Biostimulatory Substances Objective and Program to Implement Biological Integrity
The Biological Integrity Assessment Implementation Plan will now be combined with the Biostimulatory Substances Amendment.
The State Water Resources Control Board (State Water Board) is proposing to adopt a statewide water quality objective for biostimulatory substances along with a program of implementation as an amendment (Biostimulatory Substances Amendment or project) to the Water Quality Control Plan for Inland Surface Water, Enclosed Bays and Estuaries of California (ISWEBE Plan). The Biostimulatory Substances Amendment could include: a statewide numeric objective or a statewide narrative objective (with a numeric translator), and various regulatory control options for point and non-point sources.
It is anticipated that a comprehensive program to implement the water quality objective for biostimulatory substances will be established in three phases as three amendments to the ISWEBE Plan. Each phase would reflect implementation unique to three different water body types. If the Biostimulatory Substances Amendment establishes a numeric water quality objective, rather than a narrative water quality objective, then potentially each subsequent phase would also establish a new numeric water quality objective. The latter depends on whether the numeric water quality objective is developed from factors unique to the different types of waterbodies. The Biostimulatory Amendment would be the first phase, applicable to wadeable streams. The second phase will focus on lakes and the third phase will focus on estuaries, enclosed bays, and non-wadeable rivers.
This project will also now include a water quality control policy to establish and implement biological condition assessment methods, scoring tools, and targets aimed at protecting the biological integrity in wadeable streams.
Existing Statutes and Regulations Related to Biostimulatory Substances
The existing statues and regulations are in various forms such as regional narrative or numeric nutrient objectives, an objective in the State Ocean Plan, water quality orders, and TMDLs which were adopted or are under development by various Regional Water Boards. Currently, there are approximately 32 TMDLs statewide which list nutrients as toxicants or eutrophication-related effects on beneficial uses.
All of the Regional Water Quality Control Plans and the Ocean Plan contain objectives for biostimulatory substances, nutrients and/or algal nuisance. These narrative or numeric objectives are generally consistent but have slight variations from region to region. A typical example from the San Francisco Water Board’s Basin Plan is:
“Waters shall not contain biostimulatory substances in concentrations that promote aquatic growths to the extent that such growths cause nuisance or adversely affect beneficial uses. Changes in chlorophyll a and associated phytoplankton communities follow complex dynamics that are sometimes associated with a discharge of biostimulatory substances. Irregular and extreme levels of chlorophyll a or phytoplankton blooms may indicate exceedance of this objective and require investigation (pg 3-3, section 3.3.3, 2010).”
The Ocean Plan states that, “Nutrient materials shall not cause objectionable aquatic growths or degrade indigenous biota.”
The State Water Board has issued precedential decisions as water quality orders. An example of this is Order WQ 2012-0013 for the Sacramento Regional Wastewater Treatment Plant to uphold an effluent limitation for nitrates as an interim effluent limitation necessary to reduce excessive cultural eutrophication and protect beneficial uses in the Delta and San Francisco Bay. The nitrate (as nitrogen) effluent limitation is set at 10.0 mg/L and will provide an initial step towards compliance with the narrative objectives for biostimulatory substances.
Information on Regional Nutrient Related Efforts:
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