permaculture

[Thomas Allen <thallen@nwlink.com>]

The table below if from a report I did on water quality in a  
municipal storm water detention pond in a suburb of Seattle. Rainfall  
for water year 2006-07 was 51.76 inches. There is some effect of  
runoff from yards and streets but the figures aren't much different  
for the outlet of a sand filter downstream of the pond. I also  
monitor a bog wetland to see what effect the development is having on  
the bog. So far, the county has opted not to dump residential storm  
water into the bog. Not suprisingly, pH levels are much lower in the  
bog, on the order of 4 or less at times.

--Tom Allen


Table 3.3.1 Synopsis of water quality findings for location WQ2
Constituent

Minimum Value

Maximum Value

Average Value



pH

5.80

7.30

6.08

Temperature, deg. C

0.50

14.90

8.58

Conductivity, umohs/cm

25.60

45.60

35.84

Spec. Conduc., umohs/cm

44.10

63.40

52.91

Salinity, ppt

0

0

0

DO, mg/l

1.15

9.54

2.87

TSS, mg/l

1.00

13.00

3.00

TP, mg/l

0.01

0.05

0.04

Calcium, mg/l

2.80

5.00

2.80

Nitrate + Nitrite, mg/l

0.02

0.47

0.02

TKN, mg/l

0.15

0.79

0.64

Ammonia N, mg/l

0.01

0.12

0.11

Alkalinity, mg/l

12.00

18.00

12.00

Chloride, mg/l

1.00

7.00

2.50

Sulfate, mg/l

1.20

3.70

3.70

Magnesium, mg/l

1.40

2.40

1.40

Potassium, mg/l

0.35

0.77

0.42

Sodium, mg/l

1.50

2.40

1.70




On Oct 5, 2008, at 8:34 AM, Toby Hemenway wrote:

> Paul, hurray! You actually did the experiment! Enough hearsay,  
> let's get
> some data.
>
> 7 ppm is a respectable brew, though. Enough to kick the water from pH7
> to 5.7, or about 20-30 times more acidic (log scale, right?). And 7  
> ppm
> is the effective dose for some herbicides, vitamins, and a lot of  
> other
> stuff--a thousand times more than what's needed for hormones or  
> dioxins.
> It means that in a 120,000 gallon tank there'd be about 8 pounds of
> stuff suspended in it, if my math is right. A fair amount.
>
> Mollison does exaggerate a bit (as usual) when he calls rainwater a
> soup, but it adds up. That forest in New Hampshire I mentioned  
> earlier,
> that's getting 8kg calcium per hectare from rain: figure a meter of  
> rain
> a year over a hectare, that's 10,000 cubic meters, or 10 million  
> kgs of
> water with at least 8kg, or 0.8ppm calcium suspended in it (surely  
> a lot
> more, since the 8kg is just what's taken up by the forest), but it's
> enough to supply sufficient calcium to feed a forest. So even a thin
> soup makes a difference.
>
> I'd be curious to see what pondwater, municipal water, wellwater, and
> other less than pristine waters have for TDS.
>
> Thanks for the numbers!
>
> Toby
> http://patternliteracy.com
>
>
>
> Paul Cross wrote:
> > It is raining tonight in the mountains of north central New Mexico  
> > USA.
> > With so much talk of water on the list lately, I thought I'd measure
> > mine. Coming off the roof of the greenhouse and running down the  
> > dirty
> > gutters the water has
> >
> > 7 parts per million total dissolved solids
> > 5.7 ph
> > 14 millimhos electrical conductivity
> >
> > Makes me want to measure some distilled water for comparison.
> >
> > I hear a lot of talk about rainwater containing a lot of "stuff"  
> > in it.
> > Every time I have measured it at my house, it doesn't appear to have
> > much in it.
> >
> > Paul
> >
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