Reduce Irrigation in Ankeny, Des Moines Water Works Says

FROM CITY OF ANKENY

ANKENY, Iowa (July 15, 2013) - Meeting customer demand during this period of highly polluted river waters is very difficult. Des Moines Water Works and neighboring metro area communities who receive their water from Des Moines Water Works are asking customers to reduce irrigation in light of persistently high nitrate concentrations in the Raccoon and Des Moines Rivers, two primary sources of water for Des Moines Water Works. Customers are asked to lower the volume of irrigation water used by reducing the amount of time sprinklers run, and to irrigate on odd or even days. For example, if a customer's address ends in 1, 3, 5, etc., lawn watering is acceptable on odd days of the month and vice-versa for even addresses.

While water quantities in the rivers are plentiful, record-setting nitrate concentrations in the rivers require extensive treatment within Des Moines Water Works' Nitrate Removal Facility-a facility that is currently operating at maximum capacity. Customer demand is currently at 70 million gallons per day (MGD) and trending upwards due to increased irrigation. Over the past two months, Des Moines Water Works has been operating the nitrate removal facility and using alternate water resources that are lower in nitrate levels, including Maffitt Lake, Crystal Lake, Aquifer Storage and Recovery (ASR) wells, and the utility's underground infiltration gallery. However, these alternate sources are not adequate to meet increasing irrigation demand and Des Moines Water Works began pulling water from the Des Moines River last Saturday, July 6th. If high nitrate levels persist and irrigation demand does not ease, Des Moines Water Works will be unable to meet the Maximum Contaminant Level (MCL) of 10 mg/L for nitrate set by the US Environmental Protection Agency (EPA).

"Absent an extraordinary situation, it's not a good business model to ask customers to reduce their demand for water," said Bill Stowe, CEO and General Manager of Des Moines Water Works. "It's a decision we have arrived at only after much thought, both in terms of the inconvenience to our customers and the impact to our revenue base. We are asking our customers to help us manage through these unprecedented circumstances by reducing their irrigation until nitrate concentrations decrease in our source waters."

June set records for nitrate concentrations in the Raccoon and Des Moines Rivers, with nitrate concentrations of 24.39 mg/L and 18.72 mg/L, respectively. Nitrate loads in the rivers also set records in June, with the Raccoon River reaching the highest nitrate load level ever of 12,041 metric tons, breaking the previous record in May 2007 of 8,731 metric tons. The Des Moines River reached the third highest nitrate load level with 14,869 tons. The record for the Des Moines River was set in June 1991 at 16,840 metric tons.

Safe drinking water for 500,000 central Iowans has come as a result of operating the nitrate removal facility for over two months, operation that comes at a cost to Des Moines Water Works' customers. As of June 30, 2013, Des Moines Water Works has spent $375,000 operating the nitrate removal facility to ensure the MCL was met. Operation of the nitrate removal facility will continue as long as nitrate levels persist.

Increased nitrate levels and warm temperatures can also trigger the growth of algal blooms, the presence of which presents additional treatment challenges in the form of clogged filters and extended treatment periods.

The greatest health risk posed by high nitrate concentrations is for infants under six months of age. Nitrate can reduce the ability of the baby's blood to carry oxygen, which may result in Blue Baby Syndrome. Nitrate concentrations in Des Moines Water Works' finished drinking water has not yet exceeded the level that will cause these health complications. If you have health-related questions, talk with your medical provider.