IR,

IMHO, place the pump very near the lake. Centrifugal pumps are meant to push not pull. Pumps have a limited suction side usually 10 feet elevation maximum. What is your pumps lift capacity head and your expected flow rate for that head? What is the pump's type and brand? Aloha

My pump is a new Gould "Irrigator" centrifugal pump rated 1 HP. Lift is 25 feet of head, 30 PSI discharge pressure and suction lift in feet is 41.

No idea what "suction lift in feet" actually means!!!

I am most likely going to locate the pump close the lake, about 5 feet above normal pool level to allow for flooding.

IR,

Seems to me you are depending on the suction lift being 41 ft so that you can reach the top of your 33 vertical feet of elevation to the lawn & Garden. 41 feet of suction is unrealistic. Here is what I would do since you already have the pump. Trial and error is always a good thing. Try your pump at different locations up the slope. Find your optimum point where suction is manageable and not too excessive and pressure to the system the greatest. Gonna have to buy the pipe and fittings anyway just don't make it permanent until you find that ideal pump location. I would start with 10 feet of vertical elevation from the lake and go higher by 5 foot increments. Also use a larger diameter pipe to decrease the friction loss from the long pipe length. JMHO Aloha