This item about Bolinas Lagoon becoming a salt marsh is ecologically important. As 

 Ritter (1969) points out, Bolinas Lagoon is now a recreation area used for clamming, 

 fishing, boating, nature studies, bird watching, and other saltwater-oriented uses. However, 

 and probably overlooked by those most active in striving to maintain the lagoon in its 

 present natural state, the inlet may close completely long before sedimentation has reduced 

 the lagoon to a salt marsh, the environment will shift in a few years from a saltwater lagoon 

 to a brackish or possibly freshwater lagoon. Examples of closed lagoons in this general area 

 are Abbotts and Rodeo Lagoons. 



To appraise the sedimentation processes at the Bolinas Lagoon inlet requires information 

 such as: repeat bottom and beach face surveys at frequent time intervals, aerial photographs, 

 wave data, littoral-current data, tide and tidal current data, and the physical properties of 

 bottom and beach sediments. A summary of the nature, extent and availability of these 

 various data follows: 



1. Hydrographic surveys by the U.S. Coast and Geodetic Survey (USC&GS) were made 

 in Bolinas Bay as follows: 



Chart No. Date Scale 



H-438 1854 1:10,000 



H-456 1855 1:20,000 



H-721 1858-60 1:100,000 



H-4975 1919 1:20,000 



2. Hydrographic surveys along the northern part of Bolinas Bay near the mouth of 

 Bolinas Lagoon were made by R. M. Towill Corp. for the Bolinas Harbor District at a scale 

 of 1 inch = 200 feet on the following dates (Gilroy, 1970a, App. No. 3): 17 May, 21 Aug., 

 19 Dec. 1968; 15 Apr., and 16 May 1969. 



3. Beach profiles along three ranges on the Stinson spit were surveyed on several 

 occasions by Trask (1959), and Trask and Snow (1961) of the University of California. (See 

 Figure 4.) 



4. Beach profiles along five ranges on the Stinson spit were surveyed by the Corps of 

 Engineers (1965) in March and August 1961. The same well-referenced ranges were 

 resurveyed in March and April 1969 by the California State Lands Division (1970). 



5. A range across the Stinson spit was established by the State Lands Division near the 

 Corps of Engineers' Range BB-3 early in 1969, and was measured daily for about 6 months 

 by Stinson State Park personnel at 16 points along the range. (Thompson, 1970.) 



6. In the vicinity of the range (5) above, the State Lands Division established the 

 position of mean high tide line for a distance of about 500 feet along the beach face on 1 1 

 occasions from October 1948 through December 1969. These data are available from State 

 Lands Division (1970) in Sacramento. 



