My sister has a pump and dump heat pump for her swimming pool in Flordia. She takes water from the lake. Problem is that she has to back flush, run acid through her heat pump and clean the screen on the water intake from lake. Algie and crap from lake will build up in the heat pump.
A good HVAC guy should be able to tell you the water flow rate which will depend on the size of heat pump.
I would pump from a clean well. In the summer, A/C, use the water for watering the lawn, animals or garden. In the winter, I would dump it in a lake.
I have heard of people running pipe in their lake. Well water is around 55, in the winter the water temp at the bottom of a lake, when there is ice on top of lake, is around 36-37(?) A heat pump won't work well at those lower temps.
What you are trying to do has been done. Talk to a HVAC guy and get his opinion.