Haiku Stream Data: In Situ Data
Summary for July 17, 2026
This week’s monitoring (July 17) showed a mixed picture across our Haʻikū and Huelo sites. Bacteria levels were high at every site sampled, with both E. coli and Enterococcus readings well above EPA recreational safety guidelines. A good reminder to avoid swallowing water and to be cautious with open cuts, especially after the rain we’ve had. Turbidity also varied quite a bit, from 18.7 NTU at Hoʻolawa/Cave Man to a much murkier 92.4 NTU at Honopou, likely reflecting the storm pulse we saw on the Honopou USGS gauge midweek (Healthy stream life <10NTU). On the brighter side, dissolved oxygen stayed within the desirable range at all sites (6.5–7.6 mg/L), and pH held steady in the 6.5–6.66 range across the board. We’ll keep sampling weekly and sharing updates; thanks for your patience in following along with the health of our streams.
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.
