NHDES Lake Trophic Surveys from 1975 - 2010

This program was initially established in 1975 in order to identify the trophic state of NH
lakes and ponds, as required by Section 314(a) of PL 92-500 (the Federal Water Pollution Control
Act Amendments of 1972). The purpose of the program is to determine lake trophic class and
monitor physical, chemical and biological water quality parameters. Each year, 40 different
lakes and ponds are surveyed, once in the summer and once in the winter. The surveys are
comprehensive physical, chemical and biological surveys, including electronic depth soundings,
macrophyte identifications and abundance ratings, shoreline bacteria sampling and at the deep
spot a temperature/dissolved oxygen/percent saturation profile, Secchi disk transparency
reading, samples for chlorophyll, Ca, Mg Na, and K in the upper water layer, phytoplankton and
zooplankton net hauls for identification and counts and discrete water samples at two or three
depths for pH, acid neutralization capacity, apparent color, conductivity, TP, Total Kjeldahl
nitrogen, nitrite+nitrate nitrogen, chloride, and sulfate. The surveys are designed to assess
current baseline conditions and compliance with water quality criteria, identify the
lake’s trophic status, determine acid rain impacts and the existence of exotic aquatic
plants and provide information for gross long-term trend analyses. See NH_STATION_REPORT for
geographic and lake information