Pond Boss Forums AERATION Systems questions Gravel Pit Lake - Aeration ?

Gravel pit lake that is starting to fill, water surface area will be around 14 acres and max depth +25'. BOW is supported purely from groundwater, no other source of water other than from the sky. Probably 8-10 gravel seams, throughout the perimeter, that discharge near the 10 gpm rate. Tested water back in 2024 for dissolved oxygen and measurements came in within the acceptable levels for supporting fish. Water surface elevation usually only fluctuates 4-8" throughout the year most likely controlled by the Colorado River which is a stone throw away. This year a somewhat different story with the drought...

But now moving into stocking the BOW, aeration keeps coming to my mind. Seems like with the groundwater source that the water change-over creates DO levels to be acceptable but with spending $$$ on fish stocking I don't want to come out one day and see all the fish 'belly up'! That'll be a sad day!

Aeration probably doesn't hurt anything, but do I monitor the situation after stocking before thinking more about providing aeration? The question here probably to those pond/lake owners that may have a similar BOW where it's supported by groundwater rather than any other source. Would love to hear your thoughts, experiences, does/don'ts on this particular situation!

All answers have to do with aeration.
Do you live there at the small lake??
Generally - how clear is the water?
Are the shoreline areas slow slope or all steep drop offs as in many quarries?
Do you have a Secchi disk either purchased or homemade?
When you tested the lake back in 2024 what depth/s did you measure the DO?
And what month did you test that water back in 2024?
Does the lake have any rooted plants or string algae growing ?

Yes currently building on the lake property.

The water is clear. Thinking this is due to the groundwater source and no irrigation ditch/creek inflow that brings in sediment. I haven't done a secchi disk test but something I may do this weekend. It'll be a homemade job disk!

When I measured the DO back in late June 2024 I went as far as my arm could reach off of a paddleboard. So around that 2 - 2.5-foot depth. Used those DO kits from CHEMetrics (Indigo Carmine), If I recall correctly DO was at the 9 mg/L level.

Generally speaking the shorelines are sloped but drop off pretty quick, not in a vertical cliff scenario but at 10-12 feet out you're not touching anymore and better know how to swim!

Since dewatering, May 2025, the original area of the gravel pit lake has vegetation growth along bottom. Typical reeds (don't know the type) and other typical weeds that grow here in Colorado. The new portion of lake is free of vegetation because as soon as mining stopped they pulled the dewatering pump and started to fill. New lake bottom in this area is cobbles. Photos attached!



Thanks!

Tentative Comments.
Until the small lake is filled comments are generalizations based on a new water gravel pit lake.

No surface runoff and mostly ground water intrusion the nutrient concentration in the water column should be low with a low nitrogen to phosphorus ratio generally indicating a low density, good quality phytoplankton community. This will feed or produce a good zooplankton community. Both a good basis of the food chain.
Low phytoplankton density and lack of surface water runoff will heavily contribute to clear water conditions. Secchi disk measurements will strongly influence the water depth at where phytoplankton and submerged vegetation will be able to grow and produce dissolved oxygen aka DO.

The initial DO test results of 9 mg/L back in 2024 are normal for early summer for your type of lake. In the future if the lake does not develop low secchi disk measurements around 2 ft or less and large surface algae films do not develop, at this point you should not need artificial aeration in this lake/pond. Get me some Secchi measurements and I will elaborate more on this topic.

Moderately steep shorelines will grow submerged vegetation and Secchi depths will determine how deep these plants will grow on the bottom. You should determine somehow what specific type of plants are now and will be growing in this lake especially the "reeds". Reeds this time of year (Fall) should be producing seed heads that are important in identification of reeds. Get some pictures and we can identify them. Nature will introduce some early invader species of water plants. Some of the first ones will probably be cattails and Chara. Winds and Waterfowl will deposit other seeds from their manure deposits.

Bottom dewatered vegetation growth I think will be primarily terrestrial plants that will when under water, they will die and contribute to the nutrient load in the pond. Accumulated nutrients will mostly determine the overall lake productivity.

It would be good to at least have an alkalinity measurement. Pet shop test kit would give a good idea of the concentration. I would never add lime to a lake/pond this big as it even in with low alkalinity will produce plenty of fish standing crop for most users. Alkalinity and basic nutrient tests will give a good indication of the fish poundage production ability in 13-14 acres.

This is enough until I get more water quality information.

Thanks Bill, appreciate your time and response. I will get some secchi measurements this weekend, including picking up an alkalinity test kit.