Final California 2012 Integrated Report( 303(d) List/305(b) Report)

Supporting Information

Regional Board 2 - San Francisco Bay Region

Water Body Name:	Morses Gulch Creek
Water Body ID:	CAR2013001220080624164407
Water Body Type:	River & Stream


DECISION ID	23195	Region 2
Morses Gulch Creek

Pollutant:	Nitrate
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status	Original
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Region 2 data was not included in the 2012 Integrated Report so all decisions are carried over from the 2010 listing cycle.

Regional Board Decision Recommendation:	After review of the available data and information, Water Board staff concludes that there is insufficient information to demonstrate that this water body is not meeting applicable water quality standards to support the cold freshwater habitat beneficial use. Therefore, the water body-pollutant combination should not be placed on the section 303(d) list.

State Board Staff Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

Line of Evidence (LOE) for Decision ID 23195, Nitrate	Region 2
Morses Gulch Creek

LOE ID:

23466

Pollutant:

Nitrate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water quality assessment in Morses Gulch Creek was conducted by SWAMP in 2005-2006. Nitrate concentrations (NO3-N) were analyzed three times and ranged from 0.19 to 0.23mg/L. The measured nitrate levels did not exceed the guideline threshold indicative of conditions leading to excessive algal growth, however, no data on algae or macrophytes are available to ensure compliance with the water quality objective.

Data Reference:

Data collected by the Surface Water Ambient Monitoring Program, San Francisco Bay Regional Water Quality Control Board. Years 4 and 5 Assessment

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

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.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)

Evaluation Guideline:

Total nitrogen levels greater than 0.5 mg/L can result in large masses of nuisance algae unless other factors limit algae growth (Bowie et al. 1985; Biggs 2000). Since nitrate is one component of total nitrogen in water, nitrate levels should also be less than 0.5 mg/L.

Guideline Reference:

Eutrophication of streams and rivers: dissolved nutrient-chlorophyll relationships for benthic algae. J. N. Am. Benthol. Soc. 19:17-31

Rates, Constant, and Kinetics Formulations in Surface Water Quality Modeling, 2nd Edition. EPA/600/3-85/040. USEPA Environmental Research Laboratory, Athens, GA

Spatial Representation:

Nitrate was sampled at one monitoring location in the lower reach of Morses Gulch Creek in the close proximity to Bolinas Lagoon.

Temporal Representation:

Water samples were collected for nitrate analyses during spring (April 2005), summer dry season (June 2005) and winter wet season (February 2006).

Environmental Conditions:

Morses Gulch is a small intermittent creek draining to Bolinas Lagoon in West Marin County.

QAPP Information:

All samples were collected and analyzed using procedures comparable with the SWAMP Quality Assurance Management Plan (SWRCB, 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)