Water Quality
Water Quality > Tributary and Waterfront Data > Saw Mill River > New Castle- Tertia Brook tributary

New Castle- Tertia Brook tributary

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Physical/Chemical Data

Physical, chemical and biological properties of the surface water that are measured continuously while the patrol boat is underway.

Entero Count (fecal indicator) and Rainfall

94 Samples taken

Sample Date [i] Enterococcus Count
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Entero Count

Enterococcus (“Entero”) is a fecal indicating bacterium that lives in the intestines of humans and other warm-blooded animals. It is the EPA preferred indicator for sewage contamination.

Quality Rain, day of (in) Prior Day 2 Days Prior 3 Days Prior Rain 4 Days Total Rain
Sort Sort Sort Sort Sort Sort Sort Sort
09/05/2024 428 Beach Advisory 0.0 0.0 0.0 0.0 0.0
08/22/2024 364 Beach Advisory 0.0 0.0 0.4 2.9 3.3
08/08/2024 1470 Beach Advisory 0.1 2.1 0.0 0.5 2.7
07/25/2024 728 Beach Advisory 0.0 0.1 0.4 0.0 0.6
07/11/2024 683 Beach Advisory 0.0 0.0 0.0 0.0 0.0
06/27/2024 2589 Beach Advisory 0.9 0.0 0.0 0.0 0.9
06/13/2024 355 Beach Advisory 0.0 0.0 0.0 0.0 0.0
05/30/2024 3654 Beach Advisory 0.6 0.0 0.8 0.1 1.5
05/16/2024 1892 Beach Advisory 0.0 0.2 0.0 0.0 0.2
05/02/2024 206 Beach Advisory 0.0 0.1 0.0 0.0 0.1
10/19/2023 211 Beach Advisory 0.0 0.0 0.0 0.0 0.0
10/05/2023 228 Beach Advisory 0.0 0.0 0.0 0.0 0.0
09/21/2023 480 Beach Advisory 0.0 0.0 0.0 1.9 1.9
09/07/2023 393 Beach Advisory 0.0 0.0 0.0 0.0 0.0
08/24/2023 328 Beach Advisory 0.0 0.0 0.0 0.0 0.0
08/10/2023 836 Beach Advisory 0.0 0.0 0.0 1.7 1.7
07/27/2023 771 Beach Advisory 0.0 0.0 0.5 0.0 0.5
07/13/2023 388 Beach Advisory 0.0 0.0 0.0 0.8 0.8
06/29/2023 3076 Beach Advisory 0.0 0.0 0.1 1.0 1.1
06/15/2023 1585 Beach Advisory 0.0 0.6 0.0 0.1 0.7
06/01/2023 295 Beach Advisory 0.0 0.0 0.0 0.0 0.0
05/18/2023 146 Beach Advisory 0.0 0.0 0.0 0.0 0.0
05/04/2023 52 Acceptable 0.0 0.0 0.0 0.3 0.3
10/27/2022 213 Beach Advisory 0.0 0.0 0.1 0.3 0.4
10/13/2022 262 Beach Advisory 0.0 0.0 0.0 0.0 0.0
09/29/2022 428 Beach Advisory 0.0 0.0 0.0 0.0 0.0
09/15/2022 3654 Beach Advisory 0.0 0.0 0.6 0.2 0.8
09/01/2022 2603 Beach Advisory 0.0 0.0 0.1 0.0 0.1
08/18/2022 345 Beach Advisory 0.0 0.0 0.0 0.0 0.0
08/04/2022 299 Beach Advisory 0.0 0.0 0.0 0.4 0.4
07/21/2022 1296 Beach Advisory 0.0 0.0 0.0 2.3 2.4
10/21/2021 94 Beach Advisory 0.0 0.0 0.0 0.0 0.0
10/07/2021 275 Beach Advisory 0.0 0.0 0.0 0.5 0.6
09/23/2021 435 Beach Advisory 0.0 0.0 0.0 0.0 0.0
09/09/2021 2382 Beach Advisory 0.2 0.0 0.0 0.0 0.2
08/05/2021 282 Beach Advisory 0.0 0.0 0.0 0.0 0.0
07/22/2021 345 Beach Advisory 0.0 0.0 0.0 0.1 0.1
07/08/2021 2359 Beach Advisory 0.0 0.0 0.7 0.0 0.7
06/24/2021 171 Beach Advisory 0.0 0.0 0.0 0.0 0.0
06/10/2021 743 Beach Advisory 0.0 0.0 0.0 0.9 0.9
05/27/2021 576 Beach Advisory 0.1 0.0 0.0 0.0 0.1
05/13/2021 185 Beach Advisory 0.0 0.0 0.0 0.2 0.2
10/24/2019 85 Beach Advisory 0.0 0.0 0.2 0.0 0.2
10/10/2019 1274 Beach Advisory 0.0 0.0 0.1 0.2 0.3
09/26/2019 160 Beach Advisory 0.0 0.0 0.1 0.0 0.1
08/15/2019 388 Beach Advisory 0.0 0.0 0.0 0.0 0.0
08/01/2019 657 Beach Advisory 0.0 0.0 0.0 0.0 0.0
07/02/2019 958 Beach Advisory 0.0 0.0 0.0 0.0 0.0
06/20/2019 259 Beach Advisory 0.0 0.0 1.1 0.0 1.1
06/06/2019 565 Beach Advisory 0.0 0.0 0.0 0.0 0.0
05/23/2019 1296 Beach Advisory 0.1 0.0 0.0 0.2 0.3
05/09/2019 1067 Beach Advisory 0.0 0.0 0.1 0.0 0.1
10/18/2018 85 Beach Advisory 0.0 0.0 0.0 0.0 0.0
10/04/2018 450 Beach Advisory 0.0 0.0 2.4 0.0 2.4
09/20/2018 364 Beach Advisory 0.0 0.0 0.0 0.0 0.0
09/06/2018 7270 Beach Advisory 0.0 0.0 0.0 0.0 0.0
08/23/2018 959 Beach Advisory 0.0 1.0 0.0 0.0 1.0
08/09/2018 839 Beach Advisory 0.0 0.0 0.6 0.0 0.6
07/26/2018 488 Beach Advisory 0.0 1.0 0.0 0.6 1.6
07/12/2018 520 Beach Advisory 0.0 0.0 0.0 0.0 0.0
06/14/2018 1137 Beach Advisory 0.0 0.0 0.0 0.0 0.0
05/31/2018 663 Beach Advisory 0.0 0.0 0.0 0.0 0.0
05/17/2018 2909 Beach Advisory 0.2 1.0 0.4 0.0 1.6
10/26/2017 2495 Beach Advisory 0.0 0.0 0.4 0.0 0.4
10/12/2017 1254 Beach Advisory 0.1 0.0 0.0 0.2 0.3
09/28/2017 85 Beach Advisory 0.0 0.0 0.0 0.0 0.0
09/14/2017 31 Acceptable 0.0 0.0 0.0 0.0 0.0
08/31/2017 41 Acceptable 0.0 0.0 0.0 0.0 0.0
08/03/2017 933 Beach Advisory 0.0 1.0 0.0 0.0 1.0
07/20/2017 166 Beach Advisory 0.0 0.0 0.0 0.0 0.0
07/06/2017 441 Beach Advisory 0.0 0.0 0.0 0.0 0.0
06/22/2017 638 Beach Advisory 0.0 0.0 0.0 0.9 0.9
06/08/2017 75 Beach Advisory 0.0 0.0 0.2 0.1 0.3
05/25/2017 350 Beach Advisory 0.1 0.0 0.0 0.2 0.3
05/11/2017 98 Beach Advisory 0.0 0.0 0.0 0.0 0.0
10/27/2016 160 Beach Advisory 0.0 0.0 0.0 0.0 0.0
10/13/2016 310 Beach Advisory 0.0 0.0 0.0 0.0 0.0
09/29/2016 11200 Beach Advisory 0.0 0.0 0.4 0.0 0.4
09/15/2016 30 Acceptable 0.0 0.0 0.0 0.0 0.0
09/01/2016 280 Beach Advisory 0.0 0.0 0.0 0.0 0.0
08/18/2016 690 Beach Advisory 0.0 0.0 0.0 0.0 0.0
08/04/2016 180 Beach Advisory 0.0 0.0 0.0 0.0 0.0
07/14/2016 1550 Beach Advisory 0.0 0.0 0.0 0.0 0.0
06/30/2016 6130 Beach Advisory 0.0 0.0 0.3 0.3 0.6
06/16/2016 420 Beach Advisory 0.0 0.0 0.0 0.0 0.0
06/02/2016 420 Beach Advisory 0.0 0.0 0.0 0.6 0.6
05/19/2016 50 Acceptable 0.0 0.0 0.0 0.0 0.0
10/08/2015 464 Beach Advisory 0.0 0.0 0.0 0.0 0.0
09/24/2015 110 Beach Advisory 0.0 0.0 0.0 0.0 0.0
09/10/2015 8664 Beach Advisory 0.2 0.0 0.0 0.0 0.2
08/27/2015 638 Beach Advisory 0.0 0.0 0.0 0.0 0.0
08/13/2015 14136 Beach Advisory 0.0 0.0 0.6 0.0 0.6
07/30/2015 959 Beach Advisory 0.0 0.0 0.0 0.0 0.0
07/16/2015 3654 Beach Advisory 0.0 0.0 0.4 0.0 0.4

Entero Count (fecal indicator) and Rainfall Correlation

94 Samples taken

Water Quality*

Acceptable (0–60) Beach Advisory (61+)

*Single sample thresholds;
Enterococcus count per 100mL

Prior Four Day Rainfall
(in inches)

Dry Weather (0–0.25) Wet Weather (0.25+)

Enterococcus is an EPA-approved fecal contamination indicator.

Samples taken by citizen scientists and processed at laboratories that aren't directly affiliated with Riverkeeper, using methods and study designs that are consistent with Riverkeeper's Hudson River and Citizen Testing programs.

Rainfall data comes from wunderground.com. Wet weather is a common trigger of fecal contamination.

What do the Numbers Mean?

Water Quality scoring is based on the 2012 Recreational Water Quality Criteria from the US Environmental Protection Agency (EPA) for safe swimming. Learn More

About this location:

The Tertia Brook is the first named tributary to enter the Saw Mill River. This site is located where the Tertia Brook enters the parking lot of the Chappaqua Public Library. Upstream of here, the brook flows from its headwaters through residential areas.

Agencies Responsible:

Westchester County Dept. of Health: 914-813-5000; NYSDEC Region 3: 914-428-2505

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