The impairment will be considered for delisting when:

The average DELT values within the assessment unit do not exceed either:

• DELT values of 3% (lacustuary and boat sites), or
• DELT values 1.3% (wading sites);

AND

Where brown bullheads are present, the liver tumor prevalence rate (i.e., neoplastic or preneoplastic liver tumors) should not exceed 5%.

Notes:

Two studies are currently underway to determine the background rates for tumor and deformity incidence rates in Ohio AOCs. Once the studies are complete, Ohio EPA will review the results and determine if the current target should be revised.

Brown bullhead liver tumor prevalence rates are evaluated in specified stream reaches within the AOC where populations are likely to be present.

Ohio EPA has identified the lacustuary zones of the following streams and reaches in the Cuyahoga River AOC for the evaluation of brown bullhead liver tumor incidence rates:
i. Mainstem/Marina
ii. Old Channel
iii. Euclid Creek