Berbagai aktivitas penyumbang pencemaran perairan yang dilakukan di daerah pesisir seperti rumah tangga, industri dan pelabuhan. limbah merupakan faktor yang mempengaruhi keberadaan bakteri e.coli dan total coliform dalam perairan. tujuan penelitian untuk mengukur kandungan e.coli dan total coliform perairan laut sehingga dapat memberikan gambaran tentang tingkat kebersihan atau pencemaran air laut di tempat yang diteliti. penelitian dilakukan menggunakan metode deskriptif, metode uji laboratorium yang digunakan yaitu colilert 18 (in house) dan sni 2333.1:2015, kemudian dibandingkan dengan peraturan pemerintah no.22 tahun 2021 mengenai baku mutu air laut air laut untuk pelabuhan, wisata bahari dan biota laut. titik pengukuran dan pengambilan sampel air laut dilakukan pada 5 titik stasiun dengan masing-masing stasiun 3 kali ulangan. hasil penelitian diperoleh nilai rata-rata e.coli pada stasiun 1-5 secara berurutan yaitu 16,3; 20,3; 12,7; 17,7; 23,7 jml/100 ml dan nilai rata-rata hasil pengukuran coliform 59.000,0; 1.673,3; 3.340,0; 1.386,7; 7.946,7 jml/100 ml. perairan pada stasiun 1-5 e.coli belum memenuhi standar baku yang ditetapkan untuk pelabuhan dan biota laut tetapi masih memenuhi standar untuk wisata bahari. total coliform disetiap stasiun belum memenuhi baku mutu yang telah ditetapkan untuk kegiatan pelabuhan, wisata bahari dan biota laut. kata kunci: angka paling mungkin (apm), baku mutu, laut dan pesisir, pencemaran

Various activities that contribute to water pollution are carried out in coastal areas such as households, industry, and ports. waste is a factor that affects the presence of e.coli and total coliform bacteria in waters. the objective of this study was to measure the contents of e.coli and total coliform in the marine waters of tarakan island. the study was conducted from april to june 2022 using a descriptive method. determination of the sampling locations was chosen by using a purposive sampling technique. laboratory analyses employed the colilert 18 (in house) method and sni 2333.1: 2015 standard. the findings were benchmarked against government regulation no.22 of 2021 concerning seawater quality standards for ports, marine tourism, and marine biota. measurement points and seawater sampling were carried out at 5 stations with 3 repetitions of each station based on the sources of pollution generation from activities in the sea and coastal areas. the results of the study obtained the average value of e.coli at stations 1-5 respectively were 16.3; 20.3; 12.7; 17.7; 23.7 mpn/100 ml and the average value of coliform measurement results 59,000.0; 1,673.3; 3,340.0; 1,386.7; 7,946.7 mpn/100 ml the results of measuring water quality parameters as supporting data obtained temperatures ranging from 30.7-31.3 °c, ph 7.3-8.0, do 2.6-4.9 mg/l, salinity 10.3-25.0 %, and tds 14.537-30.688 mg/l. the waters at stations 1-5 with escherichia coli parameters did not conform to the established standards for ports and marine biota. however, it did comply with the criteria designated for marine tourism. additionally, the total coliform levels at these stations failed to meet the stipulated quality benchmarks for port operations, marine tourism, and marine biota standards. keywords: most probable number (mpn), quality standards, marine and coastal, pollution