Dam Water

[CM4Me]

About March '09 we had an excavator dig a crescent shaped dam for us, on gently sloping land, roughly 36m x 20m (at the widest points) with a small island in the middle.

Primarily, the source of water is subterranean, with some surface run-off during heavy rains. When full it has a maximum depth of about 2.5m.

The soil, in & around, ranges predominantly from 'crumbly clay' to patches of 'sticky clay'.

The colour of the water now (April '10) is about the same colour as a eucalyptus tree old leaf (i.e. a soft grey/green). Visibility is about 0.5m.

There are 6 or so clumps of lotus plants growing, (the common one with deep reddish leaves & pink flowers).

During the last wet season we had lots of frogs. I have also frequently observed small fish jumping for insects. I am also told there are shrimps in the dam as well. How they (the fish & the shrimps) arrived is a mystery to me as we certainly haven't put them there (but intend to stock Pla Nin & Tab Tim after the house is built, whenever). I have also noticed birds (swallows I think) frequently skimming / drinking the water.

There is also the occasional large water snail, the ones that lay clusters of pink eggs (which I'm constantly on the lookout for & destroy).

Since the dam was dug we have also planted many young fruit trees. With the current hot dry season in full swing we need to water these young trees with water from this dam. I estimate we are using about 4,000l/week.

So far this summer (the 1^st) the level of water in the dam has dropped by approximately 0.5m (primarily through our watering, I think).

On two occasions (about 6 months apart) we introduced clusters of water hyacinths (as I'm told they help filter the water), but on both occasions they start to die-off about 6-8 weeks later. They are/ were in full sun. Can anyone offer some advice as to why these plants are behaving in such as manner?

A day or 2 ago I also noticed black dark greenish blobs rising to the surface. The blobs look initially like the roughness of a toads' skin, but on touching immediately disintegrate. The sizes of these things are about 5-6cm in diameter. My only thought is perhaps these blobs are perhaps bottom sediment, which we disturbed a few days before whilst moving a couple of the lotus plants. Again, can anyone offer some advice on these blobs, particularly in relation to the quality & suitability of eventually growing & consuming our own fish from this dam?

Tks in advance

Kevin

Edited April 19, 2010 by Crossy
Setfont to defaul for clarity, Crossy

[ozzydom]

Kevin , if you contact the Dept of Fisheries in CM, they will get a field officer to call and test your water for you ,They may be able to offer some helpful advise re placement of fish.

The green /black blobs are algea and usually pop up when water temperature rise, usually fed by nitrates in the pond/water.