36.11.423 WATERSHED MANAGEMENT - CUMULATIVE EFFECTS
(1) The department shall include an assessment of cumulative watershed effects on projects involving substantial vegetation removal or ground disturbance. Using the analysis, the department shall ensure that the project will not increase impacts beyond the physical limits imposed by the stream system for supporting its most restrictive beneficial use(s) , when considered with other existing and proposed state activities for which the scoping process has been initiated. The analysis shall identify opportunities, if any exist, for mitigating adverse effects on beneficial water uses.
(a) The department shall determine the necessary level of cumulative watershed effects analysis on a project level basis. The level of analysis shall depend on the:
(i) extent of the proposed activity;
(ii) level of past activities; and
(iii) beneficial uses at risk.
(b) The department shall complete a coarse filter screening on all projects involving substantial vegetation removal or ground disturbance. Except for small-scale projects with very low potential for impacts, additional analysis shall be required.
(c) The department shall complete a preliminary watershed analysis
on projects when coarse filter evaluations determine there is anything other
than low potential for cumulative impacts.
(d) The department shall complete a detailed watershed analysis when
coarse filter screening or preliminary analysis predict or indicate the
existence of unacceptable cumulative watershed effects as a result of the
(e) The department shall establish threshold
values for cumulative watershed effects on a watershed level basis.
(f) The department shall determine thresholds
for cumulative watershed effects by taking into account such items as:
(i) stream channel stability;
(ii) beneficial water uses; and
(iii) existing watershed conditions.
(iv) The department shall set threshold
values at a level that ensures compliance with water quality standards and
protection of beneficial water uses with a low to moderate degree of risk.
(g) The department shall set threshold values for cumulative effects
associated with projects proposed in the watershed of a water quality limited
water body at a level that provides for protection of beneficial water uses
with a low degree of risk.
(2) Whenever feasible,
the department shall cooperate with other landowners in watersheds with mixed
ownership to minimize cumulative watershed effects within acceptable levels of
History: 77-1-202, 77-1-209, 77-5-201, 77-5-204, MCA; IMP, 77-5-116, 77-5-204, 77-5-206, 77-5-207, MCA; NEW, 2003 MAR p. 397, Eff. 3/14/03.