Technical Abstract: Technical Abstract: Accurate assessment of phytoplankton chlorophyll a concentration by remote sensing is challenging in turbid hyper-eutrophic waters. This paper assessed methods to improve this problem. A hand-held spectroradiometer was used to measure subsurface spectral reflectance (R) in the visible and near infra-red range of the spectrum. Water samples were collected concurrently and contained variable chlorophyll a (chl a from 107 to more than 3000 mg/m3) and turbidity (from 11 to 357 NTU) levels. The conceptual three-band model [R-1(lambda1)-R-1(lambda2)]lambdaR(lambda3) and its special case, the two-band model R(lambda3)/R(lambda1), were spectrally tuned in accord with optical properties of the media to optimize spectral bands (lambda1,lambda2, and lambda3) for accurate chl a estimation. Strong linear relationships were established between analytically measured chl a and both the three-band [R-1(650)-R-1(710)]xR(740) and the reflectance ratio model R(714)/(R650). The three-band model accounted for 7% more variation of chl a concentration than the ratio model (78 versus 71%). The findings underlined the rationale behind the conceptual model and demonstrated the robustness of the algorithm for chl a retrieval in very turbid, hyper-eutrophic waters.