The consistency of the materials and construction techniques within each period leads to a certain consistency in the elements of deterioration. Earthworks are in generally good condition with isolated erosion and soil instability. Seismic activity and erosion have undermined some smaller concrete structures at Battery Townsley and Battery Crosby. Battery Mendell was placed on an eroding sand hillside and has developed serious structural problems. Other batteries including Battery Boutelle exhibit major cracking.
Trails often contribute to erosion.
At most batteries, soil migration and washing have affected surface drainage by obstructing positive drainage away from structures and filling surface and subsurface drainage systems. Vegetation Fortification sites were greatly disturbed during initial construction. Natural topographic profiles were altered and vegetation was planted to reduce erosion and provide natural camouflage. Existing vegetation is not fully original to the sites. Vegetation has overgrown most of the sites to the extent that it has obscured character-defining features.