(a) Upon request of the Governor of a State, or the appropriate official of local government, the Secretary is authorized to provide designs, plans, and specifications, and such other technical assistance as he deems advisable to such State or local government for its use in carrying out—

(1) projects for removing accumulated snags and other debris, and clearing and straightening channels in navigable streams and tributaries thereof; and

(2) projects for renovating navigable streams and tributaries thereof by means of predominantly nonstructural methods judged by the Secretary to be cost effective, for the purpose of improved drainage, water quality, and habitat diversity.

(b) The non-Federal share of the cost of any designs, plans, specifications or technical assistance provided under subsection (a) shall be 50 percent.