The Des Moines Water Works has announced plans to expand its nitrate removal system, doubling the size of the current facility. This will mean a rate increase for the people of Des Moines.
The current nitrate removal system was built in 1991 at a cost of $4.1 million and is the largest nitrate removal system in the country and perhaps in the world.
In 2016 the system ran for 65 days, costing ratepayers more than $600,000. This year the system was turned on May 2 and according to my water testing, it will run for much of the summer.
Shame on the Iowa Legislature for doing nothing to solve the nitrate problem, and shame on the farm community for not putting more conservation practices in place to reduce farm field runoff.
I tested 15 streams this month as part of a larger testing effort of the Raccoon River Watershed Association. Of those 15 streams, 14 were over the acceptable EPA limit of 10 milligrams per liter (mgm/L).
If the stream being tested has a nitrate reading of more than 10 milligrams per liter (mgm/L), then the stream is considered to be polluted (sometimes called “impaired”). The higher the number, the more polluted the stream.
If the stream is above 10 mgm/L, then it is polluted by all accepted standards. We were only testing for nitrate May 13.
Panther Creek southwest of Adel had the highest reading at 22 mgm/L or more than two times the acceptable limit. It is a very polluted stream.
Nitrate comes from many sources, farm fertilizer runoff, city sewage systems, poor septic tanks, golf courses and some natural processes. The Iowa DNR reports about 80 percent of surface water nitrate comes from farm field runoff.
If the water in the Raccoon River is reading more than 10 mgm/L for nitrate, then the Des Moines waterworks must do extra processing to clean the water and reduce the nitrate to 10 mgm/L or lower in order to be with in federal regulations. This extra processing increases the cost of the drinking water.
Drinking water with a nitrate reading of 10 or more can cause Blue Baby Syndrome in infants. In adults it not clear what the ill effects are. Infants have a type of hemoglobin in their blood that differs from adult hemoglobin, which is the chemical in blood that carries oxygen to our cells. Nitrate blocks the ability of the baby’s blood to carry oxygen, so they turn blue.
In adults, University of Iowa studies have shown a correlation between high nitrates in drinking water and bladder, kidney and urinary cancers. However, this is only a correlation and not definitely proved causation.
Frog Creek was tested north of Perry at Highway 144. It had the lowest reading, maybe because the stream was coming from a marsh or wetland. Marshes and wetlands hold the water, and plants are able to absorb and so reduce the nitrate load.
The transparency number measures how deep (in centimeters) a person can see into the water. It is a measure of the silt load. But forget about the transparency number for now, and just concentrate on the nitrate number.
Testing conducted by the Raccoon River Watershed Association
HUC 12 Tributaries: Raccoon River, May 13, 2017
SITE TIME NITRATES mgm/L Transparency Comments
Frog Ck 9:20AM 5+ mgm/L 35 Cm output of a marsh
Snake Ck 9:35 10+ 30
Snake Ck Marsh 9:40 10 45
Snake Marsh 9:45 5 60 very calm, no current
Buttress Ck 10:55 15 48
Hardin Ck 11:10 20 40
Raccoon R 11:20 20 25
Greenbrier Ck 12:10 18 20 fishing line in tree
Site D1 west of Dawson
Fanny’s Branch 12:25 12 60
Hull Av/160St 14:00 15 60 not a listed site
Elm Branch 14:10 20+ 30 cliff swallows getting
Swan Branch 14:15 20 45 shallow
Mosquito Creek 14:45 18 15 cows access to creek
at Linden Rd
Panther Creek 15:15 20+ 25 mink with baby
Adel dam 15:45 15 — kids in water, water snake