Compensatory Mitigation Overview
It is likely that you might not think about the planning and regulations behind land development while you’re traveling on the highway or visiting a favorite shopping plaza. Large scale projects such as these typically involve years of planning and foresight and is often impossible to construct such projects without impacts to Waters of the United States (i.e. streams and wetlands). When an entity applies for a Clean Water Act (CWA) Section 404 permit, they are required to perform compensatory mitigation if they plan to impact a tenth (0.10) or more of an acre of wetlands or 300 linear feet or more of streams. Compensatory mitigation involves the restoration, enhancement, creation, and/or preservation of streams, wetlands, and other aquatic resources to offset unavoidable adverse impacts. Entities are normally only granted a 404 CWA permit once practicable aquatic resource avoidance and minimization measures have been demonstrated in the permit application. Such restorative measures are required under federal law and defined in the 2008 Final Compensatory Mitigation Rule (33 CFR Parts 325, 332; 40 CFR Part 230). According to the 2008 Final Rule, permittees have three options to create required mitigation including:
- the purchase of credits from a mitigation bank (most preferred),
- Utilizing the established In-Lieu-Fee program,
- and permittee responsible mitigation.
Mitigation banks are projects undertaken by “Sponsors” in which they establish and document existing ecological site conditions and then typically restore or improve the site and protect the site forever from future development through deed restrictions such as a conservation easement. Aquatic resource improvements (i.e. ecological lift) are measured through certain metrics to create credits, which are then released for sale to entities with projects requiring mitigation in the same watershed. In West Virginia (WV), ecological lift (credits) and ecological impacts (debits) are assessed using the WV Stream and Wetland Valuation Metric to ensure consistent comparisons between aquatic resources being impacted and aquatic resources being improved through mitigation projects to achieve no net loss of streams and wetlands.
Hackers Creek Mitigation Bank
AllStar Ecology, LLC (ASE) completed construction in early 2019 of its first mitigation bank along unnamed tributaries of Hackers Creek in Upshur County, West Virginia. When searching for a mitigation bank site, it is preferable to find land that has been historically impacted in order to increase ecological lift and provide more environmental benefit. The Hackers Creek Mitigation Bank site presented ideal conditions for restoration and enhancement of streams/wetlands due to historic impacts of mining, logging, and cattle grazing. Stream reaches within the project area were severely degraded and essentially eliminated in sections due to legacy mine benches, logging roads, and cattle grazing. Relic road grades significantly altered drainage patterns and the floodplain resulting in rerouting of overland flow and disturbance of floodplain topography.
In order to successfully restore and enhance streams/wetlands, ASE conducted baseline surveys of all existing streams and wetlands to fully understand the physical, chemical, and biological conditions of these features to determine the necessary improvements. Additional baseline impairment surveys were also conducted to assess the geomorphic conditions of existing streams such as pattern, profile, and dimension, as well as degree of impairment with regard to entrenchment, incision, and lateral instability (width/depth ratio). ASE then took this baseline data and designed stream channels and wetlands based on Natural Channel Design techniques pioneered by stream restoration expert, Dr. Dave Rosgen. By understanding the level of impairment and degree of departure from stable reference stream conditions, ASE was able to design geomorphically stable stream channels that would increase aquatic habitat (i.e. undercut stream banks, deeper pools), raise the water table (thus increasing wetland conditions), and develop self-sustaining ecosystems with no required long-term maintenance.
The Hackers Creek Mitigation Bank is comprised of two sub-watersheds. One sub-watershed was significantly impacted by a road which channelized a perennial stream against the hillslope. This is a common practice in watersheds historically utilized for agriculture given the increased area for grazing and hay production resultant of the straightened stream. However, although stream channelization may be beneficial to agricultural production, biologic and geomorphologic functions are significantly degraded due to channel incision, which is characterized by vertical-containment and floodplain abandonment. In essence, channelization is a short-term solution to increase agricultural land, because the resulting incision usually accelerates stream bank erosion and associated land loss. Furthermore, such channelization goes against the geomorphic tendencies of low-gradient streams which, under natural conditions, meander across the valley bottom, allowing for energy dissipation, increased nutrient retention, and the establishment of riparian vegetation.
By understanding the impairments associated with the mitigation site, as well as the ecological potential through reference stream surveys, ASE successfully designed and constructed a high-quality ecosystem that will achieve long-term geomorphic stability.
The AllStar Ecology Difference
ASE designed and constructed the Hackers Creek Mitigation Bank by relying upon our experienced multidisciplinary team of ecologists, geologists, landscape architects, soil scientists, and equipment operators. ASE invests heavily in employee training, especially relating to stream and wetland restoration. Numerous ASE employees have been trained by Dr. Dave Rosgen as part of his natural channel design courses with several attaining Level IV certification.
ASE is utilizing a watershed approach to stream and wetland mitigation by continuing to develop a series of mitigation properties in the Hackers Creek watershed. Restoring headwater systems in a watershed with significant historic impacts will result in long-term ecological benefits that go beyond compensation for stream and wetland impacts. ASE’s watershed approach, combined with successful and meaningful mitigation projects, will benefit present and future generations through watershed protection, habitat restoration, and preservation of headwater systems. Learn more about ASE’s stream and wetland restoration services by clicking here.