Page 477 - northlakehills_deir_0517

NorthLake Specific Plan
Draft Supplemental EIR

5.8.4 RELEVANT REGULATIONS, PLANS, AND POLICIES

Federal

Clean Water Act

In 1972, the Federal Water Pollution Control Act [later referred to as the Clean Water Act (CWA)]
was amended to prohibit discharges of pollutants to waters of the United States from any point
source, unless the discharge is in compliance with a National Pollutant Discharge Elimination
System (NPDES) permit. In 1987, the CWA was amended to require that the USEPA establish
regulations for permitting of storm water discharges (as a point source) by municipal facilities,
industrial facilities, and construction activities under the NPDES permit program. The USEPA
published final regulations regarding stormwater discharges on November 16, 1990.The
regulations require that municipal separate storm sewer system (MS4) discharges to surface
waters must be regulated by an NPDES permit.

The CWA also requires states to adopt water quality standards for receiving water bodies that
have designated beneficial uses (e.g., municipal, agricultural supply, recreational), along with
water quality criteria necessary to support those uses. Water quality criteria are set concentrations
of pollutants (e.g., suspended sediment, chloride, heavy metals) or narrative statements that
represent the quality of water that is necessary to support a beneficial use. If the designated
beneficial uses of a water body are compromised by pollutants, Section 303(d) of the Clean Water
Act requires that the water body be listed as “impaired.” Because California did not establish a
complete list of acceptable water quality criteria, U.S. EPA established, in the California Toxics
Rule (CTR), numeric water quality criteria for certain toxic constituents in receiving waters with
human health or aquatic life designated uses (40 CFR 131.38).Once a water body has been
deemed impaired, a Total Maximum Daily Load (TMDL) must be developed for each water quality
pollutant that is causing the impairment.

CWA Section 303(d) – TMDLs

When designated beneficial uses of a particular receiving water body are being compromised by
water quality, Section 303(d) of the CWA requires identifying and listing that water body as
“impaired”. Once a water body has been deemed impaired, a TMDL must be developed for the
impairing pollutant(s). A TMDL is an estimate of the total load of pollutants from point, non-point,
and natural sources that a water body may receive without exceeding applicable water quality
standards (with a “factor of safety” included). Once established, the TMDL allocates the loads
among current and future pollutant sources to the water body.

The Project would discharge runoff through Grasshopper Creek, Castaic Lagoon, and Castaic
Creek to Santa Clara River Reach 5. Grasshopper Creek, Castaic Lagoon, and Castaic Creek
are no listed as impaired. Table 5.8-7, 2010 CWA Section 303(d) Listings for the Santa Clara
River Mainstem, lists the water quality impairments for the Santa Clara River, including reaches
upstream of the confluence of Castaic Creek and the Santa Clara River (although these upstream
impairments do not affect the Project), as reported in the 2010 CWA Section 303(d) List of Water
Quality Limited Segments. Reach 7 of the Santa Clara River (Bouquet Canyon Road to above
Lang Gaging Station) is listed for coliform bacteria. Reach 6 (West Pier Highway 99 to Bouquet
Canyon Road) is listed for chloride, coliform bacteria, chlorpyrifos, diazinon, toxicity, iron, and
copper. Reach 5 of the Santa Clara River (where the confluence of Castaic Creek with the Santa
Clara River is located) is listed for chloride, coliform bacteria, and iron. Santa Clara River Reach 3,
approximately 25 miles downstream of Reach 5 and below the Dry Gap in Reach 4, is listed for
ammonia, chloride, total dissolved solids (TDS), and toxicity. Santa Clara River Reach 1,
approximately 30 miles downstream of Reach 5, is listed for toxicity. The Santa Clara River

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