Gravel Pit Pond (lake?) Advice

Hello everyone. I feel like I have one opportunity to do things right so I come to the experts for advice.

We have a gravel pit that is still being mined, and we are working on the next (and potential final) contract. Any restoration desires need to be laid out up front in this contract.

Goals: I want a private healthy lake for swimming and fishing. The kids and I swam out there on Memorial Day and it was glorious.

Current State: There are 15 acres of water. 25 feet at the deepest. Average depth maybe around 15 feet. There are 3-4 ponds that should all be made into one when everything is done. Below is some amateur drone footage from last fall. I added 50 lbs of shiners to the middle pond last November. I am not sure if they lived as I did very little to create any habitat for them. The pond seems relatively sterile.... The blue color of the water is interesting to me--is that phytoplankton?

DRONE FOOTAGE LAST FALL

Questions: What can/should I do now? What do we need to make sure to get out of the mining company? Are there any links to previous threads about such a topic? (I looked but did not find much) WHat kind of water tests should I do before I add more fish? Is it too early in the life of the ponds to add fish? Will future mining harm fish? (mining is nothing more than them pulling gravel out with a backhoe)

I feel like I could go on and on... Can anyone help me?

The first step is to check water quality. Some pits can have really low pH depending on what was being mined.

Check water quality for

pH--Several times per day and 1 hour before sunrise and 1 hour after
alkalinity
water hardness
Dissolved O2-Find out if you are developing a thermocline and how deep.

Thank you! Do these values change much in different spots? Or can I measure these values in the same spot?

Is there an economical way to measure dissolved oxygen?

My aquarium test kit should work for the rest of the tests. Thank you! I shall come back with results.

Send water samples to Texas A&M for testing. If it were my kids, I would want to do the heavy metals testing option in addition to the routine tests.

http://soiltesting.tamu.edu/files/waterweb1.pdf

pH will vary according to water depth and presence of aquatic vegetation.

What is your agreement like with the mining company? If it were me, I'd milk it for everything you can - you want a swimming beach? Have them make one with their earth moving equipment. You want all 3 ponds connected? Draw out a plan for connecting them and have them make it happen. I would have them provide bathymetry data - they dug the holes, they should provide the data. The bathymetry will help you choose locations to add cover, narrow down spawning habitat, and so on

Do you have any vegetation? Curly leaf pond weed? American pond weed? cabbage? etc? Any other fish present other than the shiners?

Locally there are some former sand/gravel pits that were donated to the county for public use a few years back.
https://muscatinecountyconservation.com/mccb-areas/deep-lakes-park/