^a Key Laboratory of Environmental Aquatic Chemistry, State Key Laboratory of Regional Environment and Sustainability, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
^b School of Environment and Spatial Informatics, China University of Mining and Technology, Xuzhou 221116, China.
^c Management Station of Shuangxikou Reservoir, Reservoir Management Service Center of Yuyao, Ningbo 315423, China.
^d College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China.
^e University of Chinese Academy of Sciences, Beijing 100049, China.

^* Corresponding to: Ming Su (mingsu@rcees.ac.cn), Min Yang (yangmin@rcees.ac.cn)

Figures and/or tables are provided below as the supplementary evidences to the main text.

Comparative analysis of algal mitigation strategies

Method	Genera	Advantages	Disadvantages	Reference
Copper sulfate	Microcystis	Rapid efficacy	Copper ion residuals; Disrupts microbial diversity	(Liu et al., 2023)
Copper sulfate	Pseudokirchneriella	Easy operation	High resistance	(Tsai, 2016)
Solid sodium percarbonate	Pseudanabaena	Less impact on microbial diversity	Differentiated response	(Xu et al., 2021)
Ultrasound	Microcystis	No chemical additives; Disruption of gas vesicles	High energy demand; Ineffective against small algae	(Kong et al., 2019)
Ultrasound	Hydrodictyon	Fragments trichomes	Limited effectiveness	(Lee et al., 2014)
Aeration/mixing	Microcystis	Inhibition of surface aggregation	Limited effectiveness in emergency situation	(He et al., 2024)
Flocculation	Microcystis, Pseudanabaena	High efficiency	Aluminum residuals; Introduction of additional substances; Pre-treatment requirement	(Li and Pan, 2015; Xu et al., 2024)
Sediment Resuspension	Pseudanabaena	Spectral targeting; Eco-sustainability; Cost-effectiveness	Threshold limitation; Turbidity increase; Not applicable under sediment contamination	this study; (Fang et al., 2024; Su et al., 2025)

Table S1: Comparative analysis of algal mitigation strategies: Conventional versus SR-based approaches.

Seasonal distribution of filamentous cyanobacteria density range across 40 reservoirs

Distribution of nutrients concentration range across 40 reservoirs

Temporal dynamics and statistical distribution of underwater light intensity across experimental treatments

Fig. S3: **Temporal dynamics and statistical distribution of underwater light intensity (I_c(0.05m)) across experimental shading treatments.** a, High-resolution measurements of underwater light intensity (μmol m^-2 s^-1) at 0.05 m depth under graduated shading treatments (0 – 98% surface coverage), recorded at 15-min intervals (09:00 – 16:00) during Day 1 of sediment resuspension (SR) deployment. b, Boxplot analysis of light regimes by treatment, showing statistically distinct reductions in I_c(0.05m) relative to unshaded controls.

Temporal dynamics of dissolved nitrogen concentration across experimental treatments

Seasonal variations in mixed layer depth across 40 drinking water reservoirs

Fig. S5: **Seasonal variations in mixed layer depth (z_mix) across 40 drinking water reservoirs**.

Seasonal variations in underwater light available across 40 drinking water reservoirs

Fig. S6: **Seasonal variations in underwater light available (I_dc) across 40 drinking water reservoirs.**

Seasonal variations in water temperature across 40 drinking water reservoirs

Fig. S7: **Seasonal variations in water temperature (T) across 40 drinking water reservoirs.**

Seasonal dynamics of predicted filamentous cyanobacteria density and environmental drivers across 40 reservoirs

Monthly distribution of predicted filamentous cyanobacteria density risk range across 40 reservoirs

Seasonal control rates of filamentous cyanobacteria bloom mitigation across 40 reservoirs

Fig. S10: **Seasonal control rates (CR) of filamentous cyanobacteria bloom mitigation across 40 reservoirs.** Monthly success rates for reducing predicted filamentous cyanobacteria densities from initial bloom conditions to target Risk Level 2 (\(RL_2\): 2 × 10⁷ cells L^-1) within 10 days.

Monthly effectiveness of sediment resuspension for controlling filamentous cyanobacteria blooms across 40 reservoirs

Temporal dynamics of underwater light available across bloom stage in S Reservoir

Fig. S12: **Temporal dynamics of underwater light available (I_dc) across bloom stage in S Reservoir.**

Workflow for determining the optimal sediment resuspension (SR) operating conditions

Dynamics of nutrients concentration before and during SR in S Reservoir

Fig. S14: **Dynamics of dissolved ammonia nitrogen and dissolved phosphorus before and during SR in S Reservoir**

Field applications in five drinking water reservoirs

Fig. S15: ‎ **The comparison of observed total phytoplankton cell densities between sites with Sediment Resuspension (SR) operations (FE) and those without (FC) was conducted across five drinking water reservoirs.** Long‐term SR technology was implemented in SMH and SXK Reservoirs to evaluate its effectiveness in preventing cyanobacterial growth (A), while the CX, NJ, and HM Reservoirs underwent short‐term evaluation for cyanobacterial bloom control (B). Panel C illustrates the comparison of Oxidation‐Reduction Potential (ORP) of reservoir sediment and total phosphorus concentration of reservoir water, assessing the effect of long‐term SR on sediment and water quality. Furthermore, panel D depicts the relationship between cell removal rate and SR working intensity, accompanied by several images that document the changes in the water surface of the CX Reservoir following SR operations from day 0 to day 10. Notably, a severe *Microcystis* bloom in the CX Reservoir provided a vivid visual representation of the changes in the water bodies.

Optimal SR flux for control of filamentous cyanobacterial blooms under various meteorological conditions, bloom intensities and mixed layer

Fig. S16: Optimal SR flux for control of filamentous cyanobacterial blooms under various meteorological conditions (daily surface light intensity, I₀, 0 - 20 mol m^-2 d^-1), bloom intensities (0.8 - 2.8 × 10⁸ cells L^-1) and mixed layer depths (8 - 28 m).

Sketch of weather-based implementation of underwater light regulation

Light modulation efficacy for controlling filamentous cyanobacteria blooms with z_mix of 6 m under varying solar regimes

No. 1 Light modulation efficacy under initial predicted density of 80 M under z_mix of 6 m

Fig. S18: **Light modulation efficacy under initial predicted density of 80 M under z_mix of 6 m.** Dynamics of underwater irradiance (\(I_{\text{0}}\), 2 - 20 μmol m^-2 d^-1 etc,.) across sediment resuspension (SR) conditions (x-axis: sediment concentration 0.1 - 8.0 g L^-1; color: resuspension frequency 1 - 5 cycles d^-1), faceted by incident solar radiation quartiles. Horizontal dashed lines indicate critical light thresholds required to suppress blooms from initial predicted density of 0.8 × 10⁸ cells L^-1 to Risk Level 2 (\(RL_{\text{2}}\): 2 × 10⁷ cells L^-1) within N (N = 10) days. Brown points denote optimal SR parameters balancing algal control and operational cost (minimal sediment loading).

No. 2 Light modulation efficacy under initial predicted density of 120 M under z_mix of 6 m

Fig. S19: **Light modulation efficacy under initial predicted density of 120 M under z_mix of 6 m**. Dynamics of underwater irradiance (\(I_{\text{0}}\), 2 - 20 μmol m^-2 d^-1 etc,.) across sediment resuspension (SR) conditions (x-axis: sediment concentration 0.1 - 8.0 g L^-1; color: resuspension frequency 1 - 5 cycles d^-1), faceted by incident solar radiation quartiles. Horizontal dashed lines indicate critical light thresholds required to suppress blooms from initial predicted density of 1.2 × 10⁸ cells L^-1 to Risk Level 2 (\(RL_{\text{2}}\): 2 × 10⁷ cells L^-1) within N (N = 10) days. Brown points denote optimal SR parameters balancing algal control and operational cost (minimal sediment loading).

No. 3 Light modulation efficacy under initial predicted density of 160 M under z_mix of 6 m

Fig. S20: **Light modulation efficacy under initial predicted density of 160 M under z_mix of 6 m.** Dynamics of underwater irradiance (\(I_{\text{0}}\), 2 - 20 μmol m^-2 d^-1 etc,.) across sediment resuspension (SR) conditions (x-axis: sediment concentration 0.1 - 8.0 g L^-1; color: resuspension frequency 1 - 5 cycles d^-1), faceted by incident solar radiation quartiles. Horizontal dashed lines indicate critical light thresholds required to suppress blooms from initial predicted density of 1.6 × 10⁸ cells L^-1 to Risk Level 2 (\(RL_{\text{2}}\): 2 × 10⁷ cells L^-1) within N (N = 10) days. Brown points denote optimal SR parameters balancing algal control and operational cost (minimal sediment loading).

No. 4 Light modulation efficacy under initial predicted density of 200 M under z_mix of 6 m

Fig. S21: **Light modulation efficacy under initial predicted density of 200 M under z_mix of 6 m.** Dynamics of underwater irradiance (\(I_{\text{0}}\), 2 - 20 μmol m^-2 d^-1 etc,.) across sediment resuspension (SR) conditions (x-axis: sediment concentration 0.1 - 8.0 g L^-1; color: resuspension frequency 1 - 5 cycles d^-1), faceted by incident solar radiation quartiles. Horizontal dashed lines indicate critical light thresholds required to suppress blooms from initial predicted density of 2.0 × 10⁸ cells L^-1 to Risk Level 2 (\(RL_{\text{2}}\): 2 × 10⁷ cells L^-1) within N (N = 10) days. Brown points denote optimal SR parameters balancing algal control and operational cost (minimal sediment loading).

No. 5 Light modulation efficacy under initial predicted density of 240 M under z_mix of 6 m

Fig. S22: **Light modulation efficacy under initial predicted density of 240 M under z_mix of 6 m.** Dynamics of underwater irradiance (\(I_{\text{0}}\), 2 - 20 μmol m^-2 d^-1 etc,.) across sediment resuspension (SR) conditions (x-axis: sediment concentration 0.1 - 8.0 g L^-1; color: resuspension frequency 1 - 5 cycles d^-1), faceted by incident solar radiation quartiles. Horizontal dashed lines indicate critical light thresholds required to suppress blooms from initial predicted density of 2.4 × 10⁸ cells L^-1 to Risk Level 2 (\(RL_{\text{2}}\): 2 × 10⁷ cells L^-1) within N (N = 10) days. Brown points denote optimal SR parameters balancing algal control and operational cost (minimal sediment loading).

No. 6 Light modulation efficacy under initial predicted density of 280 M under z_mix of 6 m

Fig. S23: **Light modulation efficacy under initial predicted density of 280 M under z_mix of 6 m.** Dynamics of underwater irradiance (\(I_{\text{0}}\), 2 - 20 μmol m^-2 d^-1 etc,.) across sediment resuspension (SR) conditions (x-axis: sediment concentration 0.1 - 8.0 g L^-1; color: resuspension frequency 1 - 5 cycles d^-1), faceted by incident solar radiation quartiles. Horizontal dashed lines indicate critical light thresholds required to suppress blooms from initial predicted density of 2.8 × 10⁸ cells L^-1 to Risk Level 2 (\(RL_{\text{2}}\): 2 × 10⁷ cells L^-1) within N (N = 10) days. Brown points denote optimal SR parameters balancing algal control and operational cost (minimal sediment loading).

Observed variations in Pseudanabaena abundance across different light conditions

Fig. S24: ‎ **A rainfall event reveals how ambient light regulates shading efficacy against filamentous cyanobacteria (*Pseudanabaena*)** Differential impacts of identical shading treatments (L1–L5) on *Pseudanabaena* biomass during high-light pre-rain (S1) and low-light post-rain (S3) periods.

Growth responses of Microcystis* and filamentous cyanobacteria to light intensity

Optimal sediment resuspension strategies for filamentous cyanobacteria control across seasonal 40 reservoir systems

No. 1 BX Reservoir

Fig. S26: Underwater light availability (y-axis) under varying sediment resuspension conditions (x-axis: sediment concentration, \(c_{\text{sed}}\); color: resuspension frequency, \(n\)) in BX reservoir (March - October). Horizontal dashed lines indicate month-specific critical light thresholds (\(I_{\text{dc}}\)) required to suppress algal biomass to Risk Level 2 (\(RL_{\text{2}}\): 2 × 10⁷ cells L^-1) within N (N = 10) days. Conditions where resuspension-induced light attenuation falls below thresholds (points beneath dashed lines) represent effective algal control scenarios (green aera). Brown points identify optimal operational conditions - meeting critical light requirements while minimizing resuspension frequency, thereby balancing ecological efficacy with operational sustainability. Shaded regions highlight 95% confidence intervals for threshold responses.

No. 2 CAG Reservoir

Fig. S27: **Underwater light availability under varying sediment resuspension conditions in CAG reservoir (March - October).**

No. 3 CT Reservoir

Fig. S28: **Underwater light availability under varying sediment resuspension conditions in CT reservoir (March - October).**

No. 4 DH Reservoir

Fig. S29: **Underwater light availability under varying sediment resuspension conditions in DH reservoir (March - October).**

No. 5 DHK Reservoir

Fig. S30: **Underwater light availability under varying sediment resuspension conditions in DHK reservoir (March - October).**

No. 6 DTG Reservoir

Fig. S31: **Underwater light availability under varying sediment resuspension conditions in DTG reservoir (March - October).**

No. 7 EJL Reservoir

Fig. S32: **Underwater light availability under varying sediment resuspension conditions in EJL reservoir (March - October).**

No. 8 FH Reservoir

Fig. S33: **Underwater light availability under varying sediment resuspension conditions in FH reservoir (March - October).**

No. 9 FS Reservoir

Fig. S34: **Underwater light availability under varying sediment resuspension conditions in FS reservoir (March - October).**

No. 10 GXZ Reservoir

Fig. S35: **Underwater light availability under varying sediment resuspension conditions in GXZ reservoir (March - October).**

No. 11 HCG Reservoir

Fig. S36: **Underwater light availability under varying sediment resuspension conditions in HCG reservoir (March - October).**

No. 12 HJ Reservoir

Fig. S37: **Underwater light availability under varying sediment resuspension conditions in HJ reservoir (March - October).**

No. 13 HK Reservoir

Fig. S38: **Underwater light availability under varying sediment resuspension conditions in HK reservoir (March - October).**

No. 14 HM Reservoir

Fig. S39: **Underwater light availability under varying sediment resuspension conditions in HM reservoir (March - October).**

No. 15 HP Reservoir

Fig. S40: **Underwater light availability under varying sediment resuspension conditions in HP reservoir (March - October).**

No. 16 HS Reservoir

Fig. S41: **Underwater light availability under varying sediment resuspension conditions in HS reservoir (March - October).**

No. 17 HX Reservoir

Fig. S42: **Underwater light availability under varying sediment resuspension conditions in HX reservoir (March - October).**

No. 18 HXH Reservoir

Fig. S43: **Underwater light availability under varying sediment resuspension conditions in HXH reservoir (March - October).**

No. 19 LH Reservoir

Fig. S44: **Underwater light availability under varying sediment resuspension conditions in LH reservoir (March - October).**

No. 20 LHT Reservoir

Fig. S45: **Underwater light availability under varying sediment resuspension conditions in LHT reservoir (March - October).**

No. 21 LSK Reservoir

Fig. S46: **Underwater light availability under varying sediment resuspension conditions in LSK reservoir (March - October).**

No. 22 LY Reservoir

Fig. S47: **Underwater light availability under varying sediment resuspension conditions in LY reservoir (March - October).**

No. 23 MH Reservoir

Fig. S48: **Underwater light availability under varying sediment resuspension conditions in MH reservoir (March - October).**

No. 24 MX Reservoir

Fig. S49: **Underwater light availability under varying sediment resuspension conditions in MX reservoir (March - October).**

No. 25 NJ Reservoir

Fig. S50: **Underwater light availability under varying sediment resuspension conditions in NJ reservoir (March - October).**

No. 26 SA Reservoir

Fig. S51: **Underwater light availability under varying sediment resuspension conditions in SA reservoir (March - October).**

No. 27 SLH Reservoir

Fig. S52: **Underwater light availability under varying sediment resuspension conditions in SLH reservoir (March - October).**

No. 28 SLK Reservoir

Fig. S53: **Underwater light availability under varying sediment resuspension conditions in SLK reservoir (March - October).**

No. 29 SMH Reservoir

Fig. S54: **Underwater light availability under varying sediment resuspension conditions in SMH reservoir (March - October).**

No. 30 SXK Reservoir

Fig. S55: **Underwater light availability under varying sediment resuspension conditions in SXK reservoir (March - October).**

No. 31 SXP Reservoir

Fig. S56: **Underwater light availability under varying sediment resuspension conditions in SXP reservoir (March - October).**

No. 32 SZ Reservoir

Fig. S57: **Underwater light availability under varying sediment resuspension conditions in SZ reservoir (March - October).**

No. 33 TX Reservoir

Fig. S58: **Underwater light availability under varying sediment resuspension conditions in TX reservoir (March - October).**

No. 34 TZG Reservoir

Fig. S59: **Underwater light availability under varying sediment resuspension conditions in TZG reservoir (March - October).**

No. 35 XK Reservoir

Fig. S60: **Underwater light availability under varying sediment resuspension conditions in XK reservoir (March - October).**

No. 36 XLA Reservoir

Fig. S61: **Underwater light availability under varying sediment resuspension conditions in XLA reservoir (March - October).**

No. 37 XXN Reservoir

Fig. S62: **Underwater light availability under varying sediment resuspension conditions in XXN reservoir (March - October).**

No. 38 YML Reservoir

Fig. S63: **Underwater light availability under varying sediment resuspension conditions in YML reservoir (March - October).**

No. 39 ZGZ Reservoir

Fig. S64: **Underwater light availability under varying sediment resuspension conditions in ZGZ reservoir (March - October).**

No. 40 ZX Reservoir

Fig. S65: **Underwater light availability under varying sediment resuspension conditions in ZX reservoir (March - October).**

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