Surface water quality varies widely in the different regions in Thailand. Surface water monitored in the northern, central, and southern regions appear to have poor quality, while water in the eastern region was fair. Compared to other regions, the rivers and lakes monitored in the northeastern region had good quality surface water. In terms of dissolved oxygen (DO), surface water in the northern region ranks the best, approximately 6 mg/L, followed by the northeastern region with DO concentrations of around 4 mg/L. The central, eastern, and central regions rank the lowest, about 2 mg/L. The highest concentration of total coliform bacteria (TCB), among surface waters monitored, was found in the central region with concentrations of TCB higher than 4,000MPN (most probable number)/100mL. In 2003, PCD set up 240 monitoring stations in Thailand's 23 coastal provinces and on significant islands. In 2003, monitoring results showed that coastal water of 68 percent of the stations were in "very good" and "good" quality. Thirty percent of the stations were in "fair" condition and only three percent were in "poor" quality. Compared with past data, coastal water quality was shown to have deteriorated, specifically in the areas into which four main rivers flow. The chief indicators of pollution were DO and TCB. Water quality in the inner Gulf of Thailand, into which the Chao Phraya, Tha Chin, Pak Panang, and Rayong Rivers and several canals discharge, revealed high concentrations of domestic pollutants. Very low DO levels (0.3, 1.8, 3.5 mg/L) were found in the areas of Klong 12 Thanwa, Mae Klong, and Tha Chin. Additionally, TCB and heavy metal levels appeared to be higher than allowable standards in the same areas. In Bang Pakong District the level of total suspended solids (TSS) appeared to be high. The western seaboard generally appeared to have "good" water quality. However, TCB levels in some areas where domestic waste water discharged into the sea without treatment exceeded the standard. Water quality in most areas of the eastern seaboard was in "good" condition, except for high levels of total suspended solids and TCB in the areas of Laem Chabang and Map Ta Phut. Despite rapid growth, overall coastal water quality in the Andaman Sea were still in "very good" condition, except for the few areas that revealed concerns of DO and TCB levels.