The pressure at the bottom of the lake is the weight of the water, minus the weight of the air (i.e. the air pressure at the lake surface), per unit area.

Water weighs 0.0361 pounds/ cubic inch

0.0361lbs/in^3*754ft*12 inches/ft = 326.6 lbs/in^2 (psi)

1 psi = 6895 Pa

326.6 psi = 6895*326.6 Pa = 22.52x10^5 Pa

22.52x10^5 Pa - 1.013x10^5 Pa = 21.5x10^5 Pa