“It’s a very counter intuitive design,” Sturtz said. “We’d love to use a tree fall. We want to get away from taking everything in a stream and removing it. Obviously, we want our streams to be natural.”
There are over 300 miles of stream corridors in Norman.
O’Leary said if the city moves forward with a storm water utility fee and it is approved by voters, the fee would provide a funding source for future work in this area.
On a Merkle Creek tributary severe erosion was treated with ScourStop and turf reinforcement mat rather than using a concrete liner. ScourStop mats are made of a polymer that protects the soil from erosion. The green mats have holes that allow vegetation to grow through, helping to anchor the soil, providing a buffer from erosion and a filter for pollutants.
Local builders are already starting to use low impact development infrastructure. Examples include the Carrington Lakes Addition and Trailwoods.
“You have to educate all people — even your own maintenance people,” O’Leary said.
In one instance a builder had maintenance mow plantings that had been put in to create a rain garden effect. In other instances, the city has had staff mow wetlands and trees.
But the ideas are catching on.
Many Norman codes and ordinances support low impact development including the landscape ordinance with buffers along arterial frontage and recommended plant materials that are drought resistant. Detention requirements, engineering and design criteria and standards and the water quality protection zone are among Norman’s proactive measures to lesson the impact of development and use the natural environment to protect stream corridors and the lake’s watershed.
The city’s fertilizer ordinance has become particularly important as the city moves to comply with new standards based on the recent TMDL study done on Lake Thunderbird.