EBCI Water Quality — E. coli (Rivers & Streams)

Map of Sampling Sites

Status uses EPA’s 2012 Recreational Water Quality Criteria for freshwater E. coli (GM 126; STV 410 CFU/100 mL). Learn more: https://www.epa.gov/wqc/recreational-water-quality-criteria-and-methods

How status is determined (EBCI standards)

The Eastern Band of Cherokee Indians’ Water Quality Standards (WQS)—adopted under Cherokee Code Chapter 113E—designate Recreation and Ceremonial Use for many surface waters. For freshwater, the bacteria criteria are:
• Geometric mean (GM) of E. coli over a 30-day period ≤ 126 CFU/100 mL, and
• No more than 10% of samples in the same 30-day period exceed 410 CFU/100 mL—the Statistical Threshold Value (STV). These values align with the U.S. Environmental Protection Agency’s Recreational Water Quality Criteria (RWQC, 2012).

Good — Meets EBCI WQS for Recreation/Ceremonial Use: the site’s 30-day GM < 126 and the latest sample < 410 CFU/100 mL.
Caution — Latest sample 235–409 CFU/100 mL (approaching the 410 STV) while the 30-day GM remains < 126. Short-lived spikes often follow rain/runoff; consider postponing water contact for 24–48 hours.
Advisory — Either the latest sample ≥ 410 CFU/100 mL or the 30-day GM ≥ 126. Avoid swimming/wading where posted; higher-risk groups (young children, older adults, immunocompromised) should take extra care.

Why GM and STV? The GM reflects typical conditions over the last 30 days; the STV (410) controls high single-day results. EPA notes that about five samples in 30 days is ideal where feasible.

Monitoring frequency. Sites are sampled regularly during the primary recreation season (approximately April–September) as staffing, safety, and river conditions allow. Additional sampling may occur after rainfall/runoff or when conditions warrant.

Latest Results

How status is calculated: Status uses the latest sample and, when available, the 30-day geometric mean (GM). The GM rule applies only when there are ≥2 samples in the last 30 days. Advisory is shown if latest ≥ 410 CFU/100 mL (EPA single-sample Statistical Threshold Value, STV) or (when n≥2) GM ≥ 126 CFU/100 mL. Caution is shown when latest is 235–409 CFU/100 mL and (if computed) GM < 126; otherwise Good.

Site	Waterbody	Date	E. coli (CFU/100 mL)	30-day GM	Status

“GM” = geometric mean of samples in the last 30 days for the site. Non-detects (“<”) are treated as half the detection limit; “>” are shown as reported.

Game: River Ranger — E. coli Invaders

Ready?

Click to play. Use ←/→ to move and hold Space to fire. Clear levels quickly for time bonuses.

▶

Score: 0

Lives: 3

Level: 1 / 5

About the game: A just-for-fun, Space-Invaders-style mini-game where each “invader” represents potential E. coli contamination. Use ←/→ to move and hold Space to fire. Clear levels quickly to earn time-based bonus points.

High Scores

#	Initials	Score	Date

About the Data & Health Guidance

What this dashboard shows: culture-based E. coli measurements (CFU/100 mL; MPN/100 mL for Quanti-Tray/Colilert methods) from EBCI rivers and streams to support safe recreation and public transparency.

Why E. coli? It is an indicator of fecal contamination. While most strains are harmless, elevated counts correlate with a higher probability of pathogens that can cause gastrointestinal illness.
How to interpret results (EPA Recreational Water Quality Criteria, 2012):
- Geometric Mean (GM): target ≤ 126 CFU/100 mL computed over a 30-day window (EPA recommends ≥5 samples where feasible).
- Statistical Threshold Value (STV): single-sample level 410 CFU/100 mL; no more than 10% of samples should exceed the STV over the same assessment window.
- EBCI status badges: Good (below GM & STV), Caution (235–409), Advisory (≥410 or GM ≥126).
When levels are high: After rainfall or runoff events, bacteria often spike for 24–48 hours. Consider postponing swimming/wading, avoid ingesting water, and wash hands before eating.
Higher-risk groups: young children, older adults, pregnant people, and those who are immunocompromised should take extra care.
Data limitations: Single samples are snapshots; conditions change rapidly with weather and flow. The GM smooths noise but requires multiple samples.

Official resources:

Cherokee Code, Chapter 113E – Water Quality: https://library.municode.com/tribes_and_tribal_nations/eastern_band_of_cherokee_indians/codes/code_of_ordinances?nodeId=THCHCO_CH113EWAQUCOTRWA
EPA Recreational Water Quality Criteria (2012): https://www.epa.gov/wqc/recreational-water-quality-criteria-and-methods
EPA E. coli parameter factsheet: https://www.epa.gov/system/files/documents/2021-07/parameter-factsheet_e.-coli.pdf