Pressure measurements made in various turbid natural waters have led to the inference that the effective depth-mean in-situ density values peff of these waters are less than (approx equal to 2.70%) their static bulk densities and also (approx equal to 0.4% - 4.5%) that of the density of the same water without suspended sediment. Teh values of peff in a given site differed from one tidal cycle to another (approx equal to 1.9%). These values varied slightly (less than 0.8%) from mid-tide to slack water of the same tidal cycle, with peff being lower at mid-tide. It was found that the use of bulk deisity to estimate tidal height gave an under-estimation of tidal range (upto 7%). The under-estimation has been corrected (to within plus or minus 1.5%) with the use of peff parameter. For clear waters there was no observable under-estimation in tidal range. The observations strongly suggest that suspended sediments play a hitherto unknown role in the apparent in-situ density reduction effect seen in turbid natural waters.