The city of Norman recently passed an ordinance limiting the amount of phosphorus applied to lawns. This marks a first for an Oklahoma municipality to address phosphorus loading in a watershed.
The Lake Thunderbird watershed overlaps various communities that surround the lake, including Norman, Moore, and Oklahoma City. Lake Thunderbird receives much of the excess phosphorus through stormwater from overapplication of fertilizer. This contributes to the high amount of algae, which feed on this nutrient.
Lake Thunderbird is a drinking water source for Norman, Midwest City, and Del City. The less phosphorus in the drinking water source, the less treatment the water will need before distribution to the public.
Informational brochures are being prepared by Norman staff, which will distribute them in point-of-sale areas. The ordinance restricts the application of phosphorus fertilizers to the first six months of turf establishment from seed or sod. Exceptions can be made if soil samples from an area indicated that the soil is deficient in phosphorus.