5 Colo. Code Regs. § 1002-72.25
The provisions of 25-8-202(1) (c), and (2) and 25-8-205, C.R.S. provide the specific statutory authority for adoption of these regulatory amendments. The Commission also adopted, in compliance with 24-4-103(4) C.R.S., the following statement of basis and purpose.
BASIS AND PURPOSE
In September of 2000 the Commission adopted a new standard for the protection of Cherry Creek Reservoir. The new standard, a maximum growing season average of 15 ug/L of chlorophyll a, was determined to be protective of the uses of the reservoir. The Commission requested that the Division, in association with the Cherry Creek Basin Water Quality Authority (Authority) and other interested parties, draft an amended control regulation in accordance with the new standard.
The Commission expressed concerns about the deterioration of water quality in the Cherry Creek Reservoir. The Commission recognized the likelihood that additional point source and nonpoint source control efforts beyond those set forth in the proposed control regulation revisions will be necessary in the future. The authority was directed to proceed expeditiously in implementing the technology and information based controls required in the control regulation to meet the new water quality standards and protect the designated uses.
The Commission determined that it was appropriate to adopt the control regulation as a "phased TMDL" (Total Maximum Daily Load), or in the case of a reservoir, a "Total Maximum Annual Load" (TMAL). The "phased TMAL" process provides for the adoption of both point source and nonpoint source requirements that will provide protection for the reservoir, while additional studies of contributing problems to reservoir quality are investigated, and any additional necessary control programs are formulated. The Commission intends that this first phase of the TMAL will be in place within 3 to 6 years. An in-depth analysis of reservoir quality problems, the success or failure of existing control strategies, and new control requirements will be reviewed at future triennial hearings of the regulation.
Many changes to the numbering of the subsections of the regulation have occurred. This basis and purpose statement provides information about the major substantive changes to the regulation, rather than focusing on the details of numbering. The following provides an analysis of the basis and purpose for changes to each of the major sections of the control regulation.
The following changes or additions were made to terms relating to nonpoint and regulated stormwater sources. Several existing definitions were modified and several new definitions were included to correspond with terms used in the newly-added sections of the regulation dealing with nonpoint sources (Section 72.6) and regulated stormwater sources (Section 72.7). They are intended to clarify the distinction in the amended regulation between these categories of sources. Although nonpoint and regulated stormwater sources share an annual load allocation, they are subject to different control requirements under the regulation.
Accordingly, the definition of "nonpoint source," was made more restrictive, for purposes of this regulation, to include only activities or facilities that are not subject to the requirements of the stormwater regulations in Regulation 61 (5 CCR 1002-61). A definition for "regulated stormwater" was included to explain the distinction in this regulation between stormwater discharges from entities that are regulated under Regulation 61, and stormwater from other sources. Along these lines, the definition for "point source" was amended to expressly include conveyances of regulated stormwater. The definition for "stormwater" was added to clarify that the term, when not accompanied by the word "regulated," encompasses all sources of stormwater (regulated sources, as well as other sources).
A definition for "Municipal Separate Storm Sewer System" taken from Regulation 61 was included to clarify the term as used in Section 72.7 . The newly-added definitions for "disturbed areas," "individual home construction," and "land disturbance" were taken directly from the "Cherry Creek Reservoir Watershed Stormwater Quality Model Ordinance" (February 16, 2000), and they relate specifically to requirements for MS4s in Section 72.7 of this regulation. The term "best management practices" was expanded to clarify its applicability to nonpoint and regulated stormwater sources of pollution. A definition for "Water Quality Capture Volume" was added to explain the term as used in Section 72.7 concerning permanent BMP requirements for all land disturbances. The WQCV concept is more comprehensively discussed in the Urban Drainage and Flood Control District's Urban Storm Drainage Manual, Volume 3, which the Commission acknowledges as a nationally recognized reference on the subject. The Commission encourages use of this reference to those choosing to use the WQCV approach for determining the minimum requirements for areas of land disturbance.
The following changes or additions were made to terms of general applicability. A definition of "TMAL" was included to explain the term's use in Section 72.3 concerning the sum of total phosphorus allocations for the various sources. A definition for "Industrial Process Wastewater Sources" was added to clarify the scope of the term as used in Section 72.3 as a category for phosphorus load allocations. "Process Wastewater" was added to define the term as used in the definition of "Direct discharge". "Direct discharge" was modified to encompass a broader category of subsurface discharges, and to clarify that the term does not include discharges from regulated stormwater sources. The definition for "Wastewater Facilities" is identical to the definition for "domestic wastewater treatment works" in the Colorado Water Quality Control Act. The term was added to Section 72.3 as a phosphorus source category with corresponding load allocations that are further detailed in Section 72.4 . "Semi-urban Areas" was included to define the term as added to the list of wastewater facilities in Section 72.4 with corresponding wasteload allocations. A definition for "Land Application Return Flow Factor" was included to explain the term as used in the formula in Section 72.4 for calculating the monthly volume of phosphorus discharged by point source dischargers utilizing land treatment. "Phosphorus bank" was added to define the term as referred to in the Trading Program under Section 72.5 . "Cherry Creek Watershed" was expanded to more properly describe the nature of the area subject to this regulation and to elaborate on the meaning of tributaries, i.e., that they include wetlands and alluvial groundwater. "Background Sources" was modified to clarify that "groundwater "as used in the definition is limited to groundwater in its natural condition. Definitions for "Local Government" and "Division" were added for clarification. "Designated regional management agency" was changed to "Designated water quality management agency" to reflect the water quality-related functions of such entities.
Review of the Total Maximum Annual Load (TMAL) has revealed that the current allocations are not attaining water quality standards or protecting current designated uses. The Commission recognizes that this situation requires that the necessary controls be identified that will attain the applicable standards and protect the uses. The identification of the necessary controls will require considerable more investigation and evaluation before the Control Regulation can be revised to reflect these changes. During this period, the process for attaining water quality standards must continue by pursuing known technologies and processes throughout the Cherry Creek watershed.
The total maximum annual load (TMAL) of phosphorus for the reservoir was maintained at 14,270 pounds. The allocations of pounds to Nonpoint point sources, Background sources, Wastewater facility sources, Industrial process wastewater sources, and Individual sewage disposal systems also remain unchanged. The Commission recognizes that until additional investigations are completed, a new TMAL cannot be calculated. The Commission also recognizes that the reservoir is not attaining the chlorophyll a standard, and that a "phased TMAL" was the appropriate way to proceed at this time. The Environmental Protection Agency agreed with this approach. The Commission intends that the phased approach be implemented consistently with EPA Guidance (Guidance for Water-Quality Based Decisions: The TMAL Process, U.S. EPA, 1991. EPA 440-4-91 -001). Section 72.3 was modified by the addition of a Margin of Safety factor to the TMAL formula. Section 72.3 was also modified to reflect changes in the trading program. In the past trades were allowed which could lead to an exceedance of the point source allocation. This section makes it clear that any phosphorus awarded to wastewater facilities from the trading program will not exceed the TMAL allocation of 2,360 pounds. This change is reasonable since there is adequate phosphorus available in the wastewater facility allocation.
A new Section 72.3 was added to identify the future activities to be implemented by the Authority. These activities include additional point source controls, construction of nonpoint source projects, and investigative studies to better define the hydrology, phosphorus sources, chemical processes, and relative loads to the watershed and reservoir. The intent of the schedule is to identify appropriate activities implemented during the first phase of the TMAL that will result in reasonable progress in attaining water quality standards and to support future revisions to the control regulation if necessary.
In determining appropriate wasteload allocations (WLA) and effluent limitations for total phosphorus, the Commission sought to strike a balance between near term (2010) facility capacity needs, population and employment projections in the Metro Vision Plan, reasonably available treatment technology, and the fact that the recently adopted chlorophyll a standard is not being met in the reservoir.
The population projections in the Denver Regional Council of Government's (DRCOG) Metro Vision Plan used to project necessary wasteload allocations for the period during the Phase 1 TMAL proved to be problematic. The figures from the Metro Vision Plan were not consistent with many of the wastewater facility's recently approved site applications and/or utility plans. The Commission expects the Division and DRCOG to work together to establish accurate population and employment projections in the next Metro Vision Plan. This will ensure that accurate population and employment projections are used in planning efforts that support new or expanded wastewater facilities. The Commission has established wasteload allocations in the control regulation based on maximum allowable effluent concentration of 0.05 mg/l and the hydraulic capacities listed below, which are based on the near term (2007-2010) population and employment levels in the Metro Vision Plan. Where a site application for a hydraulic capacity in excess of the those listed below is approved, the applicant shall either accept an effluent phosphorus concentration limitation based on their current wasteload allocation, or obtain an additional wasteload allocations in accordance with the provisions of 72.4(6) or 72.5(2)(a), or 72.5(3) of the control regulation.
Arapahoe Co. W&WW Auth. | 2.40 MGD |
Parker Water & San. Dist. | 3.50 MGD |
Inverness Water & San. Dist. | 0.90 MGD |
Denver SE Suburban Water & San. Dist. | 2.00 MGD |
Meridian Metropolitan District | 0.74 MGD |
Stonegate Center Metropolitan District | 1.06 MGD |
The Commission set the wasteload allocations for wastewater treatment facilities at levels that were based on the design capacity that is expected to serve the respective service area until the 2007 to 2010 planning horizon. This is intended to provide dischargers with some certainty for additional growth during the period that the final TMAL is being developed. These figures were generally supported by recently approved site applications or utility plans. However, in some instances where recent planning was lacking or projected population and employment numbers significantly exceeded DRCOG projections, as in the case of Arapahoe County Water and Wastewater Authority and Cottonwood Water and Sanitation District, the flow used to calculate the respective wasteload allocation was reduced to a level that will accommodate the year 2007 to 2010 growth based on information obtained from the affected entities. Arapahoe/Cottonwood presented an alternate proposal for a combined allocation of not less than 83% (471 lbs.) of the original allocation (567 lbs.). Based on additional discussions between the Division and Arapahoe/Cottonwood, the Commission reallocated 37 pounds from the Reserve Pool to increase the Arapahoe/Cottonwood total combined wasteload allocation from 365 to 402 pounds.
An allocation was also set aside for future growth within the Semi-urban Areas based on predictions by DRCOG. This allocation can be accessed by new wastewater facilities or existing facilities that are serving development that would otherwise be served by a new wastewater facility outside of their urban growth boundary. Any increase in a wasteload allocation for existing facilities, other than through acceptance of out-of-service-area wastewater flows, can occur only as a result of a trade of nonpoint phosphorus for point source phosphorus in accordance with the revised trading requirements.
The table in Section 72.4 was modified to include the Semi-urban Areas wasteload allocation of 236 pounds of phosphorus. The wasteload allocation for Industrial Process Wastewater Facilities is now recognized in the table with its 50 pounds of phosphorus. This new category recognizes activities such as mining, industrial processes, and confined animal feeding operations. Specific wasteload allocations for facilities falling into this category may become necessary by the next triennial review. This additional category increases the wasteload allocation for all wastewater facilities to 1,928 pounds of phosphorus.
The Reserve Pool and Phosphorus Bank (formerly Trading Pool) phosphorus pounds were modified based on alternate proposals by the Division and the Authority to changes to Section 72.5 . The Division proposed that the Reserve Pool be a consolidation of the pounds of phosphorus previously allocated to the Emergency Pool, the Reserve Pool, and the additional pounds gained from the loading reduction as a result of lowering effluent limitations for phosphorus in point source discharges (432 lbs.). The Division proposed that the Phosphorus Bank is initially contain 0 pounds of phosphorus for immediate trading. The pounds of phosphorus gained from the construction of future nonpoint source projects or the stormwater permit requirements that exceed the minimum phosphorus removal requirement of 50% would be available for trading. The Authority proposed a reversal of the phosphorus pound allocations, with the Reserve Pool containing 0 lbs. and the Phosphorus Bank containing 432 lbs. Discussion of the both proposals by the Commission resulted in a reallocation of 216 lbs. to both the Reserve Pool and Phosphorus Bank. The addition of the Reserve Pool The total annual wasteload allocation now increases the total annual wasteload allocation to for wastewater facilities, industrial process wastewater sources, and developing areas, including the Reserve Pool and Phosphorus Bank, is now 2,360 pounds of phosphorus.
The Commission established a maximum 30-day average effluent limit for total phosphorus for direct discharges at 0.05 mg/l, and this level is significantly less than the previous limit of 0.2 mg/l. This reduction is necessary to make progress towards attainment of the chlorophyll a standard and the technology required to meet the lower concentration is within the economic means of the dischargers. Several types of technology that can meet the limit are well established in Colorado. Facilities that are not capable of meeting the applicable effluent limit immediately will be given a reasonable period of time, not to exceed the allowable date of July 1, 2004, to construct the necessary improvements under a schedule of compliance in their discharge permit.
Section 72.4 has been revised by identifying the area of Additional Prohibitions and Precautionary Measures as a component of future point source phosphorus controls. The revisions identify that the Commission may consider the adoption of future prohibitions or precautionary measures if controls on point sources are not effective in reducing phosphorus loads and attaining water quality standards. Several potential phosphorus point sources in the watershed are identified for possible consideration of additional control in the future. The Commission determined that the identification of these point sources would assist in complying with the TMAL and attaining water quality standards.
This section of the regulation provides three different mechanisms for adjusting wasteload allocations to point source discharges. Changes to these three subsections are summarized below.
Section 72.5 (Temporary Transfer of Phosphorus Allocations) was modified with one minor change. A new subsection (d) was added to provide a mechanism for review of any temporary transfers at the triennial review hearing to determine if permanent changes of the wasteload allocations are necessary.
Section 72.4 (Emergency Pool) in the previous regulation was eliminated from the regulation. Since the reservoir is not attaining water quality standards, the Commission determined that an Emergency Pool of phosphorus designed to accommodate exceedances of the point source wasteload allocations of phosphorus was not appropriate. The pounds in the Emergency Pool were added to the Reserve Pool.
Section 72.5 (Reserve Pool) provides phosphorus pounds for either new or expanded discharges, or for trading program projects that meet the requirements of the regulation. Point sources are limited to trading from within the Reserve Pool as an additional conservative action under the Phase 1 TMAL approach.
The allocation of total phosphorus to wastewater facilities is limited to 2,360 pounds per year and any increase in wasteload allocation will result in a corresponding decrease in the amount of phosphorus in the Reserve Pool. In the event that the Reserve Pool is fully depleted, increases in a wasteload allocation, outside of a temporary transfer of an allocation from another wastewater facility, can only occur as a result of a hearing by the Commission. The Commission found that the use of the Reserve Pool in this manner is necessary in order to reduce the amount of phosphorus reaching the reservoir.
The Reserve Pool is also the mechanism for providing phosphorus for trades of nonpoint source phosphorus that may be either directly traded and reflected in the appropriate discharge permit, or placed in the Phosphorus Bank as referred to in Section 72.5(3).
Section 72.5 (Trading Program) was modified in several significant ways. The program was restricted in several ways in recognition of the fact that the reservoir is not attaining the chlorophyll a standard or the phosphorous target adopted by the Commission in September, 2000. Recent trends indicate deteriorating water quality in the reservoir from the standpoint of phosphorus concentrations, general algal populations and increases in the relative abundance of undesirable blue-green algae.
First, the trading program was modified to preclude the trading of phosphorus from past or future nonpoint source projects funded by the Authority to 216 pounds (which are available for sale by the Authority), and to preclude trading from future nonpoint source projects funded by the Authority and from municipal water supply operations that may incidentally reduce phosphorus loading. Water supply activities that are specifically modified or designed to remove phosphorus in addition to beyond the incidental reductions from regular normal operations may be used in the trading program. Only the additional phosphorus pounds removed beyond the incidental reductions may be used in the trading program. The Commission determined that this provision would allow the trading program to create the incentive for more innovative water supply operations that are operated to remove additional phosphorus.
Second, the pounds of phosphorous in the Reserve Pool (formerly in the Trading Pool and Emergency Pool) that were generated through nonpoint source projects constructed by the Authority were removed. The Commission recognized that the benefits of those projects have already been realized by the reservoir, while water quality has continued to degrade. Utilization of those credits by point source discharges would have the effect of exacerbating the present exceedances of standards. The Commission also determined that because the Authority is financed through property taxes and user fees, it should pursue the construction of phosphorus removal projects that are intended solely for the improvement of water quality in the reservoir.
Third, the program was modified to allow trades for only three types of nonpoint source projects. One type of project was designed to provide retrofit enhancements for existing BMPs constructed prior to July 1, 2001, to achieve a higher level of phosphorus removal. A second type will provide BMPs for areas that were developed without providing for these water quality protective features. The third type of trade is aimed at achieving exemplary levels of phosphorus control and reduction in newly developing areas. By virtue of other provisions in this amended control regulation (see Section 72.7), new development is required to provide high level BMPs in line with the requirements of the specific criteria for stormwater permitting included in this regulation. However, it may be possible to remove phosphorous loading beyond these minimum requirements. In order to encourage such approaches in new and proposed developments, the Commission has authorized trades and banking of phosphorus credits subject to the criteria set forth in 72.5(3) for projects that can demonstrate reductions in phosphorus loading greater than a 50% removal efficiency. Phosphorus trading can occur on the increment of phosphorus removed above the 50% threshold. An applicable trading ratio and adjustment factors would apply only to the amount of phosphorus loading removed above the 50% threshold. The Commission determined that providing trading for other types of situations was unwarranted at this time due to the non-attainment of water quality standards.
Fourth, the trading program in 72.5(3)(g) also provides for a minimum trading ratio of two pounds of nonpoint source phosphorus for one pound of point source phosphorus. All trades will be subject to this minimum trading ratio. The 2:1 ratio is intended to assure that trading assists in making rapid progress toward attainment of the chlorophyll-a standard. This subsection requires that prior to determining the final trading ratio, adjustments must be made to assure that the phosphorus reductions generated from a nonpoint source project that are to be traded for additional loadings from a point source must be comparable in terms of the soluble or particulate form of the phosphorus. Point source discharges are generally high in soluble phosphorus and nonpoint source project-related load reductions to be utilized for a trade to a point source must provide a comparable level of soluble phosphorus removal before the trading ratio would be applied. The Commission was persuaded that soluble phosphorus poses a significantly greater risk to the trophic status of the reservoir than does particulate phosphorus, in part due to the large surplus of soluble phosphorus currently in the watershed. Soluble phosphorus is a more readily available nutrient for algae in the reservoir than is particulate phosphorus.
Additionally, this subsection requires that the fate and transport characteristics of the phosphorus traded from a nonpoint source project are similar or pose a greater risk of impact upon the reservoir than the phosphorus loading to be discharged from the point source receiving the credit. One potential example of the application of the adjustment factors follows:
Total Phosphorus removed by a nonpoint source project=100 lbs.
Of the 100 lbs. P'tot, 30% is soluble. The phosphorus discharged from the point source is virtually all in the soluble form. The amount of tradable phosphorus prior to the application of the trading ratio is 30 lbs. The point source discharge and the nonpoint source project site are similarly situated relative to the reservoir (i.e. similar fate and transport characteristics for the soluble phosphorus and no adjustment is needed). After application of the trading ratio the nonpoint source project could generate a 15 lb. credit for the point source.
Generally, when the point source discharge and the nonpoint source project site are similarly situated relative to the reservoir, or the nonpoint source project site is closer to the reservoir than the point source discharge receiving a credit, the conservative assumption is that the fate and transport characteristics for the comparable phosphorus load is similar and that no adjustment is needed. Adjustments based on the fate and transport characteristics of the phosphorus to be traded require the application of scientific professional judgement when the point source discharge is further away from the reservoir than the nonpoint source project location that is generating phosphorus credits. Adjustments must also consider the differences in time of travel and loading rates between surface water sources and groundwater sources of phosphorus. After the adjustment for the form of the phosphorus is made, the phosphorus trading ratio may be adjusted up to 3:1 if the nonpoint source project site is significantly further away from the reservoir than the point source discharge. Similarly, the trading ratio may be adjusted up to 3:1 if the time of travel to the reservoir of the phosphorus removed by the nonpoint source project is significantly longer than the time of travel of the phosphorus discharged by the point source.
Section 72.5 has been expanded to require that prior to the Authority approving a trade, certain minimum criteria must be submitted. These criteria are used to determine that the regulatory and technical requirements of the proposal have been met, and then can be used in calculating the amount of trading credits.
The Trading Pool has been recast as Phosphorus Bank in Section 72.5 of the revised control regulation. The Phosphorus Bank would allow entities to store pounds of phosphorus or to credit pounds of phosphorus to other entities. The value, in terms of pounds of phosphorus, of a nonpoint source project constructed by an entity other than the Authority can not be finally determined until it is evaluated in the context of a specific trade. Only in that specific context can the adjustment factors upon the trading ratio be applied properly. When the Phosphorus Bank is utilized to store pounds of phosphorus credited to an entity, the entity retains the rights to utilize the pounds or trade them to another entity. The Commission urged a measure of caution upon those who would intend to bank phosphorous credits for a long period. If necessary to attain the chlorophyll-a standard, future revisions of this control regulation may result in a reallocation or reduction of phosphorous credits from the Phosphorous Bank, as well as from the allocations for point and nonpoint sources in the watershed.
The Commission expects that in cases where an entity has acquired phosphorus credits but no longer has a need for them, the entity will either retire the credits for the benefit of water quality in the reservoir or establish a price for the credits that bears a reasonable relationship to the cost it incurred in obtaining the credits and the value of such credits as reflected by other similar and contemporaneous trades.
Sections 72.5 require that nonpoint source trade credits be retained only if continued performance of phosphorus removal is demonstrated. Projects that are not functioning continually can be removed as an acceptable trading basis.
Section 72.6 previously identified the choice and implementation of nonpoint source BMPs by local governments. Section 72.6 has been revised by identifying the areas of Nonpoint Source Best Management Practices, Public Information and Education, Additional Prohibitions and Precautionary Measures, and Floodplain Preservation Areas And Conservation Easements as components of nonpoint source nutrient controls. The Commission determined that the adoption of these nonpoint source controls will assist in complying with the Total Maximum Annual Load and the attainment of water quality standards for Cherry Creek Reservoir.
The revisions emphasize that Best Management Practices (BMPs) are to be chosen and implemented by entities that are responsible for activities or facilities that cause or are expected to cause nonpoint source pollution. The Authority is to submit a list of nonpoint source projects for construction during the next 3 to 6 years to the Division as a means of demonstrating that reasonable progress is being made to reduce phosphorus loading in the watershed. The projects are identified in the Authority's Cherry Creek Watershed Plan 2000 Appendix M - Stormwater Quality Drainage Plan. The regulation also identifies that responsibility for long-term operation and maintenance of nonpoint source projects by the Authority lies with project owners, with oversight by the Authority. Agricultural and silvicultural BMPs were also recognized, but are restricted based on the prerequisites in the Colorado Water Quality Control Act. The Commission recognizes that individual sewage disposal systems are a contributing source of nutrients to the watershed. Local governments and the Division are to encourage existing individual sewage disposal systems and new development to connect to central wastewater facilities.
The revisions require that a public information and education program be developed and implemented by the Authority. The Commission recognized that public information and education is recognized as an effective means to address nonpoint source pollution impacts associated with rapidly urbanizing areas. This feature will coincide with the information and education features required in the stormwater permitting requirements section.
The revisions identify that the Commission may consider the adoption of future prohibitions or precautionary measures if voluntary controls on nonpoint sources are not effective in reducing phosphorus loads and attaining water quality standards. Several potential nutrient sources in the watershed are identified for possible consideration of additional control in the future.
The revisions identify that floodplain preservation areas and conservation easements be included as a nonpoint source control mechanism. The Commission recognizes that the protection of riparian areas along Cherry Creek and its tributaries will assist in preventing future nutrient loading to the reservoir, and provide greatly needed recreational and aesthetic value to the watershed. The Commission also recognizes the difficulty in quantifying the amount of phosphorus loading reduction from these actions. The results of these nonpoint source control actions should be included as part of the TMAL Margin of Safety factor to facilitate progress towards attaining water quality standards in the reservoir.
Non-Point Sources
The revised control regulation includes changes to the section on non-point sources. The original definition of non-point sources included all stormwater runoff. Since the time it was originally promulgated, some stormwater sources are now regulated as point sources. These include most manufacturing, construction sites, and discharges from municipal separate storm sewer systems (MS4s). The definitions have been changed to reflect this distinction, including a definition for regulated stormwater'. However, due to lack of data, it was not feasible to separate out the regulated stormwater portion of the waste load allocation that was initially allocated to all non-point sources. This allocation is now designated for the combination of non-point sources and regulated stormwater discharges in the watershed.
Phase II Stormwater Regulations
The stormwater provisions of the regulation are based on several sources. First, the Phase II stormwater regulation as part of Regulation 61 was recently adopted by the Commission. It lists six minimum control measures that the regulated MS4s must implement once they are required to apply for a permit. These requirements are cross-referenced in this control regulation, and include Public Education, Public Involvement and Participation, Illicit Discharge Detection and Elimination, Construction Site Stormwater Runoff Control, Post-Construction Stormwater Management in New Development and Redevelopment, and Pollution Prevention/Good Housekeeping for Municipal Operations. The municipalities with MS4s that drain into the basin will be required to have permit coverage for those discharges that will include developing programs to cover these six measures.
In addition to the basic measures, this control regulation incorporates more detailed requirements under the Public Education, Construction, and Post-Construction Minimum Measures. The provisions of Regulation 61 concerning the six minimum control measures still apply to permittees covered by this Control Regulation. This includes the standard for permit compliance that stormwater management programs reduce the discharge of pollutants to the maximum extent practicable (MEP).
The Public Education additions require a focus on significant sources of nutrients. The additional requirements for Construction and Post-Construction are based on recommended procedures outlined in the Authority's Cherry Creek Reservoir Watershed - Stormwater Quality Model Stormwater Ordinance, Revised Version April 19, 2001. In the control regulation, the procedures are mandatory rather than recommended.
The Model Ordinance contains extensive detail when describing the BMPs and other requirements. The control regulation includes the major elements, but not the extensive details. The Division will include many of these detailed requirements in the general permit.
The Model Ordinance was reviewed by the Division and compared to the control regulation stormwater requirements. With the exception of specific issues addressed below, it was determined that a MS4 stormwater permittee required to comply with Section 72.7 that adopts the Model Ordinance as an enforceable program will be in compliance with the requirement in Regulation 61 to develop construction (Section 61.8) and post construction ((Section 61.8) programs, as well as the Sections (72.7.2(b) and 72.7.2(c)). The Commission's acceptance of this version of the Model Ordinance is in no way intended to relieve MS4s that adopt the Model Ordinance from the additional requirements in Regulation 61 to implement and enforce their programs. To the extent required in Regulation 61 and this control regulation, this includes, but is not limited to, developing procedures and regulatory mechanisms for:
Specific requirements of the control regulation that still must be addressed outside of the requirements in the Model Ordinance include the following:
These modifications could occur when the Model Ordinance is adopted by the MS4, or at least by the permit deadline in the first term of the MS4's municipal stormwater permit, in order to comply with Regulation 61 and this control regulation.
In addition, the Division maintains the right to require additional measures from MS4 permittees if needed to comply with the requirements of Regulation 61, this control regulation, or other State requirements.
The regulation does not include a reference to any standard manuals for specifications on BMPs. However, it is expected that all BMPs used for permit compliance will adhere to established engineering standards, such as are used in the Urban Drainage and Flood Control District's Volume 3.
The Commission promulgated these stricter requirements due to the issue of phosphorus loading in the basin. The more detailed requirements are for BMPs that, in most cases, directly or indirectly impact the amount of phosphorus entering state waters.
The procedures under Construction and Post-Construction in the Model Ordinance were incorporated into the control regulation with some changes. The most significant ones are as follows:
*the organizational structure was changed to increase flexibility on the part of the MS4;
*the MS4 was given the option of allowing additional exclusions from the program requirements, although some additional exclusions may require Division approval;
*the list of required BMPs was included, but the MS4s were given the option of limiting the list;
*the MS4s were also given the option of including additional and/or alternative BMPs if they have been shown to have similar nutrient removal capacities;
*the section on Post-Construction requirements at industries was changed to clarify that the MS4 has the ability to designate commercial or industrial sectors with a high pollution potential as requiring compliance with Post-Construction measures; and
*for the requirements of the post-construction minimum measure, BMPS must be required prior to discharge to state waters in compliance with Regulation 61 to protect the water quality of all state waters, including those between the site of development/redevelopment and Cherry Creek Reservoir. However, the additional requirements for control of phosphorus in Cherry Creek Reservoir, which go beyond those in Regulation 61, may be addressed through regional facilities located after the stormwater has discharged into state waters, but prior to discharge into Cherry Creek Reservoir.
As in the development of the Post-Construction measure in Regulation 61, concerns have been raised regarding the word ensure' in this section under the control regulation. The standard for permit compliance for MS4 stormwater permits is that municipalities ensure maintenance and operation of BMPs to the maximum extent practicable (MEP). In determining if an MS4 has complied to the MEP, the Division may consider such factors as the adequacy of the MS4's post-construction program, its ability to require that the necessary actions be performed by the responsible parties, how the MS4 has carried out the post-construction program, and, if necessary, the MS4's ability to provide appropriate mechanisms to ensure such maintenance and operation. The specific issue has been raised dealing with the extent of the legal ability of certain public entities, such as special districts, to adopt or implement certain requirements of this regulation and Regulation 61 due to their lack of land use approval authority. The Commission does not believe it would be prudent to create an express exemption from all regulatory requirements for such entities. The Commission intends that the Division will make such determinations on a case-by-case basis under the "MEP" standard as part of the application review process, or when drafting the MS4 permit, taking into consideration the legal authority of the applicant in light of each relevant program requirement. If handled within the permit, liability for portions of the minimum control measures may be removed from some MS4s that do not have legal authority for implementation if another MS4 is covering those portions with a qualifying program.
It is expected that the MS4 will put into place procedures, ordinances or other regulatory mechanisms that will require, to the extent allowed by State and local law, that BMPs be appropriately designed and planned, and provide for enforceable operation and maintenance by the owner/operator. Factors such as the extent of the inspection/verification system, and the procedures in place and implemented for instances when BMPs are not operated and/or maintained, can be evaluated by the State to determine if the MS4's program meets the MEP standard. Facilities such as special districts that may operate regional stormwater facilities under Intergovernmental Agreements with their respective municipal or county governments are expected to include provisions in those agreements for county municipality assistance in abiding by any regulatory and permit requirements that may be beyond their own statutory authority.
Area of Stormwater Permit Coverage
Many of the MS4s affected by the control regulation have discharges both into and outside of the watershed (i.e., into other drainages). The more detailed requirements in the control regulation will only apply to the discharges into the watershed. MS4s have the option of applying them jurisdiction-wide, but this will not be a requirement.
Basin Authority's Permit Status
The question was raised as to whether or not the Authority itself would require permit coverage under the Phase II stormwater regulation. As per the federal regulation, the Authority does meet the definition of a municipality. The question then becomes, does the Authority have a storm sewer system, as defined in Regulation 61. The Division has determined that at this time, the Authority does not own or operate an MS4. However, if circumstances change, the Division reserves the right to require the Authority to apply for permit coverage.
The control regulation previously included a section for monitoring of phosphorus from both point sources and nonpoint sources in the Cherry Creek Basin (Section 72.7). The purpose of the monitoring program was to determine phosphorus loadings from point sources, and phosphorus removal efficiencies of nonpoint source controls.
Section 72.8 has now been revised to encompass monitoring of nutrients, rather than only phosphorus. In the past, the main emphasis of watershed studies related to nutrient transport has been on the development of monitoring programs that provide information on total annual transport of phosphorus at various points along the main stem of Cherry Creek, and monitoring of trophic-state variables for Cherry Creek Reservoir. This section also has been expanded to identify the roles of the Authority, the Division, and other agencies in developing monitoring plans. The Commission decided that the monitoring program should continue as expanded, and include an emphasis on nitrogen as well as phosphorus.
Section 72.8 now includes the development and implementation of special studies, in addition to routine monitoring. Monitoring by itself is insufficient as the sole basis for a long-term program whose objectives are to document the validity of mass transport and reservoir trophic state modeling, and to identify environmental mechanisms that have an effect on water quality. The Commission agreed that routine monitoring will be combined with special studies having one or more specific objectives involving information that cannot be obtained from routine monitoring.
This section previously required reporting on control of nonpoint sources and monitoring of phosphorus to the Commission under three separate sections. The revisions have combined all reporting requirements into Section 72.9. The revisions require an annual report with specific information on point and nonpoint source controls, wasteload allocations, trading program, and other activities related to complying with the TMAL and attaining water quality standards. The Division and Commission will use this information in assessing the progress of the Authority.
This section previously required an annual report to demonstrate progress towards control of nonpoint sources. The revisions require a report at each triennial review on the progress of point and nonpoint source controls and effects on the reservoir. Recommendations can be made to the Commission at this time, and the Commission can adjust the TMAL load allocations, the Trading Program, and other requirements to assure that progress is being maintained.
PARTIES TO THE RULEMAKING
5 CCR 1002-72.25