In establishing, modifying, or repealing water quality standards the commission shall base its decision upon data gathered from sources within the state regarding the following:

1. 1. The protection of the public health.
2. 2. The size, depth, surface area covered, volume, direction and rate of flow, stream gradient, and temperature of the affected water of the state.
3. 3. The character and uses of the land area bordering the affected water of the state.
4. 4. The uses which have been made, are being made, or may be made of the affected water of the state for public, private, or domestic water supplies, irrigation; livestock watering; propagation of wildlife, fish, and other aquatic life; bathing, swimming, boating, or other recreational activity; transportation; and disposal of sewage and wastes.
5. 5. The extent of contamination resulting from natural causes including the mineral and chemical characteristics.
6. 6. The extent to which floatable or settleable solids may be permitted.
7. 7. The extent to which suspended solids, colloids, or a combination of solids with other suspended substances may be permitted.
8. 8. The extent to which bacteria and other biological organisms may be permitted.
9. 9. The amount of dissolved oxygen that is to be present and the extent of the oxygen demanding substances which may be permitted.
10. 10. The extent to which toxic substances, chemicals or deleterious conditions may be permitted.
11. 11. The economic costs and benefits. The goal shall be a reasonable balance between total costs to the people and to the economy, and the resultant benefits to the people of Iowa.

[C66, 71, §455B.13; C73, 75, 77, 79, 81, §455B.35] C83, §455B.176 2009 Acts, ch 41, §133