A local problem with local solutions.
By John Starmer
Polluted runoff, the often-untreated murky brown water that oozes out into Maui’s ocean after every large storm, contains a toxic stew of oil, gas, fertilizers, pesticides, pharmaceuticals along with plastics, animal waste, detritus, sand, soil and rocks The technical name for this toxic soup is “Nonpoint Source Pollution” because there is no single polluting source, even though it often flows into the ocean co-mingled together via rivers and gulches.
This mystery mix of pollutants that come along for the ride are why DOH issues “Brown Water Advisories” and even closes down beach access when water quality standards are violated.
People can and do get sick from swimming in polluted water, but marine life living along our coasts can’t or won’t get out of the way.
When an area gets polluted by NPS, some fish and birds may just leave an area when water quality becomes too toxic. Most of the species found on coral reefs, however, are either permanently stuck to the bottom or don’t move quickly or far enough to get out of the way of a plume of polluted runoff and end up soaking in it.
Corals suffer horribly from the effects of NPS pollution. While they are animals, they rely for most of their food from single celled algae, called Zooxanthella, that the corals farm inside their bodies. The shading caused by muddy water reduces the amount of food the algae can share with their host coral and can cause the Coral to weaken and then die off.
Along with muddy silt, a wide range of chemicals make their way into the water too. Oil, antifreeze, and other chemicals wash off roads and parking lots, and the heavy rains deliver them into marine ecosystems.
Herbicides and pesticides, especially when mixed together, often act as endocrine disruptors (chemicals that act as artificial hormones) and these can interfere in myriad ways with marine animals development and reproduction.
Chemical fertilizers, both those applied on farms and for landscaping, along with waste from wild and feral animals, also can cause problems when the nutrients spur algal growth. Although added fertilizer can reduce light by causing algal blooms (and remember corals need that light), the bigger problem in Hawaii is that these nutrients allow invasive algae to grow faster than native coral reef species. In the worst cases, these algal blooms completely cover the bottom, and simply smother the more slowly growing corals and native algae.
Finally, animal waste in particular is a serious health concern. While contact with contaminated water can cause minor infections and disease, the consequences of swimming in this type of pollution can be fatal. For example, Leptospirosis, a bacterial infection that can infect mammals, survives in freshwater, mud and soil. Leptospirosis infections haves killed people in Hawaii and the Leptospira bacteria has infected marine mammals.
Toxoplasmosis gondii is a single- celled protozoan parasite carried by cats. While the infections in humans are generally mild, the CDC reports that 40 million people in the US carry toxoplasmosis, and it can cause severe consequences for both the immunocompromised and also pregnant women. On Hawaii, its greatest impact, however, is that it infects and can kill the `Ilio holo I ka uaua or Hawaiian Monk Seal. NOAA Fisheries considers this disease to be a leading cause of death in this critically endangered species.
What can be done about NPS pollution?
The challenge of NPS pollution is the “nonpoint” part. Dealing with polluted runoff means tackling each and every source that need to be addressed. NPS pollution problems are best managed at the watershed level. A watershed is an area of land that drains into the ocean or a lake from a single source. If you drive around Maui, each stream and gulch drains its own watershed. Because more important watersheds flow from the highest ridges of an island down to the reefs, this management approach is sometimes called mauka (mountains) to makai (ocean).
The Maui Nui Marine Resource Council’s (MNMRC) “Vision for Pohakea” management plan is one example of watershed-based action. For example, the Pohakea watershed covers an area that starts along the ridge by the West Maui windmills and drains into Ma’alaea Bay.
According to Amy Hodges, MNMRC’s Programs and Operations Manager, the primary focus of their plan was to reduce the sediment being delivered into Maalaea Bay by stormwater runoff. The MNMRC Council has initially focused on fire suppression in the watershed, as plant cover is critical to keeping soil on the mountain. Addressing erosion problems from existing dirt roads and plowing firebreaks to both help contain fire from spreading and allow fire fighters access have been primary project accomplishments so far. They have also planted Vetevier grass in erosion- prone areas as it is both fire resistant and is an excellent soil stabilizer. Hodges stated the goals is, “to see fewer, smaller and more controllable fires in the watershed.”
Future goals for the project include reducing erosion within the gulches and possibly creating ponding basins mauka to keep the soil that does erode from reaching the ocean.
Another non-profit with a watershed focus is the Save the Wetlands Hui. They are working to raise awareness, protect, and restore the function of wetlands in Kihei. The group’s initial efforts have focused on the Laʻ’ie wetland in central Kihei with volunteers working to remove invasive plants and trash and restore native plants owned by private landowners.
Robin Knox, an environmental professional and the owner of Water Quality Consulting, Inc., serves as the Hui’s project manager at this restoration site. She noted that while bringing back native habitat and wildlife to the area is certainly a goal, the Hui is hoping to see the wetlands in the area restored so that they are able to “filter” stormwater coming down the watershed from Haleakala’s slopes and keep sediments and other pollutants from getting even near the ocean.
In addition to acting as natural settling basins by slowing down water flow, Knox pointed out that the functioning wetlands also naturally remove nutrients and keep other pollutants from reaching the sea.
There is no one perfect solution, but knowing how important a healthy coral reef system is to the marine environment, and how foundational they are to the food resources that residents and visitors to the islands rely on, we must make every effort to preserve and protect our reefs.
Save Maui Wetlands Hui
Maui Nui Marine Resource Council
Mauna Kahālāwai Watershed Partnership
East Maui Watershed Partnership
Auwahi Forest Restoration Project
Waihe’e Coastal Dunes and Wetlands Refuge
Coral Reef Alliance