We standardly recommend that residents of bluff-top property avoid adding to the groundwater near or on the face of the bluff, and therefore not aggravate instability. Tightlines need to be installed carefully and inspected frequently. If they fail, which they typically do in the wettest conditions, they may concentrate enormous flows in exactly the wrong place. Tightlines can be damaged by wind, falling tree limbs, and small slides. They can also be clogged by animal nests, ice, or debris.
Many landslides occur where tightlines and drain pipes fail.
They can also carry surface water that can contain oils, fertilizers, household chemicals, and other contaminants directly to the beach. Ask the Expert and FAQs, Project Impact, City of Seattle. Questions answered by the Federal Emergency Management Agency.