STATEWIDE BALANCE, 1970 



The general chloride distribution for 1968-1970 in New Hampshire is given in 

 Figure 2. These data are taken where possible from municipal water supphes 

 utilizing ground water. However, private well supplies and in a few cases 

 municipal ponds or lakes are used to fill in the gaps. Except for municipal 

 supplies an attempt was made to avoid wells contaminated with road deicing 

 salt. The intent is to show the overall picture without emphasizing local 

 problems such as weUs close to highways. Some of the values near the coast may 

 reflect saline-water intrusion. 



The approximate chloride balance for 1970 is given in Table 3. Here the 

 general steady-state assumption is not so bad for water, but problems do occur 

 for chloride. For example, a large Water body such as Lake Winnipesaukee or 

 groundwater in an extensive glacial deposit may have a residence time of a 

 number of years. Therefore, chloride content to some extent is a function of 

 what happened in prior years. 



Put another way, if road deicing salt is either increased or decreased one year 

 the resulting effect will not necessarily occur entirely in the same year or even 

 the next year. 



In 1971, 103,000 tons of chloride (equivalent to 169,000 tons of sodium 

 chloride) were shipped into New Hampshire.^^ Similar data are not available for 

 1970. This compares favorably with the 118,000 tons calculated for 1970 for 

 human activities and road deicing salt in Table 3. 



CHANGES FROM 1920 to 1970 



A comparison of Figures 1 and 2, Tables 1 and 3, or the 1920 and 1970 

 chloride columns in Table 2 gives a general picture of what happened from a 

 period of reduced human activity to recent times. The increases in chloride 

 concentrations may not seem large, but they do represent substantial increases in 

 storage. An even clearer picture is given in Figures 3 through 9 which are scatter 

 diagrams of chloride plotted against time for seven municipal water supplies. The 

 locations are shown on Figure 2. These examples were selected to cover the state 

 geographically. They are from ground-water supplies except Laconia which 

 represents outflow from Lake Winnipesaukee. 



Chloride is plotted for convenience on a logarithmic scale on Figures 3 

 through 9, but there is no necessary implication that chloride is actually 

 increasing logarithmically over extended periods of time. Therefore, any attempt 

 at projections beyond final data points in 1970 should be done with extreme 

 caution. Also, the data points are from all samples sent into the State laboratory, 

 and it is not possible to follow any one source except Laconia with time. Some 



^^I U.S. BUREAU OF MINES, MINERAL YEARBOOK, 1971, METALS, MINERALS, 

 AND FUELS 1031-1041 (1973). 



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