Des Moines Water Works Fleur Drive Treatment Plant has the option of three different sources of raw water. The first and best source is a shallow groundwater collection system called the infiltration gallery. It is a three-mile long, porous pipe constructed with concrete rings. This runs parallel to the Raccoon River in Water Works Park, and collects water from the sands and gravels of the river valley. The ponds in the park are also there to help recharge the gallery. It provided all the water to the Des Moines area until 1949.
Increased water demand required construction of an intake on the Raccoon River in 1949, and the drought of 1977 precipitated construction of an intake on the Des Moines River in 1980.
Des Moines Water Works selects its source of water each day, and sometimes can change throughout the day, due to water quality and the ability to treat different substances present in the source water.
Some of the challenges Des Moines Water Works is faced with in selecting the best source water include:
- Availability: The first choice would be the gallery, but most days there is not enough capacity to supply all the water needed, so a second source is needed to supplement the gallery.
- Algae and bacteria: These can cause treatment challenges, such as plugging filters or taste and odor issues.
- Nutrients: Some of these are naturally-occurring in the environment, but most are man-made. They can be from sources such as agriculture, livestock, or wastewater treatment.
- Other: Turbidity (cloudiness of the water), hardness (dissolved minerals in the water), organic material (plant decomposition) or taste and odor.
- Episodic events: There may be an accidental spill or chemical release into the river.
- Cost: The gallery and Raccoon River are available at the Fleur Drive Treatment Plant, but the Des Moines River has to be pumped five miles from the intake to the plant. This adds additional cost when Des Moines Water Works must use the Des Moines River.
Many of the challenges Des Moines Water Works sees changes daily, so monitoring is done continuously. Evaluating the source water and determining what is the best available and at the cost is to treat that source ensure Des Moines Water Works can deliver water you can trust for life.