Section 21(3)(a) in Uttarakhand River Valley (Development and Management) Act, 2005
(a)for the purpose of this section the major developmental or constructional activity means the activity requiring excavation of soil upto the depth of three feet or more in an area comprised in the Master Plan or Sectoral Plan and having an plinth area of more then seventy five square metes in a double storey. Provided no such permission or NOC is required for the following activities -(i)Temporary structure and thatched house to be used as cattle-shed; or(ii)establishment of small water mills; or(iii)extension of existing house subject to the condition mentioned in sub section (2) of section 21 and its explanation; or(iv)construction of retaining walls or boundary walls used for the protection of existing house or agricultural fields or for maintenance of Roads and Pathways; or(v)emergency construction raised after having natural calamites and disasters in the area :