All of these lagoons are fully exposed to 'the severe prevailing W to NW waves; whereas, 

 Bolinas Lagoon (with a high-water surface of 4.6 X 10 7 ft 2 ) is well protected by refraction 

 effects from such wave exposure. Since the surface area of the lagoon is a measure of the 

 potential tidal prism, it appears that Bolinas Lagoon inlet would be completely closed if it 

 were subjected to the same wave exposure as the above listed lagoons. 



IV. CONCLUSIONS AND RECOMMENDATIONS 



The Bolinas Bay- Bolinas Lagoon-system is a natural laboratory— unique because perhaps 

 more basic data cover almost every aspect of hydrography, wave action, tidal hydraulics, 

 sediment transport, and the ecosystem than for any other lagoon. There are problems, 

 however, in which further studies are highly desirable to provide knowledge on the natural 

 dynamics of a lagoon system which has been undisturbed by man except for some logging 

 operations in the 1870's. From a consideration of the limited flushing action by tidal 

 currents and the rate of sedimentation in Bolinas Lagoon it appears that the inlet will close 

 completely long before the lagoon fills by sedimentation from the watershed, thus 

 converting the lagoon from a saltwater to a freshwater environment. Those additional 

 studies which are desirable and which would in no way influence the present environment of 

 the Bay-Lagoon system or be unsightly in their operation, but which would be applicable to 

 a better understanding of the natural processes occuring in tidal lagoons in general, follow: 



1 . Install tide gages in the ocean and in the lagoon to obtain data on such tidal hydraulic 

 phenomena as ratio of tidal range in the ocean and lagoon, tidal lag, superelevation, channel 

 friction, and wave setup. 



2. Periodically survey the bottom of the inlet channel to document seasonal changes of 

 the inlet resulting from variations in tide and wave action during the year. 



3. Operate a wave gage offshore from the lagoon inlet to obtain a record of wave height 

 and period. Supplement the wave gage observations with daily estimates of wave direction. 



4. In view of the ecologically depleted condition of parts of the lagoon (pollution, poor 

 circulation, and high sedimentation rates), it appears desirable to investigate further the 

 simple means of correcting this undesirable situation by increasing the tidal prism in the 

 upper reaches of the lagoon. An increase in tidal prism and reduction in sedimentation rates 

 will also delay the time when complete closure of the inlet will occur and convert the lagoon 

 from a salt- to a fresh-water body of water. 



42 



