Cal. Health & Safety Code § 4730.68

(a) This section applies only to county sanitation district numbers 1, 2, 3, 4, 5, 8, 9, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 27, 28, 29, and 34 of Los Angeles County, Newhall Ranch Sanitation District of Los Angeles County, South Bay Cities Sanitation District of Los Angeles County, and Santa Clarita Valley Sanitation District of Los Angeles County. The powers granted in this section supplement the existing powers of each district.
(b) A district may acquire, construct, operate, maintain, and furnish facilities for any of the following purposes:
1. (1) The diversion of stormwater and dry weather runoff from the stormwater drainage system within the district.
2. (2) The management and treatment of the stormwater and dry weather runoff.
3. (3) The discharge of the water to the stormwater drainage system or receiving waters.
4. (4) The beneficial use of the water.
(c) In order to carry out the powers and purposes granted under this section, the district may exercise any of the powers otherwise granted to a district by this chapter to the extent those powers may be made applicable.
(d)
1. (1) Prior to initiating a stormwater or dry weather runoff program or project within the boundaries of an adjudicated groundwater basin, a district shall consult with the relevant watermaster for a preliminary determination as to whether the project is inconsistent with the adjudication. If the watermaster deems the project to be inconsistent with the adjudication, the watermaster shall recommend, in writing, the measures that are necessary in order to conform the project to the adjudication.
2. (2) Prior to initiating a stormwater or dry weather runoff project within the service area of a water replenishment district, a district shall consult with the water replenishment district for the purpose of avoiding potential conflicts with water replenishment activities.
3. (3) Prior to initiating a stormwater or dry weather runoff project, a district shall consult with the Los Angeles County Flood Control District for the purpose of avoiding potential conflicts with flood protection and water conservation activities.
(e) This section does not affect any obligation of a district to obtain a permit that may be required by law for the activities undertaken pursuant to this section.
(f) For purposes of this section, “stormwater” and “dry weather runoff” have the same meaning as in Section 10561.5 of the Water Code.
(g) Nothing in this section shall be construed to require any local agency to participate, financially or otherwise, in a project pursued under the authority granted by this section.
(h) Nothing in this section shall be construed to alter or interfere with any of the following:
1. (1) Existing water rights to water from any source, including any adjudicated rights allocated by a court judgment or order, including any physical solution, rights issued by the state or a state agency, and rights acquired pursuant to any federal or state statute.
2. (2) Existing water rights law.
3. (3) Any rights, remedies, or obligations that may exist pursuant to Article 1 (commencing with Section 1200) or Article 1.5 (commencing with Section 1210) of Chapter 1 of Part 2 of Division 2 of the Water Code, Chapter 10 (commencing with Section 1700) of Part 2 of Division 2 of the Water Code, or Chapter 8.5 (commencing with Section 1501) of Part 1 of Division 1 of the Public Utilities Code.