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the Boulder Creek and St. Vrain Watershed |
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the Boulder Creek and St. Vrain Watershed |
The following table summarizes the Water Quality standards that are applicable to various sections of Boulder Creek and its tributaries. This table was developed in 2000 and may not reflect current standards.
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Constituent |
U.S. EPA Drinking Water MCL |
Colorado DPHE- Domestic water supply |
Colorado DPHE- Recreation Class 1 - Primary Contact |
Colorado DPHE- Recreation Class 2 - Secondary Contact |
Colorado DPHE- Aquatic Life Class 1 - Cold Water Biota |
Colorado DPHE- Aquatic Life Class 1 - Warm Water Biota |
Colorado DPHE- Aquatic Life Class 2 |
Colorado DPHE- Agriculture |
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water temperature (degrees Celsius) |
-- |
-- |
-- |
-- |
Max 20 (A) |
Max 30 (A) |
-- |
-- |
|
dissolved oxygen (mg/L) (B) |
-- |
3.0 |
3.0 |
3.0 |
6.0 (7.0 spawning) |
5.0 |
-- |
3.0 |
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specific conductance (micromhos/cm) |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
|
pH (standard units) |
6.5 - 8.5 (C) |
5.0 - 9.0 |
6.5 - 9.0 |
-- |
6.5 - 9.0 |
6.5 - 9.0 |
-- |
-- |
|
total alkalinity (mg/L as CaCO3) |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
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total hardness (mg/L as CaCO3) |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
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nitrate + nitrite (mg/L as N) |
10 |
10 (1-day) (D) |
-- |
-- |
-- |
-- |
-- |
100 |
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nitrate (mg/L as N) |
10 |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
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nitrite (mg/L as N) |
1 |
10 (1-day) (D) |
-- |
-- |
-- |
10 (1-day) |
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total phosphate (mg/L as P) |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
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ortho-phosphate (mg/L as P) |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
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total organic carbon (mg/L) |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
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fecal coliform (coliforms/100 mL) (F) |
-- |
2000 |
200 |
2000 |
-- |
-- |
-- |
-- |
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total coliform (coliforms/100 mL) |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
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total suspended solids (mg/L) (H) |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
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turbidity (NTU) (I) |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
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ammonia (mg/L) (un-ionized unless noted) |
-- |
0.5 (30-day) |
-- |
-- |
chronic: 0.02 |
chronic: 0.06 |
-- |
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chloride (mg/L) |
250 (C) |
250 (30-day) |
-- |
-- |
-- |
-- |
-- |
-- |
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fluoride (mg/L) |
4 |
2 (1-day) |
-- |
-- |
-- |
-- |
-- |
-- |
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sulfate (mg/L) |
500 |
250 (30-day) |
-- |
-- |
-- |
-- |
-- |
-- |
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total dissolved solids (mg/L) |
500 (C) |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
| Water Resource Uses | ||||||||
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MCL = Maximum Contaminant Level (The maximum permissible level of a contaminant in water which is delivered to any user of a public water system. MCLs are enforceable standards). |
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Domestic Water Supply = Surface water suitable or intended to become suitable for potable water supplies. After receiving standard treatment (defined as coagulation, flocculation, sedimentation, filtration, and disinfection with chlorine or its equivalent) these waters will meet Colorado drinking water regulations and any revisions, amendments, or supplements thereto. |
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Recreation Class 1 - Primary Contact = Waters suitable or intended to become suitable for recreational activities in or on the water when the ingestion of small quantities of water is likely to occur. Such waters include but are not limited to those used for swimming, rafting, kayaking, and water-skiing. |
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Recreation Class 2 - Secondary Contact = Suitable or intended to become suitable for recreational activities on or about the water which are not included in the primary contact subcategory. Such waters include but are not limited to fishing and other streamside or lakeside recreation. |
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Aquatic Life Class 1 - Cold Water Biota = Waters that are currently capable of sustaining a wide variety of cold water biota, including senstive species, or could sustain such biota but for correctable water quality conditions. Waters should be considered capable of sustaining such biota where physical habitat, water flows or levels, and water quality conditions result in no substantial impairment of the abundance and diversity of species. |
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Aquatic Life Class 1 - Warm Water Biota = Waters that are currently capable of sustaining a wide variety of warm water biota, including senstive species, or could sustain such biota but for correctable water quality conditions. Waters should be considered capable of sustaining such biota where physical habitat, water flows or levels, and water quality conditions result in no substantial impairment of the abundance and diversity of species. |
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Aquatic Life Class 2 - Waters that are not capable of sustaining a wide variety of cold or warm water biota, including sensitive species, due to physical habitat, water flows, or levels, or incorrectable water quality conditions that result in substantial impairment of the abundance and diversity of species. |
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Agricultural Waters that are suitable or intended to become suitable for irrigation of crops usually grown in Colorado and which are not hazardous as drinking water for livestock. |
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| NOTES | ||||||||
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(A) Temperature shall maintain a normal pattern of diurnal and seasonal fluctuations with no abrupt changes and shall have no increases in temperature of a magnitude, rate, and duration deemed deleterious to the resident marine life. Generally, a maximum 3 degrees C increase over a minimum of a 4-hr period, lasting 12 hrs maximum, is deemed acceptable. |
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(B) Standards for dissolved oxygen are 1-day minima, unless specified otherwise. The DO criteria is intended to apply to the epilimnion and metalimnion strata of lakes and reservoirs. DO in the hypolimnion may, due to natural conditions, be less than the table criteria. No reductions in DO levels due to controllable sources in allowed. |
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(C) secondary standard (non-enforceable guideline regulating contaminant that may cause cosmetic or aesthetic effects in drinking water). |
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(D) A combined total of nitrite + nitrate shall not exceed 10 mg/L, and nitrite shall not exceed 1 mg/L, at the point of intake. |
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(E) Established on a case-by-case basis; depends on whether salmonids (such as trout) and other sensitive fish species are present and on chloride concentration in the water. |
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(F) Colorado standards state that fecal coliform is an indicator only. It may indicate the presence of pathogenic organisms; however, fecal coliform counts from agriculture or urban runoff may not indicate organisms detrimental to human health. The bacteria standard is based on the geometric mean of representative stream samples. |
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(G) No more than 5.0% samples total coliform-positive in a month. (For water systems that collect fewer than 40 routine samples per month, no more than one sample can be total coliform-positive). Every sample that has total coliforms must be analyzed for fecal coliforms. There cannot be any fecal coliforms. |
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(H) Colorado standards state that suspended solid levels will be controlled by Effluent Limitation Regulations, Basic Standards, and Best Management Practices (BMPs). |
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(I) NTU = Nephelometric Turbidity Units |
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(J) The Surface Water Treatment Rule requires systems using surface water or ground water under the direct influence of surface water to (1) disinfect their water, and (2) filter their water to meet criteria for avoiding filtration so that at no time can turbidity go above 5 NTU; systems that filter must ensure that the turbidity go no higher than 1 NTU (0.5 NTU for conventional or direct filtration) in at least 95% of the daily samples in any month. |
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(K) Total ammonia concentrations should not exceed 0.5 mg/L constantly over a 30-day period at the point of intake. |
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(L) Acute levels depend on temperature and pH of the water body and whether cold water species are present. See CDPHE regulations for more information. |
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(M) For cold water, 0.02 mg/L; for warm water, 0.06 to 0.10 mg/L, depending on aquatic life present and on other water quality factors. |
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(N) Generally should be established at the respective levels for Class 1 segments, except where site-specific information submitted justifies an alternative acute standard. |
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For more information, see U.S. EPA regulations and Colorado DPHE regulations. |
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