Lāʻie-Mauka wetlands are part of an even bigger complex of wetlands situated in central Kīhei. These wetlands are fed by underground springs and the Kēōkea Gulch. All of the buildings that you can see in this aerial image were built onto the original wetland. This development happened in an earlier time when infilling and raising the grade was allowed. This lead of course to the displacement of natural watercourses, and the occasional unintended flooding of surrounding areas.
This low-lying wetland functions as the de facto stormwater catchment and detention basin for this entire area, and holds millions of gallons of stormwater after rains. Many of the surrounding developments divert their stormwater back onto this area, so all rainwater ends up flowing through this location.
This wetland services the local community, and used to have freshwater ponds that the locals would swim in and fish in, but these have been lost over time. This area has been used as an unofficial trash dump too in the past, but thanks to various community-based cleanups, most of the trash has been removed. Maintenance of this area is ongoing and restoration projects will continue. More workdays are scheduled for this site.
You can see by the surface map that the area is a basin that can potentially hold a huge volume of water. Water not only passes over this area after a rain, but it also soaks into the ground here. This area has a huge capacity to absorb rainwater. Undeveloped sites like this have loosely packed soil matrixes that make them especially suitable for absorbing water. Areas like this allow rainwater to reenter the aquifer and reaches the ocean through underground pathways.
Overland Flow of floodwaters: Floods flow across these wetlands. There are several streams directed into this wetland. Massive culverts and engineered streams funnel water into this area. When this becomes too much for the wetland to hold, it spills over into the culverts along South Kihei Road and transits to the Lāʻie Makai Side. In this photo, you can see excess floodwaters spilling over into the con-span (bridge) culvert works.
De facto Detention basin: Of course when the capacity of the land to absorb water is exceeded, rainwater may stand for days or weeks before evaporating. or excess water will sheet off and flow to the areas downslope. In this case, it will cross usually the road through the “conspan culvert works”, and join the Lāʻie Makai Muliwai.
These wetlands are the work-horses of the watershed: Our remaining wetlands have been tasked with managing all of the stormwater runoff and flooding, that comes not only from the surrounding neighborhoods but also all of the flooding coming down from upcountry. Our wetlands do a herculean effort dealing with floods, and filtering dirty floodwaters, but they are gradually being overwhelmed with far too much floodwater. In many cases, more and more tributaries are being channeled into fewer streams, and these streams are diverted into fewer and fewer channels. All this creates a massive load on the few remaining streams and wetlands. These wetlands will not be able to hold back these floods forever, and when they fail all of the contaminated runoff will get dumped directly into the ocean. Ocean pollution is going to get worse with each storm and flood.
Loss of Watershed Infrastructure: Our community relies on a loose network of drainage infrastructure, that heavily relies on open spaces, wetlands, and private property to handle storm waters. There is no county-owned or state-owned drainage system. Most of all of the streams, gulches, floodways, and wetlands are on private property and privately owned. Most of it is not protected from development. That means that landowners can decide to turn our essential streams, and gulches (aka our drainage infrastructure) into houses, condos, or commercial properties. That is why we are seeing a steady deterioration of the watershed, and more extreme flooding. Every year we lose more of our streams and gulches, and wetlands. and these unchecked developments harm the watershed.