Drainage‐conditions as we find them today, in the San Joaquin Valley, are largely man‐made. Without attempting to go into detail, or, in fact, even to verify this statement from historical records, it would appear logical to believe that the only primeval need for drainage in the Valley was confined to its flatter portions which were overflowed during the spring and early summer. Our characteristic two‐season climate would limit overflow to periods of heavy rains from January to March and to the first few hot days of early summer when the accumulated snows were melting rapidly. Probably the only permanently swampy areas were the Delta country at the confluence of the San Joaquin and Sacramento rivers where the influence of tidal action was more dominant than the flood‐stage of the streams and the Tulare and Buena Vista Lake areas of Kings and Kern counties. Overflowed areas along the San Joaquin from Mendota to the delta I have not considered as permanently wet as they probably dried up completely during the late summer a