values of the Bay. Then we require mitigation to offset those 
unavoidable impacts. Federal agencies often refer to this type 
of mitigation as compensation. 
Now determining the adverse impacts of a small amount of 
fill in the Bay, particularly if marshes and mudflats are not 
involved, is very difficult. It is probably impossible to 
quantify precisely such impacts. However, we can reasonably 
assume that the cumulative impacts of several small fills, will 
at some point, affect the natural values of the Bay, even though 
it is difficult to assess the impacts of each small fill. Never¬ 
theless, the best available environmental information must be 
provided, preferably in a document that clearly describes the 
site and project. Certainly biologists, hydrologists, and 
perhaps other scientific specialists should be involved in 
obtaining and evaluating that information. 
When that information shows that there is an adverse impact 
that is unavoidable, it should be offset. Usually, this should 
be done by reopening an area to tidal action or enhancing the 
wetland values of an area that may not be sufficiently flushed 
or drained or may not contain as much diversity of habitat as 
biologists tell us is desirable. We have also found that it is 
crucial to consult with scientists when reviewing plans to 
change an area, particularly if areas are to be reopened to 
tidal action, new wetland vegetation is to be established, or 
other enhancement actions are to be taken. 
Diked historic baylands is another recent study that in¬ 
volved scientific research and opinion. Prior to the Commis¬ 
sion's creation, substantial areas of the bay were diked off. 
Many of these areas were converted to saltponds but many others 
were used for hay growing, grazing, and similar agricultural pur¬ 
poses. These areas retain some wetland values and are often 
quite important for waterfowl and other animals that use both 
the Bay and uplands. Diked baylands are under pressure for 
urbanization. On the other hand, they present the last opportu¬ 
nity to significantly improve the habitat values of the Bay. 
In undertaking the diked historic baylands study, the Com¬ 
mission again turned to the scientific community to discover how 
these areas functioned and what beneficial changes could occur. 
We discovered a great deal about the species that now use the 
areas, about the compatibility of agricultural and wildlife use 
of many of the areas, about the difficulties of modifying such 
areas, and about the flood plain and soil values of these 
areas. Based on the valuable scientific information and 
opinion, the Commission found that diked historic baylands had 
great importance as part of the Bay system and adopted findings 
and policies to use when projects were presented to the Corps. 
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