Water quality flags, with forecasted E.coli concentrations and probabilities (updated hourly):
As of: 02/23/18 10:59 Modeled Concentration Probability of Exceedance Flag
Model Reach 2
   Newton Yacht Club - cfu0% Blue (safe for boating)
   Watertown Yacht Club - cfu0% Blue (safe for boating)
   Community Rowing, Inc. - cfu0% Blue (safe for boating)
   CRCK at Herter Park - cfu0% Blue (safe for boating)
Model Reach 3
   Harvard's Weld Boathouse - cfu1% Blue (safe for boating)
Model Reach 4
   Riverside Boat Club - cfu0% Blue (safe for boating)
Model Reach 5
   Charles River Yacht Club- cfu-% Red (health risk)
   Union Boat Club- cfu-% Red (health risk)
   Community Boating- cfu-% Red (health risk)
   CRCK at Kendall Square- cfu-% Red (health risk)






Model formulas:

Reach 2 logistic model

ln(p/(1-p)) = 0.26 + 0.044*WtmpD1 - 0.036*AtmpD1 + 0.0014*Hours - 0.23*log(Hours+0.0001)

p = probability of exceeding safety threshold;

WtmpD1 = Previous 24hr average water temp (F); AtmpD1 = previous 24hr average air temp (F); Hours = Hours since last rain


Reach 3 logistic model

ln(p/(1-p)) = 1.41 + 0.026*WtmpD1 - 0.0007*PARD2 + 0.0009*Hours - 0.302*log(Hours+0.0001) + 0.0015*FlowD2 - log(FlowD2)

p = probability of exceeding safety threshold;

WtmpD1 = Previous 24hr average water temp (F); PARD2 = previous 48hr average PAR; Hours = Hours since last rain; FlowD2 = previous 48hr average flow


Reach 4 logistic model

ln(p/(1-p)) = 3.65 + 0.025*WtmpD1 - 0.664*PARD2 + 0.0014*Hours - 0.343*log(Hours+0.0001)

p = probability of exceeding safety threshold;

WtmpD1 = Previous 24hr average water temp (F); PARD2 = previous 48hr average PAR; Hours = Hours since last rain


Reach 5 logistic model

ln(p/(1-p)) = -3.18 + 3.94*RainD2 - 1.62*RainD7 + 1.28*log(FlowD1) - 0.34*WindD1 - 0.21*WtmpD1

p = probability of exceeding safety threshold;

RainD2 = Previous 48hr total rainfall; RainD7 = previous 7-day total rainfall

FlowD1 = Previous 24hr average riverflow; WindD1 = previous 24hr average windspeed

WtmpD1 = previous 24hr average water temp