Haiku Stream Data: In Situ Data
Summary for August 31, 2026
Testing on August 31 found bacteria levels above safety guidelines at several sites. Honopou and Hoʻolawa/Cave Man exceeded guidelines for both E. coli and Enterococcus, and Hoʻolawa/Twin Falls exceeded guidelines for both as well (E. coli just at the threshold, Enterococcus above it). At these sites, we recommend avoiding contact with open cuts, not swallowing stream water, and showering after swimming. Naʻiliʻilihaele/Bamboo Forest and Kailua/Dog Pond again had the lowest bacteria readings, both within safe guidelines. Hoʻolawanui also remained within safe bacteria guidelines.
Regarding the health of our aquatic life, turbidity was low across all sites this round, ranging from 3.1 to 7.0 NTU, a notable improvement from prior sampling and well within the recommended threshold. Dissolved oxygen, pH, and temperature remained within healthy ranges at all sites.
General Info on Data
Turbidity
Turbidity is a measure of water clarity. Higher turbidity indicates cloudier water caused by suspended particles such as sediment (silt and clay), organic matter, or algae. These particles can enter streams through rainfall and erosion or through runoff from disturbed land, agriculture, and roads. High turbidity can reduce sunlight in the water and may carry nutrients, bacteria, and other pollutants attached to sediment, making it an important indicator of overall stream health.
Dissolved Oxygen
Dissolved oxygen (DO) is vital for the survival of fish, aquatic plants, and other organisms. Just like humans need air to breathe, aquatic life depends on dissolved oxygen for survival. Healthy high dissolved oxygen levels indicate a well-functioning ecosystem, while low dissolved oxygen levels can signal pollution and poor water quality. Low dissolved oxygen levels can also lead to the proliferation of harmful bacteria and algae, making the water unsafe for swimming, fishing, and other water activities. While a single “typical” dissolved oxygen (DO) level isn’t applicable across all Hawaiian streams, a generally desirable range for healthy streams falls between 6 milligrams per liter (mg/L) and 8 mg/L, because this range supports a variety of aquatic life.
Conductivity
Conductivity measures the amount of dissolved salts and minerals in water and can help identify potential water quality concerns. Higher conductivity can occur naturally in streams that flow through mineral-rich soils and rocks, but it can also increase due to human activities such as road runoff, fertilizer use, or wastewater discharge. Elevated conductivity may signal the presence of pollutants, including dissolved metals and other contaminants, that can affect stream health and pose risks to people using the water.
Water pH
pH is a measure of acidity (or basicity) on a scale from 0 to 14, with 7 being neutral. Freshwater streams should ideally have pH levels between 6.5 and 8.5 to support aquatic life and be safe for recreational use (U.S. Environmental Protection Agency [EPA], 2022). Deviations from this range can indicate the presence of pollutants or other environmental issues that may harm aquatic organisms and pose risks to human health.
Enterococcus and E. Coli
E. coli and Enterococcus are indicator bacteria used to assess water quality. While they do not always directly cause illness, their presence can signal fecal (poop) contamination and suggest that other harmful pathogens may also be in the water.
Health risks associated with fecal contamination can include gastrointestinal illnesses such as diarrhea, nausea, vomiting, and stomach cramps. Exposure may also lead to ear, eye, or skin infections, and in some cases, more serious illnesses such as hepatitis A or other viral infections.
Animal waste from livestock or wildlife can contribute to bacterial contamination in streams and may introduce pathogens such as Salmonella, Campylobacter, and Leptospira, the bacteria that cause leptospirosis.
In tropical environments like Hawaiʻi, these bacteria also persist naturally in warm soils and sediments, meaning they may sometimes be detected even when recent fecal contamination has not occurred. However, elevated levels still indicate that potentially harmful pathogens could be present in the water.
