Preliminary maps of the Dominguez Watershed
October 2, 2009 § 1 Comment
For your perusal and comment.
Dominguez watershed with detail from 1896-1902 USGS overlaid.
Here’s some preliminary maps of the Dominguez Watershed, in LA’s South Bay, that I’m working on for Friends/Amigos of the Dominguez Watershed. It’s a work in progress, so I’ll walk you through some of the details.
First of all, the watershed boundary is based on the contemporary watershed, as you can see in the old maps, today’s boundary would also include portions of Compton Creek, for example. As the streams were straightened and culverted or channelized, subdrainage areas were also reconfigured – hence the change.
Dominguez watershed overlaid with detail from 1920s-30s USGS maps. Map is a work in progress.
The next big difference (to me) is that the 1920s-30s era map has so much more detail than the 18906-1902 map. That’s because the later map was drawn at a more refined scale. So we see streams and sumps that I’m classifying as wetlands/vernal pools(in green) that don’t read in the earlier map – but we can bet they were there, research and oral histories indicates it is so. Another big change is that the large Dominguez Slough converted in a mere 30 years to being mostly open water to mostly wetland or sump or wet meadow (see large blue and green areas on the maps). This is the result of deliberate draining of the wetland, today’s Dominguez Channel being the descendant of that earlier effort.
Dominguez watershed today – with some info missing, this is a work in progress.
So in less than 100 years, this has become quite the desiccated little watershed (the white and orange line are the stormdrains, almost no blue anymore, green is a missing layer to be added, but will be small) – to say nothing of polluted. Not covered by these maps is the shift in land use. Wetlands, often being considered a waste (once the hunt clubs have had their fill of the game I guess), get drained for agriculture, and then, being still floodprone, tend to get pretty undesirable zoning – our Dominguez Slough was no different: chemical and petroleum industries set up shop over much of the wetland and today some areas are Superfund sites.
L.A. Creek Freak 
This is fascinating, especially with your written commentary. I would love to see the story completed with a map of the land use shifts you mention. For example a last map showing the industrial zoning and Superfund sites…
a little note: making the browns even more subdued will allow the stream and wetland data to stand out more dramatically. Or– choose one shade of brown and use varied patterning in that same shade (such as stripes, criss crosses, etc) to distinguish the different areas.