The HMP (or Hazard Mitigation Plan) standard was defined following the 1983 and 1986 floods with the goal of establishing a minimal, short-term interim standard that would lessen the likelihood of repeat damages from flooding. The HMP standard was supposed to be implemented for all Delta levees by 1991 as a precondition for receiving FEMA disaster assistance; however, although many local agencies have complied, even 25 years after the deadline, the HMP standard has not yet been achieved for all Delta levees. FEMA does deny disaster assistance claims if an island’s levees are not in strict compliance.
The HMP standard provides a very marginal or basic level of protection that is hardly suitable for agricultural areas with permanent crops or critically-important habitat that could be wiped out by flooding. It was not intended to be a long-term standard when it was established, and it is not an adequate standard for any land use that is intended to avoid flooding,