How could the problem of algal blooms be solved?

Organic farming methods enable farmers and gardeners to prepare soil in such a way that nitrogen is added naturally through nitrogen-fixing bacteria rather than nitrogen having to be added through a synthetic fertilizer. This method of growing crops saves farmers money and alleviates the problems associated with fertilizer runoff
Farmers and gardeners should use other methods to provide crops with the nitrogen they need.

Algal blooms are due to the accumulation of algae, generally Cynabobacteria and Dinoflagellates, that grow due to excess nutrients in water.
If good algae grow, they do not accumulate in the waterbodies.

Diatom Algae are good algae.

Therefore if Diatoms are grown instead of Cyanobacteria and Dinoflagellates, there would be no accumulation and no problem of algal blooms.

Its either a) or b),wind and water erosion gradually widen the canyon