Revegetation is a critical part of stormwater management to eliminate or reduce pollutant loading into streams by providing soil stabilization for post construction sites. The main emphasis for controlling stormwater generated pollutants is by the design, installation and maintenance of best management practices, otherwise known as Control Measures. Regulatory agencies such as EPA, the Colorado Department of Public Health and Environment (CDPHE) and other state agencies provide very little if any regulatory compliance enforcement and proper guidance on project revegetation.
According to CDPHE, uniform revegetation is required after construction activities have been completed. In order to terminate a CDPHE construction stormwater permit, revegetation that is measured by vegetative cover must achieve a level of cover that is 70% of pre-construction or baseline conditions. In order to measure this 70% level, an initial baseline vegetative cover determination must be conducted before construction starts.
It is interesting to note that CDPHE does not have specific revegetation establishment and monitoring guidance that addresses the introduction and establishment of noxious weeds. (www.colorado.gov/pacific/sites/default/files/memo%20on%2070%20percent%20stabilizationpdf). As a result, vegetative cover provided by noxious weeds is acceptable by CDPHE for post construction revegetation construction; therefore, there is little incentive for construction permittees to initiate and more importantly maintain native plant species during revegetation.
This approach seems contrary to the State of Colorado Noxious Weed Program (www.colorado.gov/pacific/agconservation/noxiousweed) in which the program mission is to control noxious weeds, the non-native aggressive invaders that replace native vegetation, reduce agricultural productivity, cause wind and water erosion, and pose an increased thread to communities from wildfire. Noxious weed management is done by preventing the introduction of new invasive species; eradicating species with isolated or limited populations; and containing and managing those invasive species that are well established and widespread.
I doubt that this issue is just a Colorado problem and is probably wide spread throughout the nation.
It is urged that CDPHE, EPA and state agencies develop specific revegetation criteria that promotes and requires the establishment of native and/or noninvasive species before a stormwater permit can be terminated. Noxious weeds should not constitute appropriate vegetative cover for stormwater management. In addition to noxious weed management, baseline and uniform post construction vegetative cover determinations should be audited for compliance and adequacy.