Fig. 4. The Elkhorn Slough regional greenprint and mitigation portfolios, as identified through the MARXAN runs. The upper image is the regional conservation potfolio using representation targets set by the local environmental group, the Elkhorn Slough Foundation. The lower image is a portfolio of sites that could meet the mitigation needs for four Caltrans projects planned in the watershed. The darkest-blue parcels contain biological resources that are limited, and thus, are more difficult to substitute for other parcels. The lighter parcels may be just as highly suitable, but the resources they contain could be found on other parcels. In the lower map, any parcel with a color other than tan, can be thought of as a candidate for fulfilling mitigation obligations.