Mitigation Wizard Methodology

How we estimate impacts and suggest mitigation opportunities

The Mitigation Wizard can both estimate the impacts of a project based on one or more footprint areas, and it can suggest mitigation for acreage impacts either from the tool's own estimates or from user-entered impact acreages for a range of species or habitats available in our Species Models. These models are described in detail below.

For estimating impacts, we use the full resolution data for each species model tied to a 30-meter "fishnet" grid, each covering 900 square meters or 0.22 acres. We have divided the entire Bay Area up into 30 meter squares and assigned an acreage amount to each square for each species under each model. When you draw, select, or upload a project area, we intersect that area with the fishnet and return the sum of acres for each species, as shown here:

We take a lower resolution approach for suggestion mitigation areas, to avoid false precision and allow for more filter attributes. With a set of 10 hectare (25 acre) hexagons, we attach total habitat acreage for species in each model, along with a range of other attributes. Many of those can be precalculated, such as land protection, land cover, habitat connectivity, and conservation priority (described below).

Other attributes of each hexagon are calculated dynamically as you use the tool. This is true of Habitat Coverage, Species Richness, and Habitat Rarity. Each of these is based on the suite of species you have selected for mitigation, so we can highlight those areas with the most or least habitat coverage, species richness, or habitat rarity for the specific species you have selected. You can use the info icons on each item to read more about how it is calculated.

Species Models

The application relies on several species model approaches and we provide all as options to users to achieve the best outcomes from the tool.

We have models for two purposes:

And then within each purpose, we have models based on several different types of data:

The methodology below describes these options in more detail.

Habitat Preservation Models

For our habitat preservation models, we compiled existing spatial data on the locations of threatened and endangered species, the distribution of land cover or habitats, and the locations of important agricultural lands. The amount of habitat likely to require compensatory mitigation was identified through the following methodology:

Other non-species resources that require offsets if there are impacts are: riparian forest, wetlands, vernal pools, and oak woodlands. These were selected from the land cover dataset.

Habitat Restoration Models

Restoration models used the same approach as the conservation models just described. However, they included several additional land cover types where restoration activity for a species might occur: agricultural areas, barren land, and Eucalyptus groves.

For ecosystem rather than species mitigation, the following methods were used: