Missing multipolygon after ImpOSM import to PostGIS

Question

I've been testing ImpOSM 2.5.0 with an extract of Washington State (in the U.S.) and am very impressed with the overall result. However, I noticed that fairly prominent lake was missing from the resulting "osm" DB, so I started to dig a bit deeper. I confirmed that the lake is present in the extract, here are it's details:

    <relation id="411923" version="13">
            <member type="way" ref="42114354" role="inner"/>
            <member type="way" ref="42114348" role="inner"/>
            <member type="way" ref="42114344" role="inner"/>
            <member type="way" ref="42114346" role="inner"/>
            <member type="way" ref="42115602" role="inner"/>
            <member type="way" ref="42117265" role="inner"/>
            <member type="way" ref="42125939" role="inner"/>
            <member type="way" ref="52374472" role="outer"/>
            <member type="way" ref="126149886" role="outer"/>
            <member type="way" ref="126149894" role="outer"/>
            <member type="way" ref="52434337" role="outer"/>
            <member type="way" ref="126263156" role="inner"/>
            <tag k="name" v="Moses Lake"/>
            <tag k="natural" v="water"/>
            <tag k="source" v="yahoo_wms"/>
            <tag k="type" v="multipolygon"/>
    </relation>

I then checked the DB table definition in geometryc_columns and saw this:

osm=# select * from geometry_columns where f_table_name like '%water%'; f_table_catalog | f_table_schema | f_table_name | f_geometry_column | coord_dimension | srid | type
-----------------+----------------+-------------------------+-------------------+-----------------+--------+------------ | public | osm_new_waterways | geometry | 2 | 900913 | LINESTRING | public | osm_new_waterareas | geometry | 2 | 900913 | GEOMETRY | public | osm_new_waterareas_gen1 | geometry | 2 | 900913 | GEOMETRY | public | osm_new_waterareas_gen0 | geometry | 2 | 900913 | GEOMETRY

The GEOMETRY type is new to me, but I assume that it is a valid type to store polygons/multi-polygons.

I followed the tutorial at http://imposm.org/docs/imposm/2.5.0/tutorial.html and had no problems with any of the steps listed there, but I'm curious if given the nature of this feature, should I have done something more to enable it to be parsed from the extract and created in the DB?

Many thanks for any clues you can provide.