to construct, improve, extend, or otherwise provide and maintain, by contract or otherwise, essential sanitation facilities, including domestic and community water supplies and facilities, drainage facilities, and sewage- and waste-disposal facilities, together with necessary appurtenances and fixtures, for Indian homes, communities, and lands;

to acquire lands, or rights or interests therein, including sites, rights-of-way, and easements, and to acquire rights to the use of water, by purchase, lease, gift, exchange, or otherwise, when necessary for the purposes of this section, except that no lands or rights or interests therein may be acquired from an Indian tribe, band, group, community, or individual other than by gift or for nominal consideration, if the facility for which such lands or rights or interests therein are acquired is for the exclusive benefit of such tribe, band, group, community, or individual, respectively;