Stormwater policy is put in place to control non-point source pollution and is usually tied to the National Pollution Discharge Elimination System Permit (NPDES).
Implementation tends to take a while – not for a lack of desire to protect our water resources, but because it is often challenging to integrate stormwater policy through the existing local political structure. Planning and zoning codes, public work drainage infrastructure requirements, and public health and safety standards (to name a few) can all potentially be affected by changes to stormwater policy.
For example, it took approximately 15 years to make changes to the original Clean Water Act (1972) and address pollutant concerns directly associated with stormwater (1987). It took another 15 to 20 years to integrate these stormwater requirements into the network of permits and ordinances, and develop the tools necessary to assist stormwater designers.
To completely convert stormwater policy into a usable format, a Stormwater Management Manual is often the best solution.
Integrating generic stormwater policy without accounting for technical requirements or variability in geographic conditions can have a tendency to delay policy implementation. For example, in Washington State by 2010 there will be over a dozen different technical manuals for stormwater management. Although these technical manuals have undergone substantial additions and account for local conditions, the net results essentially are expanded source control and increased facility size for flow control (detention) and/or water quality treatment. While providing additional water quality protection, it also increases the overall cost for developing new infrastructure.
One benefit of Stormwater Management Manuals is that they can be updated as new regulatory policies emerge, providing an easier avenue to integrate policy changes.
Rather than requiring an ordinance or code revision, which usually requires a non-technical city or county council to approve, municipalities can make changes to these technical design manuals through frequent updates with less political hurdles.
Policy changes have already begun to take shape before the ink is dry on many of these technical stormwater manuals.
As we continue to develop stormwater policies for the ultra-urban landscape, we may need to take a step back and evaluate stormwater from a more holistic approach. Low impact development design principles, which incorporate natural drainage features and provide groundwater recharge, have already changed the landscape for how we are planning sites. Although we want to be environmentally responsible, we need to encourage redevelopment within the urban setting as much as possible, prior to developing existing green fields. If we only provide incentives to use low impact development, we may end up ignoring existing problems and add to urban sprawl where it is easier to accommodate many of these techniques.
As we continue to expand new policies, we should also begin considering the broader aspects of our overall impacts, not just those attributed to stormwater.
We need to begin shaping our concepts of the overall site towards a “net zero” impact balance. As we continue to modernize design, the basic principles are not necessarily to lower the stormwater impact through onsite mitigation, but to completely neutralize as much of the anthropogenic impacts (energy, carbon load, water use, etc.) as possible. Planning for a zero impact in the ultra-urban setting will ultimately provide the best type of environmental site design.