5 Colo. Code Regs. § 1002-36.10
These stream classifications and water quality standards for State Waters of the Rio Grande River Basin including San Luis Creek and all tributaries and standing bodies of water in all or parts of Alamosa, Conejos, Costilla, Mineral, Rio Grande, and Saguache Counties implement requirements of the Colorado Water Quality Control Act C.R.S. 1973, 25-8-101et seq. (Cum. Supp. 1981). They also represent the implementation of the Commission's Regulations Establishing Basic Standards and an Antidegradation Standard and Establishing a System for Classifying State Waters, for Assigning Standards, and for Granting Temporary Modifications (the "Basic Regulations")
The Basic Regulations establish a system for the classification of State Waters according to the beneficial uses for which they are suitable or are to become suitable, and for assigning specific numerical water quality standards according to such classifications. Because these stream classifications and standards implement the Basic Regulations, the statement of basis and purpose (Section 3.1.16) of those regulations must be referred to for a complete understanding of the basis and purpose of the regulations adopted herein. Therefore, Section 3.1.16 of the Basic Regulations is incorporated by reference. The focus of this statement of basis and purpose is on the scientific and technological rationale for the specific classifications and standards in the Rio Grande River Basin.
Public participation was a significant factor in the development of these regulations. A lengthy record was built through public hearings held on April 14, and 15, 1981. A total of 9 entities requested and were granted party status by the Commission in accordance with C.R.S. 1973, 24-4-101et seq. (Cum. Supp. 1980). A supplementary public rulemaking hearing was held September 15, 1981, restricted to those issues raised by the changes in the Act contained in Senate Bill 10 (1981). Such issues included but were not limited to: "The economic reasonableness" evaluation required by 25-8-102(5), the effect on water rights as required by 25-8-104; and the new considerations for the adoption of water quality standards required by 25-8-204 C.R.S. 1973, as amended. The record established in these hearings forms the basis for the classifications and standards adopted.
Conversely, if the ambient quality (x[BAR] + s) for a certain parameter exceeded the "table value" for the protection of a use, and there is information that the use is not in place, the use classification was modified or temporary modification to the parameters were established. Ambient quality is generally defined as the quality attributable to natural conditions and/or uncontrollable non-point sources.
One exception to the procedure just described is for whole body contact recreation (class 1). If an active domestic waste discharge was located on the segment in question, class 1 recreation was not recommended regardless of the ambient quality, unless there was information to show that the segment was actually used for swimming. This policy was established by the WQCC in order to avoid penalizing a discharger for protecting a use which is not in place and to limit possible harm to aquatic life due to chlorine residuals.
These qualifiers have been used to more fully describe characteristics of certain stream segments.
In addition to the significant distinction between Recreation - Class 1 and Recreation - Class 2 as defined in Section 3.1.13 of the Basic Regulations, the difference between the two classifications in terms of water quality standards is the fecal coliform parameter.
Recreation - Class 1 generally has a standard of 200 fecal coliform per 100 ml; Recreation - Class 2 generally has a standard of 2000 fecal coliform per 100 ml.
In accordance with S.B.10 the Commission has decided to classify as "Recreation - Class 2" those stream segments where primary contact recreation does not exist and cannot be reasonably expected to exist in the future, regardless of water quality. The Commission has decided to classify as "Recreation - Class 1" only those stream segments where primary contact recreation actually exists, or could reasonably be expected to occur. The reasons for the application of Recreation Class 2 are as follows:
The Commission finds that Colorado is a water short state and that it is experiencing considerable growth which places additional burdens on already scarce water supplies. These considerations mitigate in favor of a conservative approach to protecting future water supplies. Where existing water quality is adequate to protect this use, and in the absence of dischargers to these segments or testimony in opposition to such classification, the water supply use has been assigned because it is reasonable to expect that it may exist in the future in such cases. For stream segments that flow through, or in the vicinity of, municipalities, this conclusion is further justified, since there is a reasonable probability that the use exists or will exist. Where the water supply classification has been opposed, the Commission has evaluated the evidence on a site specific basis, and in many cases the classification has been removed.
Numeric standards have been assigned for the full range of parameters to a number of segments where little or no data existed specific to the segment. In these cases, there was reason to believe that the classified uses were in place or could be reasonably expected, and that the ambient water quality was as good as or better than the numeric standards assigned.
The standard of a 3°C temperature increase above ambient water temperature as defined is generally valid based on the data regarding that temperature necessary to support an "Aquatic Life - Class 1" fishery. The standard takes into account daily and seasonal fluctuations; however, it is also recognized that the 3°C limitation as defined is only appropriate as a guideline and cannot be rigidly applied if the intention is to protect aquatic life. In winter, for example, warm water discharges may be beneficial to aquatic life. It is the intention of the Commission in adopting the standard to prevent radical temperature changes in short periods of time which are detrimental to aquatic life.
The Commission finds that the Closed Basin Project will be likely to have a beneficial effect on aquatic habitat and any resulting temperature fluctuation is not in violation of this regulation.
It is the decision of the Commission to adopt these standards as basic standards because the presence of the organic parameters is not generally suspected. Also, the values assigned for these standards are not detectable using routine methodology and there is some concern regarding the potential for monitoring requirements if the standards are placed on specific streams. This concern should be alleviated by Section 3.1.14 of the Basic Regulations but there is uncertainty regarding the interpretation of those numbers by other entities. Regardless of these concerns, because these constituents are highly toxic, there is a need for regulating their presence in State waters. Because the Commission has determined that they have uniform applicability here, their inclusion as basic standards for the region accomplishes this purpose.
Consistent with the Basic Regulations, the Commission has not assumed that the table values have presumptive validity of applicability. This accounts for the extensive data in the record on ambient water quality. However, the Commission has found that the table values are generally sufficient to protect the use classifications. Therefore, they have been applied in the situations outlined in the preceeding paragraph as well as in those cases where there is insufficient data in the record to justify the establishment of different standards. The documentary evidence forming the basis for the table values is included in the record.
Cases in which water quality standards reflect these instream values usually involve the metal parameters. On many stream segments elevated levels of metals are present due to natural or unknown causes, as well as mine seepage from inactive or abandoned mines. These sources are difficult to identify and impractical or impossible to control. The classified aquatic life uses may be impacted and/or may have adjusted to the condition. In either case, the water quality standards are deemed sufficient to protect the uses that are present.
Levels that were determined to be below the detectable limits of the sampling methodology employed were averaged in as zero rather than at the detectable limit. This moves the mean down but since zero is also used when calculating wasteload allocations, this method is not unfair to dischargers.
Metals present in water samples may be tied up in suspended solids when the water is present in the stream. In this form they are not "available" to fish and may not be detrimental to aquatic life. Because the data of record does not distinguish as to availability, some deviation from table values, as well as the use ofs x[BAR] + s, is further justified because it is unlikely that the total value in all samples analyzed is in available form.
A number of different statistical methodologies could have been used where ambient water quality data dictates the standards. All of them have both advantages and disadvantages. It is recognized that the x[BAR] + s methodology also has weaknesses, in that the standard may not reflect natural conditions in a stream 100 per cent of the time, even though the use of x[BAR] + s already allows for some seasonal variability. However the use of this methodology is nevertheless justified since it provides the most meaningful index of stream quality of all methodologies proposed for setting stream standards.
Finally, the fairness and consistency of the use of any methodology in setting standards must turn on the manner in which the standards are implemented and enforced. It is essential that there be consistency between standard setting and the manner in which attainment or non-attainment of the standards is established based on future stream monitoring data. In addition the Division must take this methodology into account in writing and enforcing discharge permits.
Section 3.1.15 of the Basic Regulations states that "dischargers will not be required to regularly monitor for any parameters that are not identified by the Division as being of concern". Generally, there is no requirement for monitoring unless a parameter is in the effluent guidelines for the relevant industry, or is deemed to be a problem as to a specific discharge.
Where hardness and alkalinity numbers differed, the Commission elected to use alkalinity as the controlling parameter, in order to be consistent with other river basins and because testimony from the Division staff indicated that in most cases alkalinity has a greater effect on toxic form of metals than does hardness.
On some Class 2 Warm Water Aquatic Life streams containing similar aquatic communities to those found in the plain streams of the South Platte & Arkansas Basins, .1 mg/l unionized ammonia was selected as being appropriate to protect those species.
These streams generally contain both lesser numbers and types of species than those inhabiting class 1 streams due to physical habitat characteristics, flow or irreversible water quality characteristics. The Commission felt that the incremental expense to meet a 0.06 mg/l unionized ammonia standard for present or potential discharges along these streams cannot be justified. Flow in these segments is often intermittent or highly impacted by diversions.
Specifically, the Commission has relaxed unionized ammonia standards to .1 mg/l or greater on such stream for the following reasons:
Not all warmwater streams are comparable in terms of flow habitat, and types and numbers of species of aquatic life. Therefore, some variations in an appropriate ammonia standard must be tolerated, with the objective of protecting existing aquatic life. The Commission found this approach preferable to totally removing the aquatic life classification from impacted or marginal aquatic life streams.
Given the threat that radioactivity from uranium may pose to human health, it is advisable to limit uranium concentrations in streams to the maximum extent practicable. The Commission has adopted a standard of 40 pCi/l or natural background where higher, for the following reasons:
The Commission acknowledges that total cyanide is to be used in State Discharge permits until a method is authorized by EPA for measuring free cyanide, even though free cyanide is the parameter of concern. While cyanide has received special treatment in cases discussed in the segment - by - segment section which follows, a free cyanide standard based on Table Values has been established for most segments.
The Commission holds that the classifications which it adopts and the standards it assigns to them are linked. Disapproval by EPA of the standards may require reexamination by the Commission of the appropriateness of its original classification.
The reason for the linkage is that the Commission recognizes that there is a wide variability in the types of aquatic life in Colorado streams which require different levels of protection. Therefore, the numbers were chosen in some cases on a site specific basis to protect the species existing in that segment. If any reclassification is deemed a downgrading, then it will be based upon the grounds that the original classification was in error.
The Commission finds that these use classifications and water quality standards are economically reasonable. The Commission solicited and considered evidence of the economic impacts of these regulations. This evaluation necessarily involved a case-by-case consideration of such impacts, and reference is made to the fiscal impact statement for this analysis. Generally, a judgement was made as to whether the benefits in terms of improving water quality justified the costs of increased treatment. In the absence of evidence on economic impacts for a specific segment, the Commission concluded that the regulations would impose no additional economic burdens and would therefore be reasonable.
The Rio Grande and Santa Maria Reservoirs were resegmented as 2(b) because of fluctuating water levels which precluded their use as a class 1 cold water habitat. On Segment 2(b) the water supply classification was removed as there is no water supply in place nor is it reasonably expected in the forseeable future as testified to by the Rio Grande Water Users Association. These changes were made in recognition of conditions caused by the exercise of agricultural water rights.
On the basis of testimony received from the Colorado Water Quality Control Division and the Rio Grande Water Conservancy District, the Commission concluded that the metals values proposed by the Division were appropriate. Not withstanding the impact of diversions on stream flows, the stream segment as a whole has suitable aquatic life habitat to support the class 1 designation.
Examination of the data supported the Division's approach of pooling the data from the three reporting stations to describe existing quality in this segment.
The Commission accepted the resegmentation stipulated to by all the parties to better describe differences in water quality and habitat.
Segment 5(a) was changed to recreation class 2 consistent with the reasoning expressed in the general provisions of this basis and purpose. In adopting the class 1, cold water, aquatic life classification it was found that the habitat is sufficient to support a variety of aquatic life. Water supply and agriculture were removed. The uses are not in place and not reasonably expected.
For segment 5(b) the benthic surveys support the class 1 aquatic life designation. Standards for copper and silver were changed from proposed values due to inclusion of Chevron data.
Controversy over metals standards in testimony concerning segment 6(b) was resolved with respect to cadmium and zinc after the Commission evaluated additional data presented to it by the Chevron Corporation during the hearing. The values were changed from those proposed by the Division.
There was controversy over the issue on segment 7 protecting the mainstem of the Rio Grande from degradation by this segment. The testimony went to whether a goal of aquatic life class 2 with a temporary modification of ambient conditions should be adopted. The Commission resolved against such a goal. Cleaning up the mine tailing debris and stream bed is not likely to occur within 20 years. The technology may be available, but no single party or government agency appeared to be likely to take on the task. Furthermore, improvement of not only the water quality but also the stream bed to achieve an aquatic life goal makes attainment of the goal uncertain. An agricultural use is in place and is apparently not impaired by metals in excess of table values.
Evidence was presented that there was a wastewater discharge to the segment. No evidence was presented on behalf of that discharger. The Commission concluded that it was unlikely that there would be an impact on this discharger from the standards established due to minimum daily flow of 10 CFS in the stream.
Aquatic class 1, warm water rather that aquatic life class 2, warm water or cold water was assigned in recognition of reduced flows for 1/4 mile downstream of the Excelsior Ditch. However, the stream in this segment is a perennial stream with Increases in flow expected in the future as a result of the anticipated Closed Basin discharge downstream of Alamosa. A seasonal qualifier was adopted to reflect that flows and water quality will vary with the irrigation season. However, no adverse impact upon Alamosa's wastewater discharge is anticipated because of the existing dilution to discharge ratio and the presence of an obviously excellent fishery through Alamosa.
This segment was classified cold water class 1, aquatic life, despite the fact that segment 12 was designated warm water class 1, aquatic life. This was because there is no impact of the Closed Basin discharge upon this segment 13 according to the testimony of Mr. Thomas of the Bureau of Reclamation. Furthermore, segment 13 contains canyons where cooling occurs. In classifying this segment, the Commission recognized that this segment feeds a prime fishery immediately downstream in New Mexico.
At issue for 15(a) was whether the aquatic life classification should be retained as proposed, deleted, or whether the segment should be classified for any uses at all. The Commission concluded that these streams are dry for long periods of time and therefore do not warrant an aquatic life classification. There was testimony that waters from this segment were used for agriculture. A potential discharger would be restricted to protect the agricultural use. Additionally recreation class 2 was retained as a public health consideration.
15(b) Was separated in order to give protection to the Monte Vista and Alamos National Wildlife Refuge.
An interrupted flow qualifier was added by the Commission at the request of the Rio Grande Water Conservancy District on the basis of the irregular draining of Terrace Reservoir.
An interrupted flow qualifier was added by the Commission at the request of the Rio Grande Water Conservancy District due to their testimony on the impact of filling Terrace Reservoir.
Aquatic life was removed by the Commission from the proposed classification due to the Division's rationale that the segment is dry for much of the year.
The Water Supply Classification was removed by the Commission since it is a use not in place, nor reasonably expected in the future. The action was based on a recommendation contained in the 208 Plan and the Division's rationale.
Due to testimony on the existence of sensitive warm water species in this segment .06 mg/l unionized ammonia was assigned to protect these species while not adversely effecting the Magnesia wastewater treatment facility.
For 31(b), testimony by Trout Unlimited indicated this segment contained the only native population on public land in Colorado of the Rio Grande Cut Throat Trout, which is deserving of the higher protection provided by a classification of high quality class 2, which the Commission assigned.
The Commission felt that evidence indicated that carp were present in the segment and they would be adequately protected by assigning an ammonia standard of .1 mg/l.
The Commission found that no aquatic life can survive in the segment due to elevated levels of heavy metals coming from the drainage from abandoned mines.
5 CCR 1002-36.10