Shandaken Tunnel Outflow Turbidity and Temperature

Posted on: September 12th, 2013 by Leslie_Zucker

You may have noticed over recent weeks that Shan­dak­en Tun­nel out­flows into the Eso­pus Creek have sus­tained high­er tur­bid­i­ty lev­els than would nor­mal­ly be observed dur­ing dry sum­mer con­di­tions. Accord­ing to NYC Depart­ment of Envi­ron­men­tal Pro­tec­tion (DEP) offi­cials, tur­bid­i­ty lev­els mea­sured at the Schoharie intake have var­ied from 20–50 NTU in recent weeks, with tem­po­rary spikes up to dou­ble that amount dur­ing brief peri­ods. As a result, the DEP has been oper­at­ing the Tun­nel at a reduced min­i­mum flow of 97 MGD, with per­mis­sion from the NYS Depart­ment of Envi­ron­men­tal Con­ser­va­tion. DEP offi­cials say the cause of ele­vat­ed tur­bid­i­ty lev­els is cur­rent­ly unknown and they are inves­ti­gat­ing mul­ti­ple pos­si­ble caus­es. Tur­bid­i­ty lev­els are the same at the intake and out­flow of the Tun­nel, so inves­ti­ga­tions are focused on the Schoharie Reser­voir and water­shed. DEP has added addi­tion­al mon­i­tor­ing buoys to track con­di­tions in the Schoharie Reser­voir, sent divers into the reser­voir to ensure it was not the effect of fish activ­i­ty, and per­formed an aer­i­al inspec­tion that found no vis­i­ble prob­lems from upstream trib­u­taries. Also, DEP has ini­ti­at­ed addi­tion­al mod­el­ing to find and under­stand the root cause of the tur­bid­i­ty swings. At the same time, Tun­nel releas­es have had a pos­i­tive effect on water tem­per­a­ture in Eso­pus Creek. Until ear­ly August, day­time water tem­per­a­tures at Cold­brook remained below the 72 degrees F need­ed to sup­port trout populations.