DISCUSSION OF RESULTS The Discussion of Results section contains information interpreted for the country as a whole from data collected during the CWSS on four items of special importance to the water supply industry. These are: 1) quality of source water, 2) quality of distributed water, 3) control of health hazards, and 4) influence of water supply system size on operation and performance. Quality of Source Water Surface Water Changes in the quality of a raw water source can result in changes in the quality of treated water furnished to the consumer. Continual deterioration of source quality may force the water utility to use more extensive treatment methods or seek alternate sources to maintain finished water quality. These actions usually result in an increase in the cost of water. In many areas, pollution abatement has not kept pace with the increasing effects of man-made pollution, particularly in our surface waters. As a result, the quality of many water supplies' raw water sources has been threatened. In an effort to evaluate the magnitude of this threat, a portion of the CWSS was designed to obtain information on the past and present source quality for each water supply system studied. Specifically, information was sought during the sanitary survey on the present adequacy of the source with respect to quantity, bacteriological, chemical, and physical quality, and source protection. In addition, an attempt was made to determine if the overall quality of the source had improved, deteriorated, or stayed the same during the past three years. In general, the answers to the latter question were subjective opinions of the water supply system operators. This is a summary of the source quality information obtained from those water systems that have surface raw water sources. For purposes of tabulation, a water supply was considered to have a surface source when: 1. Its only source of raw water was from a river, stream, brook, lake, reservoir, pond, and so forth; or 2. In the case of a combined (surface plus ground) source, more than 50 percent of the annual raw water volume came from the surface source. Supplies for which the relative percentage of surface and ground raw water volumes could not be determined from the CWSS Inventory Form (ECA-18) were not included. Table 12 summarizes the information on source quantity and quality obtained during the sanitary survey. These data show that, in general, the quantity and quality of surface water source was judged adequate by the engineers that surveyed these systems. Only slightly over one-half of the sources, however, were judged to be adequately protected. The sources were used because safe water was provided by adequate treatment. Conclusions on a national basis are heavily influenced by the State of Vermont where many of the unprotected sources did not receive adequate treatment. Based on the operator's opinion, 59 percent reported that the quality of their source had remained the same over the past 3 years. Additional information on this subject was obtained from the National Water Quality Network, initiated by the Division of Water Supply and Pollution Control of the U. S. Public Health Service, in 1957. This network was operated by the PHS until 1966, when the responsibility was transferred to the Pollution Surveillance Branch of the Federal Water Pollution Control Administration (now the Federal Water Quality Administration). Of the 50 original sampling locations established for the network, three are at the raw water intakes for surface water supplies included in this CWSS. These locations are: 1. Ohio River at Cincinnati, Ohio 3. (Kansas City water treatment plant) Mississippi River at New Orleans, Louisiana To obtain additional information about these sources, seven water quality parameters, indicative of the quality of the river for use as a water supply source, were selected. They A review of the data for Cincinnati, Ohio shows that since 1964 there has been: little change in chlorine demand (data limited) 1. 6. 7. a decreasing trend (until 1968) in coliform counts very little change in CCE In general, these data support the opinions obtained during the CWSS that the quality of the Ohio River as a water supply source had either improved or stayed the same in recent years. The data for recent years from the Missouri River at Kansas City show the following: 1. little or no change in chlorine demand, total 2. a marked reduction (approximately 7-fold) in 3. a sharp increase in algal counts up to 1966 4. a decreasing trend in total coliforms The turbidity data, in general, agree with the reductions reported during the CWSS. The coliform data shows a decreasing trend, however, in opposition to the increase in microbiological loading reported in the study. The Mississippi River is the only surface source in the New Orleans SMSA. Most of the water supplies using the river for raw water reported continued deterioration of source quality during the past 3 years. The presence of wastes from a vast complex of upstream sources renders the river difficult to treat for water supply purposes. Tastes and odors are a continual treatment problem in this area. For this sampling station, the following changes in the selected water quality parameters were noted: 1. marked increases in both algal counts and total 2. 3. 4. 5. after an unexplained initial decrease over a period of 2 years, there was a gradual increase in 1-hour chlorine demand a gradual increase in total hardness little change in total alkalinity and CCE generally declining trend in turbidity |