Kulanihakoi Gulch is Being Devastated

Gulch Destruction: This natural gulch is being gutted in the name of debris removal, the project is turning it into a deep square trench that resembles an industrial stormwater drain, not unlike the Los Angeles River. This is a tragedy for the cultural and natural attributes of this important gulch.  This gulch is also classified as a wetland, and is an important named stream.

Hydrological Profile: Kulanihakoi Gulch has a complex and sensitive hydrological profile. This provides not only surface water transport but also surface water infiltration into the groundwater aquifers. Allowing the reduction of surface water (floods) and allowing for the freshwater aquifer recharge. These processes are vital for the natural ecosystems that rely on the nexus of natural freshwater springs and reserves that have evolved over thousands of years. This includes the nearshore coral reef ecosystems that have evolved to rely on SGD (Submarine Groundwater Discharge) from here. 

Sediment Removal: Sediment Removal in wetlands needs to be conducted with sensitivity and with regard to the natural functions, wetland services, and dependent ecosystems. The current methods being used in Kulanihakoi Gulch are engineering overkill, that is, hollowing out the gulch and removing the soil stratas and natural elements that the gulch has created.  The removal of vegetation is destabilizing the soil, and the use of heavy machinery is compacting the wetland soils, which further reduces their ability to absorb rainwater.  

Legal Protections Ignored: This Gulch should be protected by SMA and Wetland Rules that require a full EIS (Environmental Impact Study) that should have been triggered and required to be completed before such work is implemented. But there appears to have been no EIS done to consider these factors. 

Flooding Issues:  Recent Flooding and the closure of South Kihei Road have drawn attention to the Sediment issues in this Gulch, and the sediment removal project appears to have been fast-tracked in the name of reopening transport infrastructure, but the gulch and its wetlands have not been given adequate protections.  Environmental groups have long been warning about the sediment build-up and the need for environmentally sensitive sediment removal work. This should have been done long ago, and should have been done in a sustainable and incremental way. Instead, the sediment was allowed to build up over the years, which allowed increasingly worsening post-storm flooding. These problems are not new. 

Wetlands are Flood Filters: Even with moderate and extreme flooding, the Kulanihakoi Wetlands have functioned as flood filters that have held back massive amounts of debris and floodwater from entering the ocean. One of the main jobs (functions) of the Kulanihakoi wetlands is to catch the sediments and floodwaters and allow them to drain slowly back into the aquifer. The trenching of the gulch impeded the gulch’s ability to catch sediments and store floodwaters, which may lead to increased levels of brownwater and debris entering the ocean. This could lead to increased environmental damage to the coral reefs and marine habitats and ecosystems in the bay. 

Expediency over Environment: The difference now is the availability of federal money, which has resulted in a heavy-handed “fix” that is extremely destructive to the environment. The vegetation and soil layers have been stripped out and discarded, and any potential undiscovered archeological artifacts could have also been destroyed in the process. 

Large-Scale Vegetation Removal: The sediment removal project stripped off the vegetation in a reckless and irresponsible manner. The entire protective layer of vegetation in the gulch was removed at one time. Every tree, shrub, and piece of ground cover was either cut down and/or scraped away. Up to an estimated 20 Acres of vegetation or more were removed, exposing the soil underneath, which allowed it to be swept away in a second flood. This led to one of the worst flooding events on South Kihei Road.

Soil Destabilization: Vegetation such as trees and ground cover hold the soil together, slow floodwaters, and help to capture suspended sediments in floodwaters. This complete removal of vegetation in the lower portion of Kulanihakoi Gulch caused massive amounts of topsoil from mauka and from within the project area to mobilize and flow into the ocean. The removal of vegetation increases surface runoff during storms and exacerbates erosion, as trees and vegetation are known to slow floodwaters and reduce the erosive force of moving floodwaters.

Lingering Harm: The mud clouds in the ocean have still not cleared and may stay around for an extended period, causing harm to the reef and nearshore waters. Large mud deposits in the ocean such as these are a lingering problem, with sediments blocking sunlight and choking filter-feeding organisms. These suspended sediments eventually settle out in a layer covering coral and other organisms, and this same silty sediment can be stirred up by wave action and reactivate a turbid debris cloud in the water, blocking sunlight again, spreading around, and smothering more marine life. These deposits can cause lingering harm for six months or more. The long-term effects of these sediment deposits are not fully understood and may potentially cause harm for years to come or likely cause permanent changes to the marine ecosystems.

 

ADDITIONAL READING:

https://savethewetlands.org/kulanihakoi-gulch-stream/

https://savethewetlands.org/kaonoulu-kulanihakoi-wetlands/