Section 36.14 - Streamflow Criteria(1) Streamflow criteria are established by the categories described at 310 CMR 36.14(1)(a) through (c), which describe the modeled 2000-2004 existing conditions at the subbasin scale across a gradient of alteration from least to most altered for five bioperiods: early summer (May-June), late summer (July through September), fall (October and November), winter (December through February) and spring (March and April). The streamflow criterion for each category is the upper limit of the ranges shown at 310 CMR 36.14(1)(a) through (c). Withdrawals that contribute to a subbasin changing to a more altered category do not meet streamflow criteria and will only be permitted if the permittee demonstrates that there is no feasible alternative available to meet demonstrated water needs, and the permittee undertakes mitigation commensurate with the impacts of the withdrawal to the greatest extent feasible. (a)Biological Category for each subbasin is based on the simulated 2000-2004 existing condition of aquatic habitat using fluvial fish community characteristics as the surrogate indicator variable. Each biological category represents the percent alteration within the range of these fluvial fish community characteristics as a function of the following subbasin parameters: 2. cumulative groundwater withdrawal as a portion of the unimpacted August median flow;3. stream channel slope; and4. percent wetland within the stream buffer area. Simulated Alteration of Fluvial Fish Community Characteristics.
Biological Category 1: | 0% to 5% |
Biological Category 2: | >5% to 15% |
Biological Category 3: | >15% to 35% |
Biological Category 4: | >35% to 65% |
Biological Category 5: | >65% |
(b)Groundwater Withdrawal Category for each subbasin is based on the ratio of the 2000-2004 groundwater withdrawal volume to the unimpacted median monthly flow for August and represents conditions during the late summer bioperiod (July through September). Each groundwater withdrawal category represents the range of this ratio that would result in the biological category of the same number under conditions of low (1%) impervious cover. Simulated Groundwater Withdrawal Ratio for the Late Summer Bioperiod.
Groundwater Withdrawal Category 1: | 0% to 3% |
Groundwater Withdrawal Category 2: | >3% to 10% |
Groundwater Withdrawal Category 3: | >10% to 25% |
Groundwater Withdrawal Category 4: | >25% to 55% |
Groundwater Withdrawal Category 5: | >55% |
(c)Seasonal Groundwater Withdrawal Categories for each subbasin are based on the ratio of the 2000-2004 groundwater withdrawal volume to the unimpacted median monthly flow for the four other bioperiods below. Seasonal Groundwater Withdrawal Ratios for Additional Bioperiods
| Fall (Oct-Nov) | Winter (Dec-Feb) | Spring (March-April) | Early Summer (May-June) |
Seasonal Category 1: | 0% to 3% | 0% to 3% | 0% to 3% | 0% to 3% |
Seasonal Category 2: | >3% to 5% | 0% to 3% | 0% to 3% | >3% to 5% |
Seasonal Category 3: | >5% to 15% | >3% to 10% | >3% to 10% | >5% to 15% |
Seasonal Category 4: | feasible mitigation and improvement/no numeric criteria |
Seasonal Category 5: | feasible mitigation and improvement/no numeric criteria |
(2) Streamflow criteria have not been established for groundwater-driven water sources (the southern portion of South Coastal, Cape Cod, Islands, and portions of Buzzards Bay).Adopted by Mass Register Issue 1273, eff. 11/7/2014.