When you say water louse are you referring to Daphnia?

If so the following information should clear up any doubts you have, as they are a very beneficial to a natural eco-system and a welcomed addition.

Sometimes Daphnia may be used in certain environments to test the effects of toxins on an ecosystem. This makes Daphnia an indicator species, particularly useful in that area because of its short lifespan and reproductive capabilities. Because they are nearly transparent, their internal organs are easy to study in live specimens (an example might be to study the effect of temperature on the heart rate of these ectothermic organisms). They are often fed to tadpoles or small species of amphibians such as the African Dwarf Frog (Hymenochirus biettgeri). Daphnia are also a popular live food in tropical and marine fish keeping.[5]

Sorry Kend but how did this laboratory animal get in the pond?
Water louse is related to wood louse and they are scavengers as they eat detritus normally you would'nt be that aware of them in pond mud, so is there an underlying problem in your pond?

we have lots of these in our pond and they arrived 'naturally', they dont compete for food with tadpoles as they are detrivores, mainly plant bits. about 3 weeks after hatching tadpoles become carnivores. The louse will not affect them.

thanks everyone, they are water louse, the water is very clear, I don't have a pump of any kind,I have just never seen as many .they are covering all the plants in the bottom of the pond, and hundreds of them are sitting on the edge of the pond on the liner. the pond seems to be infested with them. don't know if this is a good or bad sign.I don't have any fish in the pond so they don;t have any predators.

Your natural pond sounds good as the water is clear and perhaps that is why? as water louse feed off dead plants etc. I have fish and I suspect that's why I am not aware of any. lucky you.