October 2009 - South Tahoe Public Utility District

Table 5.0: Recycled Water Flow and Quality, 1997-2007.
Total
Total Daily COD BOD SS
NH3-
N
NO3-
N
Total-
P
Cl TDS Turbidity Cl2 Coliform TKN
Year MG MGD mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L NTU mg/L Total Fecal mg/L
97 1,872.3 5.12 37.0 6.9 3.7 19.3 0.25 2.59 50.0 226 2.80 6.12 2.1 2.0 20.73
98 1,693.4 4.64 35.6 6.9 4.0 18.6 0.28 2.56 47.6 227 2.55 4.57 2.1 2.0 21.05
99 1,742.2 4.78 34.8 6.5 3.1 19.3 0.16 2.65 48.8 220 2.42 4.19 2.8 2.0 19.77
00 1,685.9 4.74 42.4 7.9 3.9 20.7 0.04 2.55 53.1 226 2.83 4.53 2.1 2.0 20.89
01 1,565.4 4.29 46.9 8.7 5.1 19.1 0.54 2.87 58.3 241 4.49 5.20 2.0 2.0 21.60
02 1,581.8 4.33 41.2 6.8 3.0 19.8 0.64 2.79 54.8 231 3.70 5.49 2.0 2.0 21.57
03 1,537.5 4.21 45.9 7.8 3.3 22.2 0.10 2.83 57.2 240 4.08 5.69 2.1 2.0 24.20
04 1,483.3 4.05 47.4 7.9 3.8 23.1 0.04 3.19 55.7 242 4.79 6.00 2.1 2.0 26.33
05 1,496.7 4.21 44.9 7.4 3.5 21.1 0.74 3.06 50.6 250 4.30 6.19 2.0 2.0 21.67
06 1,588.1 4.35 47.8 6.6 2.7 21.2 0.07 3.09 48.1 242 4.35 5.95 2.0 2.0 21.66
Permit Max
Concentration
Permit Ave
Concentration
300 45 60 20 240 1
60 30 30 10 23 2
Maximum 1,872.3 5.12 47.8 8.7 5.1 23.1 0.74 3.19 58.3 250 4.79 6.19 2.8 2.0 26.33
Minimum 1,483.3 4.05 34.8 6.5 2.7 18.6 0.04 2.55 47.6 220 2.42 4.19 2.0 2.0 19.77
Average 1,624.7 4.47 42.4 7.3 3.6 20.4 0.29 2.82 52.4 235 3.63 5.39 2.1 2.0 21.95
No. Years 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10
Key
COD = Chemical oxygen demand: an indirect measure of organic compounds in wastewater, and an
indication of wastewater strength.
BOD = Biochemical oxygen demand. BOD is a measure of how fast biological organisms use up oxygen
in a body of water. Similar to COD, BOD is a measure of wastewater strength.
SS = Suspended solids: small solid particles that remain in suspension in water. A low SS concentration
is important because the particles can serve as carriers of pollutants and pathogens.
NH 3 -N = Nitrogen as ammonia. Ammonia is toxic to aquatic life. In its various forms, nitrogen can also
deplete dissolved oxygen in receiving waters, stimulate aquatic plant growth and present a public health
hazard.
NO 3 -N = Nitrogen as nitrate. Nitrate is a primary contaminant in drinking water and high concentrations
can result in oxygen starvation of human cells, resulting in a condition known as methemoglobinemia
(Blue Baby Syndrome).
P = Phosphorus. Wastewater containing nitrogen and phosphorus can cause eutrophication, excessive
growth of plant and/or algae blooms in water bodies.
Cl = Chloride, a measure of wastewater salinity. Irrigation with recycled water high in chloride
concentration can cause the buildup of salts in the soil, impairing the growth of salt-sensitive crops.
TDS = Total dissolved solids: a measure of all inorganic and organic substances in wastewater (generally
less than two microns in size). TDS is an indicator of salinity as well as an array of chemical
contaminants.
Cl 2 = Chlorine. Residual chlorine in wastewater can be toxic to a wide variety of fish and aquatic life.
TKN = Total Kjeldahl Nitrogen (sum of organically-bound nitrogen; ammonia and ammonium in biological
wastewater treatment).
South Tahoe Public Utility District
Recycled Water Facilities Master Plan - October 2009 Page 5-29