16, volunteers for Chickawaukie Pond, Rocky Pond, Lily Pond, Tolman Pond, and Maces Pond traveled to Auburn to be trained and certified in how to monitor Secchi disk transparency, as well as how to properly take phosphorous samples. 

    Volunteers working with the VLMP recently completed initial Total Phosphorus surface grab sampling on their designated ponds. Chickawaukie Pond, Rocky Pond, Lily Pond, Tolman Pond, and Maces Pond were all sampled between July 17-20. The VLMP provided a pre-measured vile to retrieve the surface grab and an Erlenmeyer flask for the sample to be stored in.  

    The samples were then transported to the Maine Health and Environmental Testing Laboratory in Augusta where the surface grab samples were analyzed on July 25. Tolman Pond, Maces Pond, and Rocky Pond all had Total Phosphorus levels of 14 micrograms per liter (ug/L), Lily Pond had a TP level of 13 ug/L, and Chickawaukie Pond was 12 ug/L. The Maine state average for Total Phosphorus is 12 ug/L, and it is recommended that TP levels remain below 20 ug/L. 

    Total Phosphorus tests measure all forms of phosphorus in a sample, including orthophosphate, condensed phosphate, and organic phosphate. Orthophosphates are the main components in agricultural and residential fertilizers and is most readily used by plant and animal life.

    Condensed phosphates are inorganic phosphate compounds that contain salts and/or metals, and are used in industry and as food additives. Organic phosphates are formed through biological processes and are released via human waste and food residue.

    Phosphorus enters water bodies predominantly through stormwater runoff and promotes the eutrophication (nutrient enrichment) of lakes and ponds. The increased nutrient levels in water bodies, combined with other environmental influences such as sunlight and temperature can trigger algae blooms which, over time, can alter dissolved oxygen levels, decrease water clarity, and alter ecosystem dynamics. 

    The good news is that ponds tested in Rockport were, on average, only 1.4 ug/L above the Maine state average of 12 ug/L for Total Phosphorus, and were 6.6 ug/L below the recommended level of 20 ug/L.

    Volunteers for the VLMP plan to do a second Total Phosphorus surface grab sample and test in mid-August while continuing to take Secchi Disk Transparency readings twice a month.