OK.  It’s not “simple addition” to figure out the flooding contribution of waste water on the level of Swan Lake.  It’s about as hard as figuring out how much to tip your server.

The Reno Stead Waste Water Plant flows 2.5 million gallons of treated effluent per day to Swan Lake. (Smith)

The Lemmon Valley Waste Water Plant flows 0.22 million gallons of treated effluent per day to Swan Lake. (Smith)

Combined, they flow 2.72 million gallons of treated effluent per day to Swan Lake.

One acre foot is 325,861 gallons.

So, 2.72 million gallons per day is 8.34 acre-feet per day.

Multiply by 365 to get 3,046 acre-feet per year.

The area of Swan Lake is 1,600 acres. (Smith)

Divide 3,046 acre-feet by 1,600 acres.  The result is 1.90 feet per year.

ANSWER: Waste water discharge into Swan Lake raises the level 1.90 feet per year.  

Conclusions

• The effluent discharge into Swan Lake is a significant factor in the lake level.
• It looks like the 2.5 feet of evaporation loss comes from measurements, so this is net of the 1.90 feet of effluent contribution.  Thus the total loss to evaporation is 2.5 + 1.90 = 4.4 feet.  If the effluent were shut off, the lake might fall 4.4 feet during a year due to evaporation.
• If the Reno Stead Waste Water Plant flow increased to 4.0 million gallons per day and the Lemmon Valley Waste Water Plant flow increased to 0.3 million gallons per day, the total would add 3.0 feet to the level of the lake every year.  In this case, the lake level would only lose 1.4 feet per year from evaporation (net).

It looks like the neighbors who assert that the flooding is substantially due to effluent from development are right.

…..

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