Final California 2014 and 2016 Integrated Report (303(d) List/305(b) Report)

Supporting Information

Regional Board 1 - North Coast Region

Water Body Name:	Eureka Plain HU, Mad River Slough
Water Body ID:	CAR1100005219990617094843
Water Body Type:	River & Stream


DECISION ID	42261	Region 1
Eureka Plain HU, Mad River Slough

Pollutant:	Indicator Bacteria
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)(2012)
Revision Status	Original
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Fecal indicator bacteria (which includes fecal coliform) is being considered for placement on the Section 303(d) list under Section 3.2 of the Listing Policy. Under this section a single line of evidence (LOE) is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess fecal indicator bacteria in this water body. Fecal coliform data from the 2012 Integrated Report were assessed under both the shellfish harvesting (SHELL) and the water contact recreation (REC-1) objective, however the data are only counted one time in this decision. In accordance with Section 3.3 of the Listing Policy, a 4% exceedance rate shall be used to add waters to the List "if water quality monitoring was conducted April 1 through October 31 only". However, the data assessed in this decision include data collected during months outside the April - October range. Therefore, this pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy, using a 10% exceedance rate. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against adding this water segment-pollutant combination to the Section 303(d) list (i.e., sufficient justification to not list). This conclusion is based on the staff findings that: (1) The data used satisfy the data quality requirements of Section 6.1.4 of the Policy. (2) The data used satisfy the data quantity requirements of Section 6.1.5 of the Policy. (3) Fecal coliform samples do not exceed the objectives more than the allowable frequency listed in Table 3.2 of the Listing Policy. (4) Pursuant to Section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	This region was not assessed this cycle. All decisions have been carried over from the previous cycle and remain the same.

State Board 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 42261, Indicator Bacteria	Region 1
Eureka Plain HU, Mad River Slough

LOE ID:

33295

Pollutant:

Fecal Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

203

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

The samples were collected from two sites in Humboldt Bay. None of the 203 samples exceeded the evaluation guideline.

Data Reference:

Data for bacteria in Humboldt Bay, Jan. 2004-Aug. 2010

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The bacteriological quality of waters of the North Coast Region shall not be degraded beyond natural background levels. In no case shall coliform concentrations in waters of the North Coast Region exceed the following: In waters designated for contact recreation (REC-1), the median fecal coliform concentration based on a minimum of not less than 5 samples for any 30-day period shall not exceed 50 MPN/ 100 ml, nor shall more than 10% of total samples during any 30-day period exceed 400 MPN / 100 ml. Water Quality Control Plan, North Coast Region (NCRWQCB 2011)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Beach posting is recommended when single sample fecal coliform levels exceed 400 MPN / 100 ml. Draft Guidance for Fresh Water Beaches" (DHS 2011).

Guideline Reference:

Draft Guidance for Fresh Water Beaches. Last Update: May 8, 2006. Initial Draft: November 1997. California Department of Public Health.

Spatial Representation:

The samples were collected from two sites in Mad River Slough. Those sites were WQ # 27 and T2a.

Temporal Representation:

The samples were collected once a month from 2000 to 2010.

Environmental Conditions:

QAPP Information:

The samples were collected under the Management Plan For Commercial Shellfishing In Humboldt Bay, California. California Department of Public Health.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 42261, Indicator Bacteria	Region 1
Eureka Plain HU, Mad River Slough