Our first CWMN (Citizen Water Monitoring Network) mission of the season was a great success! Thanks, as always, to all of the dedicated volunteers who sacrifice their mornings to help us take water samples all over the Neponset.

The results have come back from the MWRA lab, and for the most part, they look good. Only 7 of the 41 sites had E. coli levels that are considered too high to be safe for swimming (anything over 235 cfus) . Of these 7 sites, 3 had levels low enough that made them considered safe for boating (anything under 630 cfus). We’ll see if the 4 worst sites have high E. coli again in the June data.

Map visualization of the E. coli data from the CWMN sites. Red sites have E. coli levels that exceed what’s considered safe for swimming, yellow sites have E. coli levels that exceed standards for boating but not swimming, and green sites are safe for both activities.

The 7 CWMN sites with the highest E. coli in May 2018.

None of the sites with high E. coli values were particularly surprising to us. We’ve seen high levels of bacteria in all of the sites in the past. Unquity Brook and Pine Tree Brook in Milton are both current subjects of our Hotspot program, where we go out and follow up on results from the CWMN data. We hope that we can uncover the cause of the high levels of E. coli so we can work with towns to address and fix the problem.

Carrying out a hotspot investigation in Pine Tree Brook.

If you’re curious about past CWMN results, check out our interactive map here.

If you’d like to be a part of this volunteer team, email me at o’connell@neponset.org!

Annie O’Connell, Environmental Science Fellow, June 2018